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University Free State
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Universiteit Vrystaat
PRODUCTION EVALUATION OF OPUNTIA ROBUSTA AND O.FICUS-
INDICA CULTIVARS IN THE CENTRAL FREE STATE
By
Clement Ratseie
Submitted in partial fulfilment of the requirement of the
degree ofM.Sc. (Agric.)
Faculty of Natural and Agricultural Sciences
Department of Animal, Wildlife and Grassland Sciences
(Grassland Science)
University of the Free State
Bloemfontein
Supervisor: Prof. H A Snyman
Co-supervisor: Dr. HJ Fouché
November 2003
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Or JR-VrYltaot
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2 2 JUN 2004 .
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Acknowledgements
I would like to sincerely acknowledge the following persons and institutions for their
support, advice and guidance:
Persons
• Prof. H A Snyman (Supervisor), for his competent guidance, support and for
providing advice on academic matters.
• Dr. HJ Fouché (Co-supervisor), for his practical guidance, constructive criticism and
readiness to provide a helping hand at all times.
• Mr M Fair, for the precise statistical analysis and academic matters.
• Ms M Knight, for the precise editing of the work.
• Mr P Avenant, for his practical assistance.
• Mrs Ramakatane, for her continuous help throughout the study.
• Mr.G Van Rensburg, for his readiness to provide technical assistance at all times.
• Ms L Nel, for her assistance and support.
• Mr A Rowles, for his readiness to help at all times.
• My wife, my family and friends, for their highly appreciated encouragement and
support during my studies.
Institutions
• The Government of Lesotho, for granting me study leave to complete my studies.
• CMBSL Project of the Ministry of Environment, Gender and Youth Affairs (Lesotho)
for financial support.
11
• The Department of Livestock Services of the Ministry of Agriculture (Lesotho), for
granting me this precious opportunity to finish another chapter in life.
• The Department of Animal, Wildlife and Grassland Sciences at the University of the
Free State, for the opportunity and facilities to undertake this study.
• The Agricultural Research Council, for making the data available.
111
Declaration
I declare that the thesis hereby submitted by me for the partial fulfilment of the
requirement of the degree M.Sc. (Agric.) (Grassland Science) at the University of the
Free State is my own independent work and has not previously been submitted by me at
another University/Faculty. I furthermore cede copyright of the thesis in favour of the
University of the Free State.
c..f!5 cd;(Q)L
IV
Table of contents
Page
Acknowledgements
Declaration iii
Table of contents iv
Chapter
1 Introduction 1
2 Literature review 4
2.1 Ethnobotany 4
2.2 Ecology and environmental 6
2.3 Soil requirements 7
2.4 Site selection 7
2.5 Management practices 11
2.6 Soil management 15
2.7 Irrigation 16
2.8 Harvesting 16
2.9 Storage 17
2.10 Uses 17
3 Study area and Experimental procedures 26
3.1 Location 26
3.2 Climate 26
3.3 Soil 31
3.4 Experimental procedures 32
3.5 Collection of plant material 34
3.6 Cultivars and treatments 35
3.7 Liming and fertilisation 36
3.8 Planting and spacing 36
3.9 Weeding 38
3.10 Data collection 38
4 Evaluation of cactus pear cladodes 46
v
4.1 Introduction 46
4.2 Results and discussions 46
5 Evaluation of cactus pear fruit 68
5.1 Introduction 68
5.2 Results and discussions 68
6 General discussion conclusions 86
Summary 89
Opsomming 91
References 93
Appendix 107
1
CHAPTER 1
Introduction
Developing countries of the world are facing huge challenges in providing enough
food for their ever-escalating populations of people and animals. In the arid and semi-
arid regions of Southern Africa, where annual rainfall ranges from 150 to 300 mm,
food scarcity is not uncommon (De Kock 1965). The stock industry suffers major
losses as a result of shortage of food during droughts in these areas. Harsh winters,
aggrevated by drought add further pressure to the ailing plants. There is therefore, an
important feed gap in this so-called bridging up season. According to Le Houérou et
al. (1983) this feed gap is related more to the quality than the quantity of feed
available. Fodder shrubs, such as cactus ear are adapted to filling this gap, as they are
usually green throughout the year. The planting of fodder shrubs such as Opuntia
species is a strategy to alleviate the effect of drought on animal production systems
and has great potential to improve productivity in these arid and semi-arid areas
(Brutsch 1979; De Kock 1967; Pimienta-Barrios 1993; RusseIl and Felker 1985;
Oelofse 2002). The main reason for this is that it has a Crassulacean acid metabolism
(CAM) pathway (Oelofse 2002), which makes it a few times more efficient in water-
use requiments than Ca-plants (RusseIl and Felker 1985). Rainfall is the most limiting
environmental factor in the drier areas (Snyman 1998). It is, therefore, important that
when water is available it must be taken up as rapidly and as efficiently as possible.
The cactus pear plant is outstanding due to its shallow and extensive root system (Hill
1995; Ramakatane 2003; Snyman 2003). The cactus pear plants can utilise the drier
areas to their full potential (De Kock 1965; Snyman 2003).
Rather than depending On government to provide drought-aid, at huge costs to
taxpayers, livestock farmers need to be better prepared to overcome drought
conditions. One way to lessen the devastating effect of drought is to establish
drought-tolerant fodder crops such as the cactus pear (Opuntia spp) in arid and semi-
arid areas (Brutsch 1997). The plant's attributes make it an ideal "drought insurance",
2
as it is adapted to withstand severe drought conditions and still produce fodder at low
costs (Potgieter 1993). Changing climatic conditions, including global warming,
dictate the growing need for developing arid-zone crops. Cactus plants show great
adaptability to infertile soils and tolerate temperatures of up to 50-55°C although
temperatures close to 40°C for two or three consecutive days damage the fruits at
maturity (Potgieter 1995). They can therefore provide diversification and sustainable
agricultural systems in dry and infertile lands, where common crops often fail
(Schirra 1996).
The search for appropriate plant species able to grow successfully and produce in arid
areas has long been a concern for farmers living in harsh environments. Cactus pear is
a good option because it fits most requirements of a drought tolerant crop and can
also fill gaps in the fodder flow planning during certain periods of the season.
However, with renewed interest in this plant, there is a growing demand for better
selection (Oelofse 2002). Cactus peat requires low inputs and is therefore, capable of
establishing a sustainable system that will increase the efficiency and economic
viability of small and medium sized farms of low-income farmers (Pimienta-Barrios
et al. 1993: Oelofse 2002). The value of spineless cactus pear in subsistence
agriculture has been well documented (Barbera 1995, Brutsch 1979, 1993,2000).
Cactus pear (Opuntia spp) is a drought-resistant food and feed crop. In many areas
cactus pear fruit is an important food source for satisfying the nutritional needs of the
local, mainly poorer populations, for about three to four months of the year. The
knowledge of its chemical composition, nutritional value and effects on human health
has lead to a recent increase in the consumption of cactus pear. For the smaller
farmers, cultivation of cactus pear can be profitable due to the low investment
needed. There is scope for increased production on commercial scale for local and
export markets of cactus pear fruit. Prices obtained for prickly pear fruit on the
national fresh produce markets of South Africa compare very favourably with those
of more common fruits, such as apple, peach and orange (Brutsch 1994). Cactus pear
fruits represent a very important food source in satisfying the nutritional needs of
3
populations in various countries, especially those in South America (such as Bolivia,
Brazil, Chile, Columbia) and Mexico (Schirra 1996). Cactus pear fruits may also be
used in a wide range of products made at home, in small enterprises or on an
industrial scale such as jams, gelatine, syrup, dry fruit, candies and juice concentrates.
Increasing knowledge of environmental influence on fruit productivity and quality
will also allow a more profitable product (Brutsch 1979: Le Houerou 1992; Mizrahi
and Nerd 1999; Pimienta-Barrios et a1.1993)
Cactus pear plants differ with respect to yield, quality and also in sensitivity to biotic
and abiotic factors, which may affect growth and productivity (Pimienta-Barrios
1990). According to Barbera et al. (1993), productivity of Opuntia ficus-indica is
extremely variable from country to country. Although the aboveground productivity
of 0. ficus-indica can be substantially high, partitioning of dry matter into fruits and
cladodes has not been reported on in South Africa (Garcia de Cortazar 1991).
Increasing knowledge of environmental influences on fruit productivity and quality of
this plant will allow more profitable production (Brutsch 1997; Le Houérou 1992;
Pimienta et al. 1993; Mizrahi and Nerd 1999; Pimienta-Barrios 1993; Oelofse 2002).
Although cactus pear species can survive in drought prone areas, different species and
cultivars are adapted to different habitats, have different production systems, different
nutritive values and need different management practices. For this reason it is
essential that the establishment and management of cactus pear plantations be adapted
to the prevailing conditions, to ensure that the maximum value is obtained from the
plant. The aim with this study was therefore, to evaluate the productivity of Opuntia
ficus-indica (Green-pad cactus) and Opuntia robusta (Blue-pad cactus) varieties. The
study explores the practical potential of the two species of cactus pear for the semi-
arid areas and determines if they are different in terms of fodder and fruit production.
The information generated by this study could be of great use to both commercial and
subsistence farming communities who are considering cactus pear production.
4
CHAPTER2
Literature review
2.1. Ethnobotany
2.1.1 The role of the cactus pear
The oldest record of the use of cactus pear for human nutrition is found in excavations of
the cactus-rich valleys of Tehuacan in the state of Puebla, Mexico. These date back to
6500 BC (Smith 1967). Cacti and their products played a great role in the economic,
social and religious life of the Nahuatls (Bravo 1978). In one of the few preserved
pictographic writings of the time, the Codex Mendoza, there is an eagle perched on an
Opuntia. This is also the coat of arms of modern-day Mexico. Numerous pre-Hispanic
place names, encompassing the world Nochtli, indicate the wide spread of cactus pears,
e.g. Nocheztlan, Nochtepec and Xoconochtli (Hoffmann 1983).
2.1.2 Genesis of the use of cactus pears
Since 1520, Mexican Opuntias were taken to Europe and then, from the Mediterranean,
spread further to Africa, Asia and still further to Australia (Hoffmann 1983). The use of
wild cactus pear communities dates back 25 000 years, to when man arrived in the
territory now known as Mexico. These first settlers were hunters and gatherers, who used
the cactus plant (fruits, nopalitos and mature cladodes) in their diet
2.1.3 The role of cactus pear in religion and traditional medicines
As in many other cultures, plants in ancient Mexico made their way into religion. Due to
the vast number of species and dense populations, cacti have played an important role
(Bravo 1978). The thorns for cactus species served for self-sacrifice at a temple dedicated
to the god Huitzinahuac. Shoots from cactus plants were fastened as amulets to windows
and doors to drive off evil spirits. Cactus plants, being hallucinogenic, are an important
5
feature in customary rites in the sacred places. The traditional medicine of the Seri was
water, mixed with juice from the cactus pear: this formed the basis of a drink against
diarrhoea. A tea made from the roots of Opuntia Bigelovi Engelm acts as a diuretic
(Meyer and McClaughlin 1981). In Mexico, pregnant women having difficulty in giving
birth are given a drink made from the peeled, ground joints of the cactus pear. The
application of the cut cladodes to burns and swellings is a widely accepted practice
(Hoffmann 1983).
2.1.4 Forage and fodder cactus pears
Griffiths (1905) reported that during the United States Civil War, freighters loaded with
cotton were pulled by oxen to the only safe port of export at the Southern tip of Texas
(Brownsville). The route passed through extensive stands of spiny Opuntias. The
teamsters scorched the cactus by burning, and chopped or slashed it with an axe, spade or
machete to feed to the oxen. Due to the high water content of cactus, the oxen only had to
drink water once a week in winter and two or three times a week in summer. In the early
twentieth century, pressurised backpack "white gasoline" pear burners were used in
Texas to singe the spines from prickly pear so that cattle would eat it (Pluenneke 1990).
Also "cactus pear" is the same as "prickly pear" but is preferred because prickly pear has
a negative connotation. Spineless cactus pear is reported to have been introduced for the
first time in South Africa more than 300 years ago and were used mostly as life fences
and to protect crops against wild animals (De Kock 1970).
2.2 Ecology and environmental requirements
2.2.1 Ecology
The majority of Opuntia specres have originated from the dry, interior plateaux of
Mexico and the Southwestern U.S.A. However, some are believed to be native to Canada
and others from Patagonia. These areas have the following climatic conditions in
common: relativly mild winters, a pronounced dry period usually coinciding with the
winter months, predominantly summer rains and a mean annual rainfall which ranges
6
from 180 mm to 650 mm (Brutsch 1979). Climatic factors that control the growth of 0.
ficus-indica are rainfall (either lack or excess), atmospheric humidity, winter temperature
and the natural drainage of the soil (Monjauze and Le Houérou 1965).
2.2.2 Climatic requirements
Cactus pears are known around the world as unusual looking plants coming from hot, dry
and hostile desert areas.
2.2.2.1 Rainfall
The absolute minimum requisite for rain-fed cultivation is 200 mm per year provided the
soil is sandy and deep. On silty and loamy soils the minimum requisite is 300 to 400 mm
mean annual precipitation. Drainage is an important ecological factor; cactus pear, like
most cacti, is very sensitive to lack of oxygen in the root zone and cannot therefore,
withstand prolonged water logging. Clay soils that may be temporarily saturated, poorly
drained or water logged are not suitable for cactus pear production (Pimienta-Barrios
1994).
2.2.2.2 Frost damage
According to Le Houérou (1971) Opuntia ficus-indica species and clones can be severely
damaged by frost while Opuntia robusta (Monterey and Chico) species and clones can be
slightly damaged by cold temperatures. Most cacti grow in arid and semi-arid zones with
high temperatures, and are among the most tolerant of all plant species to high
temperatures, tolerating 50 to 55°C. Although spineless cacti are reasonably resistant to
cold and can withstand temperatures as low as -10°C when in a hardened stage, it is
desirable to establish plantations when possible on the northern or northeastern slopes in
the Southern Hemisphere (De Kock 1980).
7
2.3 Soil requirements
Cactus pears show great adaptability to various soil conditions as they can grow in poor
infertile desert soil and tolerate a wide pH range. Cactus pears also do well on a variety of
soil types, but for optimum growth and production, it is better to plant them in good soils
unless they are being used entirely for reclamation (Nobel 1986).
2.4 Site selection and planting
2.4.1 Site selection
The site should be preferably flat, but slopes up to 3% can be handled with simple soil
and water conservation practices such as contour planting (Brutsch and Zimmermann
1993).
2.4.2 Planting
2.4.2.1 Pre-planting operations
Land clearing is very important for the good establishment of Opuntias. The soil should
be ploughed to a depth of 600 to 800 mm, to ensure good drainage, as well as water
storage and eradication of perennial weeds. Weeds compete strongly with cactus pear
during the early stages following planting. The soil should be cross-ripped with a chisel
plough to improve drainage. Together with pre-planting operations, there is pre-planting
fertilisation (Brutsch and Zimmermann 1993). Fertilisation will be discussed in detail
later in the study.
2.4.2.2 Selection of planting material
Only cladodes that are more than a year old are used for planting a successful
establishment. The pads need not be allowed to wilt for a few weeks before planting. As
soon as wounds resulting from severence dry off and are healed (calloused) cladodes can
be planted (Brutsch and Zimmermann 1993).
8
2.4.2.3 Propagation material
Planting material should be collected from robust, productive and healthy plants. The
pads can be collected at the end of the growing season and subjected to slight dehydration
to allow suberization of the joints. Collected pads must be of medium to large size. After
collection cladodes must be stored in shade for two weeks. Cladode portions can be used
when planting material is in short supply but the smaller the portion the longer time the
new shoot will require to reach full size. The smallest portion that can be planted should
have at least 2-3 areoles on each surface (Brutsch and Zimmermann 1993).
2.4.2.4 Land preparations
When cactus pears are to be planted m areas that are predominantly grassland, it is
desirable to till the soil with a plough or disc to eliminate competition between the
grasses and newly established spineless plants. Elimination of perennial weeds or shrubs
and tilling of the soil are very important to facilitate formation (Brutsch and
Zimmermann 1993).
2.4.2.5 Planting time
the best planting time is in spring, from September to October. At this stage the cladodes
are well developed and they are ready to sprout. The plants should be well established
before the first frost and will then be able to withstand the cold winter. Planting should be
done after risk of frost is over. Freezing temperatures damage cactus pear, a safe lower
limit temperature would be SOCfor most cultivars. Tender cladodes are generally highly
susceptible to frost damage and they can start emerging 2-3 weeks after planting (Inglese
1995).
2.4.2.6 Planting methods
Besides placing cladodes upright into the soil when planting, there are various other
methods of planting the cladodes.
9
2.4.2.6.1 Laying the cladodes flat on the ground
Laying the cladodes flat on the ground with a stone or a spadeful of soil. This method
requires less labour and is suitable where soil tillage is impossible. In this way the
cladodes will develop more slowly. New growth takes place from the rim of the cladodes
and the resultant stems are weakly jointed to the original cladodes, these stems are weak
and often break off easily (Inglese 1995).
2.4.2.6.2 Planting cladodes on their edge
Planting cladodes on their edges in loose soil or against the side of a furrow is another
method that can be decided on. In this case a single furrow-plough or a sub-soilercan be
used to make the furrow. The point where the pad was cut off should be kept above the
surface of the soil as this is where fungi, which cause rotting can enter the cladodes. This
method results in strong plants, which also develop rapidly. The plants utilise rainwater
collected in the furrows. This method, however, requires more labour than the first
method (Inglese 1995).
2.4.2.6.3 Planting double cladodes
The quickest growth and development is obtained when double cladodes are planted.
More cladodes, time and labour are required for this method (Inglese 1995).
2.4.3 Spacing
Between the rows the spacing could be 3.0 to 4.5 m and 1.5 to 2 m within the rows
(Ingles 1995).
10
2.4.4 Fertilisation
Fertilisation is necessary at planting if the soil is low in phosphate and potash. These
deficiencies can in most cases be supplemented with 50 to 100 kg super phosphate and 50
to 100 kg of potassium chloride per hectare. If the soil is poor in nitrogen, 50 kg of
ammonium sulphate per hectare can be applied. Fertilisation should be based on soil
analysis. Late summer application of N fertiliser to cactus pears could induce an
additional flush offloral buds in autumn (Nerd et al. 1993).
Chemical fertilisers can be applied during the rainy season. Providing half of the nitrogen
fertiliser early in the season and the rest 45 days later is advisable. The fertiliser must be
spread along the rows and slightly covered with soil (Nerd, Mesika and Mizrahi 1993).
Nitrogen fertilisers can be applied at the rate of 100 to 200 kg per hectare (Flores- Valdez
1992). To ensure high yields it is necessary to apply manure (broadcast or ploughed in)
prior to planting. For better results the manure can be supplemented with synthetic
fertilisers. Chemical fertilisers are a quick source of nutrients, while manure represents a
slow release supply (Flores- Valdez 1992).
2.5 Management practices
2.5.1 Pruning
The objectives of pruning change with the age of the plant. Pruning and training systems
include formative pruning, production pruning and renewal pruning (Inglese et al.
1994b).
2.5.1.1 Formative pruning
The first year after planting, new cladodes developing downwards, horizontally or from
the basal portion of the parent cladode must be removed. To develop a vase, no more than
two upright cladodes should be selected on the parent cladode. Recommendations for
11
formative pruning include the removal of damaged cladodes and fruits, which compete
with plant growth during its development (lnglese et al. 1994a).
2.5.1.2 Production pruning
One of the objectives of pruning fruiting plants of cactus pear is to expose as many
cladodes to the sunlight as possible. Cladodes that develop in the inner shaded portion of
the canopy are less productive than exposed outer cladodes (Inglese et al. 1994a). The
opacity and thickness of the cladodes make pruning essential to facilitate light penetration
into the canopy. Hidden cladodes, which develop in dense canopy, as well as cladodes
that touch the ground are easily parasitised by cochineal and are difficult to reach with
pesticide sprays. The reduction of canopy density by pruning makes cultural practices
such as fruit thinning, scozzolatura and harvesting easy to practice and help to improve
fruit quality. The closer the planting space, the higher the pruning intensity and
frequency. No more than two daughter cladodes should be retained on the cladode to
maximise development and reduce wind damage (lnglese et al 1994a). A summary of
mean clad ode yield, mean cladode mass and mean number of cladodes needed to be
pruned per plant of cactus pear are presented in Table 2.l.
Table 2.1 Mean cladode yield per plant, mean cladode mass and mean number of
cladodes that needed to be pruned per plant of cactus pear (Opuntia ficus-indica
(L.) Mill.] (Oelofse 2002).
Cultivar Cladode (kg Clad ode mass (kg) Number of cladodes
plant ol) pruned (plant ol)
Skinners Court 63.36 2.80 22.9
Nudosa 63.61 l.36 47.0
Gymno Carpo 63.02 1.16 56.6
Morado 78.84 1.18 72.5
Zastron 71.18 1.17 65.6
Malta 5l.95 1.10 53.0
Algerian 63.48 l.23 56.3
Turpin 107.01 l.05 107.6
Meyer 102.05 1.14 9l.9
Roedtan 77.09 l.09 72.0
12
2.5.1.3 Renewal pruning
Rejuvenation of debilitated plants can be achieved by heading back to 3 to 4 year-old
scaffolds (Mulas and D'hallewin 1990). Heavier pruning can be practised to stimulate
growth in weak plants, heading back to lignified cladodes. The plant resumes fruiting 2 to
3 years after pruning, depending on the pruning intensity. According to Mulas and
D'hallewin (1990), to improve the effect of pruning, the plants can be fertilised with urea
(60 kg ha-I) soon after pruning. Pruning principles and recommendations can be
summarised as follows:
• remove inner cladodes and those oriented downwards, horizontally or close to the
ground,
• avoid the development of a dense canopy, which increases the risk of cochineal
infestation, reduces light interception and hampers pest control, fruit thinning and
fruit harvest,
• leave no more than two daughter cladodes on a parent cladode, in order to maximise
cladode growth,
• remove cladodes developing from fertile parent cladodes,
• avoid pruning during rainy or cold periods,
• avoid summer planting, unless for summer growth and
• control plant height at 2 to 2.5 m (Inglese et al. 1994a).
2.5.1.4 Pruning time
Pruning should not be carried out during the rainy season m order to prevent the
development of cladode putrid rot and scabies (Inglese et al 1994a). In South Africa,
Wessels (1988) suggested pruning from May to July, after fruit harvest, when the plant is
no longer actively growing.
2.5.1.5 Fruit thinning
Thinning times must be from two weeks before bloom or two weeks after set. Cladodes
with more than ten fruits show irregular or delayed ripening, which decreases harvest
13
efficiency. Earlier thinning requires more time because of the small size of the flower
buds, whereas removing' fruits, three or four weeks after set would reduce the
effectiveness of thinning (Inglese et al. 1994a). Reasons why farmers should thin fruits
include improved fruit size, improved internal quality, easy picking process and to
prevent broken plants due to too much fruit set. When fruits are thinned at the right stage,
there are relatively less seeds in relation to pulp. Fewer seeds enhance the eating quality
of the fruits and improve consumer reaction. Research concerning the thinning of cactus
pear showed that optimum fruit size and quality are obtained when about 9 to 12 fruits
are left per cladode (Brutsch 1992). The fruit yield and mass obtained from different
cultivars with different plant width and height are presented in Table 2.2.
Table 2.2 Plant height, width, fruit yield and fruit mass (Oelofse 2002).
Cultivar Plant Plant Fruit yield Mean fruit
width (cm) height (cm) (t ha-t) mass (g)
Skinners Court 251.0 203.0 4.97 185.08
Nudosa 224.0 175.0 14.58 235.84
Gymno Carpo 217.0 175.0 30.67 170.81
Morado 223.0 207.0 19.60 145.68
Zastron 242.0. 223.0 17.96 136.68
Malta 222.0 175.0 23.22 169.75
Algerian 221.0 173.0 24.98 161.88
Turnip 223.0 186.0 28.67 181.19
Meyers 231.0 194.0 26.72 176.39
Roedtan 208.0 181.0 23.66 171.74
Average 226.2 189.2 21.50 173.50
LSD (P = 0.05) 25.836 10.8508 3.3766 24.6436
14
2.5.2 Scozzolatura ( Removal of the reproductive buds to delay fruit ripening)
Late fruit production of cactus pear is obtained by forcing the plant to produce a second
bloom. This involves taking away flowers and cladodes of the spring flush. In a second
bloom, bigger fruits, with a lower fruit-to-flesh ratio than summer ones ripen from the
beginning of October to the end of November in the Northern Hemisphere and from the
beginning of March to the end of April in the Southern Hemisphere. The spring flush
removal (S.F.R) takes place between the end of May and the last week.of June in the
Northern Hemisphere, and in October in the Southern Hemisphere, when the main bloom
occurs. Removal time affects reflowering rate, fruit development and ripening time
(Barbera et a1.1995, Brutsch and Scott 1991). The pre-bIoom removal results in the
highest re-flowering rate, while removing the spring flush after petal shedding reduces re-
flowering by up to 50 to 70%. Proper scheduling of S.R.F removal could extend the fruit
harvest period. This could be useful for overcoming harvest and market problems related
to the poor storage performance of the fruit. The number of cladodes produced after
scozzolatura is 10 to 40% lower than for the spring flush. In light soil with low water
content, irrigation should be applied at the moment of S.F.R to improve re-flowering
(Inglese et al. 1994a).
2.6 Weed control
Weed control is essential for sustainable production of cactus pear. Weeds compete with
the shallow root system of the cactus pear for nutrients, particularly during the early
stages of plant development. Young plantations can be lost completely if weed control is
not properly managed. Weed control is the main factor influencing Opuntia production
costs (During the initial growth stage, the growth of cactus can be severely retarded by
grass and other herbaceous vegetation). According to Santos and Albuquerque (2001),
horses can be admitted to the spineless cactus plantation, as they will eat most forage but
. not the cactus. After the cacti reach a height of more than 1 m, livestock can be admitted
at the rate of 1 cow per hectare. Once planted, Opuntia can serve as a nurse plant for
many weed species, so periodic weeding becomes an integral element in crop
15
management (Santos and Albuquerque 2001). Maintain the plot free of perennial weeds
and shrubs to eliminate competition with Opuntia. Soil cultivation should be restricted to
the minimum in order to avoid damaging the cactus pear's superficial root system. To
avoid any damage to the roots and to preserve soil structure, weeds can be mowed and
left as mulch on the soil to retain moisture and smother weed growth. In summer the soil
should be lightly worked with a superficial scraper or a rotating hoe, in order to reduce
water loss. Successful chemical weed control can be attained by use of Paraquat and
Glyphosate (Felker 2001). Glyphosate at 20 g r1 is not phytotoxic to Opuntia (Felker and
RusseIl 1988).
2.7 Irrigation
Irrigation is not normally practiced in South Africa (Van der Merwe et al. 1997). Basin
irrigation is not suitable as it enhances leaching of nutrients because of the high
permeability of the soil in which cactus pear grows. Localised micro-sprinklers, which
cover a fairly large soil surface area with small volumes, are suitable for the characteristic
cactus pear root system. Drip irrigation can also be profitably practised, but it results in
nutrient leaching and root rot ifnot properly managed (Nerd et al. 1991).
2.8 Harvesting
Cactus pear fruits can be manually picked with thick gloves and glasses to avoid injuries
from glochids. It is recommended to start picking early in the morning, when glochids are
wet and stick to the fruit. In South Africa fruits are handled with a picking glass and cut
with grape-scissors. The cut must include a thin layer of the cladode to prevent rapid loss
of fruit weight and preserve storage ability (Barbera et aI.1992a). The harvesting period
for different cultivars differs, the main harvesting period could be from January to March
at Fort Hare, (E. Cape) (Brutsch 1979). The main harvesting period of the fruits for some
cultivars as well as the fruit characteristics is presented in Table 2.3.
16
Table 2.3 Fruit characteristics of five promising cactus pear cultivars [Opuntia .ficus-
indica (L) Mill] (Brutsch 1979) at Fort Hare, E. Cape.
Cultivar Main Mean fruit External colour Internal colour
harvesting mass (g)
period in
E.Cape
Algerian End Jan. - end 88 Red Red
Mar.
Blue Motto Early Feb. - end 109 Light green Yellow/Khaki
Mar.
Gymno Carpo End Jan. - end 102 Yellow Yellow
Mar
Malta Early Feb. - end 85 Yellow Yellow
Mar.
Morado End Jan. - end 97 Light green White
Mar
Skinners Court Early Feb. - end 107 Light green Light
Mar. green/white
Cladodes for "nopalitos" in Mexico should be harvested 30 to 60 days after sprouting,
when they weigh between 80 to 180 g and are 150 to 200 mm long. Some producers
harvest by pulling and twisting the "nopalitos" off, however, this can produce injuries
and rotting. Most farmers use a knife to harvest cladodes. Nopalitos should not be cut at
the base as this causes rotting. Cutting at the joint between the supporting cladode and the
"nopalitos" helps to delay deterioration (CantweIl 1992; Corrales1992). Mature pads can
be collected at the end of the growing season. The number of cladodes to be harvested
varies with cultivar and age of the plant. During the first year, 2-4 cladodes per plant can
be collected. In order to obtain constant yield, the plants are left with only two branches
("rabbits") oriented along the broad-bed. It is more efficient to collect and store them
close to the livestock yard until needed (CantweIl (de Trojo) 1992; Corrales 1992).
2.9 Storage
Nopalitos should be stored at 5°C to 10°C to avoid yellowing and inward curving due to
loss of water. Proper storage reduces respiration rate and increases post-harvest shelf life
from less than one week at 20°C to three weeks at 5°C. Cactus stems lose their brilliant
17
shiny appearance and become dull green in colour with time following harvesting. Visual
quality can be maintained for about two weeks if storage takes place at 10°C and for three
weeks at 5° C. After one week at 20° C and two weeks at 15°C, the vestigial leaf senesce,
blacken and abseise (CantweIl 1992).
2.10 Uses
Cactus parts can be used in many different ways, with only the important ones discussed.
2.10.1 Cactus pear as fruit crop
Cactus pears have the wellknown glochids (Gibson and Nobel 1986), which are removed
before the fruit can be peeled. The major components of the fruit pulp are 85% water, 10-
15% carbohydrates and 0.25-0.03% of vitamin C (Gurrieri et al. 2000). Cactus pear fruits
can be used in a variety of ways such as:
• strained into deserts,
• used in beverages,
• used in syrup, jelly and candies,
• seeds are dried and used in soup or ground and used in sweet cakes and
• the fruit is peeled and eaten fresh. The common name of the fruit is "tuna" in Latin
America, Ficodindia (Indian fig) in Italy, Tzabbar in Israel and Sabar in Arab
countries (Brutsch and Zimmermann 1993).
In the developing nations, where cactus pear is consumed by only a small section of the
population, it can be considered a luxury item. But in Mexico and North Africa, it makes
substantial contribution to the diet of peasant populations during the summer months, and
also at other times, if processed. It is, therefore, an important commodity. In South Africa
the fruit is already known to a wide cross-section of the population. There is a good
market for the fruits in large centres such as Pretoria, Johannesburg and Bloemfontein
(Brutsch 1979). The fruit contains a large number of seeds. The seed is hard coated (De
Kock 1980). The negative aspects of the fruit can be listed as follows; the unpleasant
glochids on the fruit which have to be carefully removed before the fruit can be handled
18
and eaten, the thick outer cover (peel) which accounts for more waste (inedible fraction)
than in most other fruits, severe constipation resulting from eating large quantities of the
fruit at anyone time and the large number of seeds (Brutsch 1979). According to Oelofse
(2002), the ripening times of fruits of different cactus pear cultivars differ. Most fruits
ripening in January. The dates of the basic phenological stages of each cactus pear
cultivar in Limpopo province are summarised in Table 2.4.
Table 2.4 Dates ofthe basic phenological stages of cactus pear [Opuntiaficus-indica (L.)
Mill.] cultivars evaluated in the 1999/2,000 season at Limpopo province (Oelofse
2002).
Cultivars Reproductive Vegetative 50% Anthesis 50% Fruit
budbreak budbreak ripening
Skinners Court Week 2 in July Week 3 in August Week 3 in Week 2 in
October January
Nudosa Week 2 in August Week 2 in August Week 4 in Week 4 in
October January
Gyrnno Carpo Week 2 in August Week 2 in August Week 3 in Week 3 in
October January
Morado Week 2 in August Week 3 in August Week4 in Week 3 in
October January
Zastron Week 2 in July Week 4 in August Week 4 in Week 1 in
October January
Malta Week 1 in August Week 3 in August Week 3 in Week 2 in
October January
Algerian Week 1 in August Week 4 in August Week 3 in Week 2 in
October January
Turpin Week 2 in August Week 3 in August Week 3 in Week 2 in
October January
Meyers Week 3 in August Week 3 in August Week 4 in Week 3 in
October January
Roedtan Week 2 in August Week 2 in August Week 4 in Week 3 in
October January
Size, percentage flesh, colour, total soluble solids (TSS) and seed content are the main
parameters characterising fruit quality. Fruit size depends on seed number (Barbera et al.
1992c), cladode load (Barbera et al. 1993b), water availability, (Barbera 1984) and
ripening time (Barbera et al. 1992c). The most sought after fruits, on the international
markets are yellow-orange (peel and flesh colour). Sugar content plays a decisive role in
19
defining fruit quality, because consumers favour sweet fruits (Barbera et al. 1992b). Fruit
yield varies considerably with ecological conditions, the care given to the crop and the
nature of the clone and cultivar (Monjauze and Le Houérou 1965). The minimum criteria
for cactus pear varieties evaluated for fruit production are summarised in Table 2.5.
Table 2.5 Minimum criteria for cactus pear varieties evaluated for fruit production
(Potgieter and Mkhari 1989).
Characteristics Minimum criteria
Fruit yield potential
Year 2 1 t ha"
Year 3 2.5 t ha"
Year 4 4 t ha"
Year 5 7 t ha-l
Year 6 10 t ha"
Year 7 15tha-!
Year 8 20 t ha-!
Fruit mass >140.0 g
TSS >13uBrix
Pulp percentage >50%
Peel thickness <6mm
One of the major constraints limiting the consumption of cactus pears is the presence of
the thick, hard seed in the flesh (Pimienta 1990). Empty rudimentary seeds, caused by
early failure of embryo growth, are common in cactus pears and allow flesh development.
The ratio of empty to normal seed is one of the most important parameters that define
fruit quality (Pimienta and Engleman 1985). The fruit size depends on the number of
fecundate and aborted seeds. It has, however, not been established why the seeds abort
(Archibald 1935: Barbera et al. 1994).
20
2.10.2 Cactus pears as animal feed
Fresh cladodes provide dependable sources of food and drink for livestock and poultry.
Brutsch and Zimmermann (2000) pointed out that the cladodes, when supplemented with
cotton seed meal, offer all the water and nutrition for animal needs. If cladodes make up
more than 50% of animal's feed, they will, however develop diarrhoea. A wide variety of
animals such as sheep, pigs, horses, ostriches and circus elephants can be raised on cactus
cladodes. When fed to dairy stock, the cladodes impart a distinctive flavour to milk and
butter, and these products are often highly desired (Brutsch and Zimmermann 2000).
Cactus pears may be planted on the contour in the veld to enable the grazing animals to
utilise both the veld and the cactus plants. During periods of drought, the succulent
cladodes enable the animals to make better use of the dry veld. When planted on the
contour the plants also serve as windbreaks, reduce run-off and in this way conserve the
soil and water (Brutsch and Zimmermann 2000). Cactus cladodes can be fed to livestock
as fresh forage or stored as silage for later feeding (Castro et al. 1977).
Plantings of spineless cacti for use as fodder (i.e. harvested) or as forage (i.e. directly
browsed by livestock or wildlife) have been developed in Sicily and North Africa since
the mid-19th century with the purpose of stabilising the fodder resource in the arid and
semi-arid zones where feed shortage has always been a sub-permanent limiting factor in
livestock production. The establishment of fodder cacti is thus a kind of drought-
insurance in dry regions (Guastella 1913; Cattier 1934; Abramo 1935; Musmara 1937;
Cordier 1947).
Cactus pear plantations can be utilised in three different ways, namely, (i) as part of the
daily feed ration e.g. in dairy operations, (ii) as supplementary feed from the end of the
growing season to the onset of the next growing season, when rangelands are chronically
deficient in green forage, protein, carotene and phosphorus and lastly, (iii) as buffer feed
reserve for times of acute scarcity, in the event of prolonged droughts which may last 1 to
3 years (Le Houérou 1982; 1986; 1989a,c). Cactus feed i.e. cladodes aged 1-3 years, is
21
high in water (75-85%) in summer and early Autumn and (85-90%) in winter and spring;
it is also rich in sugars, pro-vitamin A and vitamin C, but poor in nitrogen (3-4%)
(Monjauze and Le Houérou; 1965). The digestibility of cactus pears also decreases with
age. When fed as an exclusive diet fresh cactus pads cause diarrhoea after about six
weeks for cattle and eight weeks for sheep. Their use as a single feed for emergency
survival rations should thus not exceed these periods. The diarrhoea can easily be
prevented and cured by adding to the cactus the equivalent of approximately 1% of the
animal live-weight in dry roughage, straw or hay (Cordier 1947).
The harvesting of fodder using the cut-and-carry method reduces or prevents wastage.
There is more risk in overuse in plantations where direct grazing is allowed. Cladodes are
given to herded animals either in the evening when returning to the pen or in the morning
before being set out to graze. The glochids present in spineless cacti are softened by
saliva and become harmless in the mouth and further down in the digestive tract. The
stand is exploitable after 4-5 years and fully-grown after 7-8 years. When rationally
managed, some remain productive for more than 50 years (Barbera 1984).
For fodder production a distinction can be made between blue-cladode cactus and green-
cladode cactus. In the past only the blue-pad type was recommended for fodder
production. Over the last few years, research has shown that some of the green-cladode
types could also be used as fodder plants. The blue-cladode cactus may have many
advantages over the green-cladode type. The most important advantage is that they are
resistant to cochineal and more drought resistant. The blue-cladode type of cactus pear is
however less palatable and yields less than the green-cladode type. There are three
recognised cultivars of the blue-cladode cactus namely, Robusta, Monterey and Chico.
Robusta and Monterey yield more, while Chico is more cold resistant (De Kock 1980).
Opuntia plants are highly efficient in the use of water and withstand dry periods and
extreme heat. These traits make them highly promising for soils poor in nutrients and
with limited water supply (Silva and Aceveda 1985). In relation to the management of
stock feeding, it was determined that the use of cactus pear cladodes in the feeding of
22
growing sheep improves the efficiency of drinking water by 30%. On the other hand, the
high productive potential of the cactus pear (Opuntia ficus-indicai, under water deficient
conditions, makes it an important feeding resource in Mediterranean zones where it can
be used to supplement dairy and meat-producing livestock, fed mainly on rangeland
(Azócar and Rojo 1991; Azócar 1992; Azócar et al. 1996; Ben Salem et al. 1996;
Santana 1992).
Santana (1992) reported a yield (fresh) of 106.9 to 205.0 ton per hectare per year
(approximately 16 to 31 ton ha-! year"! of dry matter), according to the geographical zone,
type of soil, fertiliser application, plant population and association to other crops. In
Chile, recorded yields of cladodes ranged from 13 ton per hectare per year of dry matter
in not very dense crops that only covered 30% of the land to 28-30 ton per hectare per
year in simulated conditions of density, watering and good fertilisation. Advantages of
the cactus pear include high biomass yield, high palatability and nutritive value,
evergreen habit, drought resistance, salinity tolerance and soil adaptability (Monjauze &
Le Houérou 1965; Le Houérou, 1992). This species has a high ash (260 g kg-! DM) and
water contenr (926 g kg" fresh weight), and low crude protein (58 g kg" DM). Ben
Salem et al. 1996 Monjauze & Le Houérou 1965; Le Houérou (1992) reported that
drinking water consumption by sheep is substantially reduced as the level of cactus pear
Increases.
2.10.3 Cactus pear as vegetable
The nutritional value of "nopalitos" (diced young cladodes ) is similar to that of many
vegetables, they contain mostly water (88-95%), some carbohydrates (3-7%), and
minerals (about 1.3%, mainly Ca). Like most vegetables, nopalitos are low in proteins
(about 1%) and fibre (about 1%, which is still more than twice that of lettuce) (Rodriquez-
Félix and CantweIl 1988). Nopalitos are less nutritious than spinach, but more nutritious
than lettuce (Cantwell1991).
23
2.10.4 Cactus as industrial crop
Cactus pear is very important as an industrial crop.
2.10.4.1 Cochineal
Cactus pear is an important industrial crop for the production of red dye from cochineal
insects. The carminic acid can be used as a biological stain for microscopy as well as a
dye for fabrics and foods (Nobel 1994).
2.10.4.2 Processed food
Nopalitos can be sold as processed food, including pickled nopalitos, various salads, and
cooked dishes. Fruits can be processed into fruit juices, concentrates, jams and jellies.
Queso de tuna (cheese of cactus pear) is also produced. Miel de tuna ((honey of cactus) is
another popular fruit product (lngles et al. 1993).
2.10.4.3 Medicinal products
Cactus pears are reported to improve the glucose control in humans, can reduce the blood
sugar levels and increase insulin activities under hyperglycaemic conditions. The sap
from the cactus c1adodes can be used in first aid and cosmetics similar to the Aloe vera
plant. A portion of the c1adodes is cut, crushed and the juice squeezed onto a cut, burn or
bruise. Ground or pureed young cladodes are used as a laxative and also as a remedy for
diabetes. In Central Africa, the sap from the c1adodes also serves as a mosquito repellent
(Inglese et al. 1993).
2.10.5. Uses of cactus pears to combat desertification
Cactus pear, as drought and erosion tolerant plant, can be used to slow and direct sand
movement, enhance the restoration of the vegetation cover and avoid the water
destruction of the land terraces built to reduce run-off. The cactus pear plant can be used
24
in combination with cement barriers or cut palm leaves to stop wind erosion and sand
movement. It will fix the soil and enhance the restoration of the vegetative plant cover
(Brutsch and Zimmermann 1993).
2.10.6 Anti-erosion hedges
Cactus pears are often used as defensive live hedges for the protection of gardens and
orchards throughout North Africa and parts of Italy and Spain. Cactus pear hedges play
an important role in landscape organisation when established in double rows. Cactus
hedges also play a major role in erosion control and land-slope partitioning, particularly
when established along contours. Moreover, hedges are physical obstacles to run-off,
favouring silting and thus preventing regressive erosion (Monjauze and Le Houérou
1965). Another role of cactus pear plantation is for runoff and erosion control and
watershed management. Planting cactus pear in degraded arid and semi-arid lands is one
of the easiest, quickest and fastest ways of rehabilitating them (Le Houérou 1982).
Recently, a cactus cladode extract was tested to improve water infiltration (Sáenz et al.
2004).
25
Chap ter 3
Study area and experimental procedures
3.1 Location
This study was conducted on the farm named Welgegund (28° 53' 5; 26° 56' E) near a
small town called Verkeerdevlei, 90 kilometres northeast of Bloemfontein.
3.2 Climate
The Glen weather station was used in this study to represent the climate of the
experimental plot because it has data of more than 70 years. Other climatic data used in
this study was obtained from a new weather station put up on January 2001 near the study
area. Long-term data used was obtained from Glen weather station and the national
climatological weather database of the Institute for Soil, Climate and Water of the
Agricultural Research Council (ARC).
3.2.1 Temperatures
Extreme temperatures beyond optimum are bound. to affect production potential of
different plants. According to Botha (1964), the average maximum temperatures for Glen
are 23.8°C, 20.2°C and 17.SoC for April, May and June respectively over the long-term
(Table 3.1). The average minimum temperatures are 7.4°C, 2.4°C and -1.3°C over the
long-term for Glen for April, May and June respectively (Botha 1964). The monthly
average maximum temperatures for April, May and June of 16.3°C, 20.1°C and 26.3°C in
the 2001/2002 growing season and 27.1 °C, 20.4°C and 17.9°C in the 2002/2003 growing
season respectively, recorded during the study were not abnormal (Figure 3.1). During
the study, the recorded average monthly minimum temperatures of -O.4°C, -3.3°C and -
O.l°C in 2001/2002 growing season were below the long-term levels. During the
2002/2003 growing season the monthly minimum temperatures of 10.1°C, 2.1°C and
26
2.9°C for April, May and June were recorded. These records were not unusual when
compared to the long-term readings (Table 3.1).
Table 3.1 The long-term average temperatures of Glen for the different months
(National climatological weather database of the Institute for Soil, Climate
and Water 1922 - 1990).
Average Average Average Av.erage grass
Month maximum minimum temperature (0C) minimum
temperature (0C) temperature (0C) temperature (0C)
July 17.3 -1.6 7.7 -4.4
August 20.4 0.7 10.5 -2.3
September 24.5 4.8 14.4 2.1
October 27.1 9.2 18.0 5.9
November 28.1 11.7 19.9 8.8
December 30.0 13.9 21.9 11.1
January 30.6 15 22.7 12.2
February 29.7 14.6 22.0 12.1
March 27.2 12.3 19.7 9.8
April 23.8 7.4 15.5 4.7
May 20.2 2.4 11.4 0.0
June 17.5 -1.3 7.9 -3.8
27
A
IT 40.0
CL... 30.0 - - ........C1I l!OlI9
..:.:..l. 20.0 - ~Cl! '*
C1I 10.0
0. =..-....-...-....-..-
E 0.0 -
C1I
I- -10.0
Jul Aug Sep Oet Nov Dec Jan Feb Meh Apr M ay Jun
Month
Ave temperature .... .... Ave max temperature Ave min temperature
B
- 40.0o
0_ 30.0
.. ... - ... _=Q). ~ ... """" .... - - .... "O!o
.:... 20.0 _ .....:l -'" - -"-" - - - ~l1li< - ..Cl! 10.0 =-------'-....._êaii.E 0.0 ~ ~ --..-..Q.). .......-10.0
Ju I Aug Sep o ct Nov Dec Jan Feb M ch A pr rliray Jun
M on th
Ave temperature - .... Ave max temperature Ave min temperature
C
30.0
U 25.0
0._. ... ... ....C1I 20.0 ...'"
..:.:-.l 1 5.0cu 1 0 .0 »:
C1I .,."a. 5.0 ~
E
C1I 0.0 ./
I-
-5.0
J u I Aug Sep o ct Nov Dec Jan Feb Mc h Apr May Jun
Mo nth
Ave temperature .... .... A ve m ax tem perature Ave m in tem perature
Figure 3.1 Average temperatures COC) at Weigegund for the 2001/2002 (A), 2002/2003
(B) and 2003/2004 (C) growing seasons.
28
3.2.2 Rainfall
The experimental site is located in a summer rainfall area. The probability of rainfall
higher than 50% is expected from October to April. The highest rainfall of 85.2 mm
occure in March. The highest average raindays of 10.1 is also in March. The total rainfall
of 677 mm recorded during the 2001/2002 growing season (Figure 3.2) was higher than
the long-term means (547.5 mm) for Glen (Table 3.2 and Figure 3.2). The total rainfall of
93.7 mm recorded for April, May and June during the first season of the study
(2001/2002) was also higher than the long-term means for the same months. During the
2002/2003 growing season, the total rainfall of 484.1 mm was lower than the long-term
levels for Glen. The total rainfall of 5.3 mm for April, May and June received during the
2002/2003 growing season was far lower than the long-term meansfor the same months.
Table 3.2 The long-term rainfall characteristics of Glen for the different months
(National Climatological weather database of the Institute for Soil, Climate
and Water 1922 - 1990)
0/0 Average raindays
Month Average rainfall Reliability 1914 -1964 (Botha
1964)
July 8.7 20.63 2.1
August 1l.8 18.13 2
September 19.1 20.68 2.6
October 47.1 5l.15 5.5
November 64.3 52.41 8.2
December 66.5 5l.55 8.1
January 8l.8 58.01 9.8
February 82.4 57.81 9.6
March 85.2 56.15 10.1
April 52.3 51.34 6.4
May 19.3 36.01 4.6
June 9.5 27.82 2.0
29
A
- 200E
-E 150
:! 100
e
ra 50
0::
0
Month 1:::·:::·:::·:::::::::1 Long-termaverainfall
-Total rainfall
B
100.--------------------------------------------,-
Ê OO~--~------------~-
§.OO+----I---+-------
oef! 40+--+--~--
l}_ 20 +---1----
o -t---""--r-
IVIonth ~=L..Irr..oIII"::!"t;;;IIIIIIQ~rnrLtcrn"l "'.D ra·nf'C..l.1..
-Tdaranfal
Figure 3.2 Long-term rainfall (mm) for Glen and total rainfall (mm) at Welgegund for
the 2001/2002 (A) and 2002/2003 (B) growing seasons.
30
3.3 Soil
The soil in the study area was a sandy loam of the Valsrivierform (Aliwal family-11220)
(Soil Classification Working Group 1991). The average soil texture for 0-300 mm, 300-
800 mm and deeper than 800 mm were 32%, 54% and 56% clay respectively. The
decrease in sand percentage, phosphorus and zinc and increase in clay percentage,
electrical conductivity (EC), pH, Ca, Mg, K and Na with depth of the soil is not unusual
(Table 3.3). Soil samples for laboratory analysis were collected from the three different
horizons (0 - 300, 300 - 800 and >800 mm). Samples for analysis were obtained from
Block A and Block B using a soil auger. The different blocks will be discussed in detail
under the experimental layout (Fig. 3.3). According to Wessels (1988), the optimal levels
of macro-elements in the soil for cactus plants should be 150 mg kg" for K, 12-15 mg kg-
I for Pand 80-100 mg kg-! for Mg. The values for K and Mg (Table 3.3) were above the
recommendations while P was low compared to the record provided by Wessels (1988).
Table 3.3 presents the percentage clay, percentage sand, electrical conductivity, soil
acidity level, calcium, magnesium, potassium, sodium, phosphorus and zinc at different
depths.
Table 3.3 Laboratory soil analysis for sand, clay, electrical conductivity (EC), soil
acidity level (pH), calcium (C), magnesium (Mg ), potassium (K), sodium (Na),
phosphorus (P) and zink (Zn) for different depths in the experimental site at
Welgegund.
Depth Clay Sand EC pH Ca Mg K Na P Zn
(mm) % % mêrn' mg kg mg kg" mg kg" mg kg" mg kg" mg kg" mg kg"
1
Profile
32.00 68.00 12.50 4.40 761.50 324.50 350.00 31.00 9.52 0.45
(0 -300)
Profile
54.00 46.00 19.00 5.95 1823.50 920.50 106.00 96.50 l.04 0.38
(300 - 800)
31
(>800)
56.00 44.00 61.00 7.65 9298.50 1430.50 144.00 232.00 0.18 0
3.4 Experimental procedure
The experiment was a randomised block design consisting of three treatments (fodder,
fruit and scozzolatura) and 11 cultivars, replicated twice on sixty-six plots. Each plot
consisted of 20 plants, planted in two rows of which 10plants were randomly selected,
marked and used as data plants. The field experimental layout is illustrated in Figure 3.3.
The plant density was 1 000 plants per hectare. The numbers represent different treatment
combinations that are presented in Table 3.4.
BLOCK A
BLOCKB
Figure 3.3 Experimental layout of the different treatments In two blocks.
32
Table 3.4 The different treatment combinations
Block A Block B Treatment combinations
Plot Treatment Plot Treatment Treatment Cultivar Treatment
combination combination combination
1 24 1 25 1 Nudosa Fruit
2 18 2 29 2 Nudosa Fodder
3 2 3 3 3 Nudosa Scozzolatura
4 20 4 32 4 GynU10 Carpo Fruit
5 9 5 22 5 GynU10 Carpo Fodder
6 7 6 l5 6 GynU10 Carpo Scozzolatura
7 3 7 20 7 Morado Fruit
8 33 8 31 8 Morado Fodder
9 28 9 16 9 Morado Scozzolatura
10 17 10 28 10 Zastron Fruit
II 5 Il 4 Il Zastron Fodder
12 30 12 6 12 Zastron Scozzolatura
13 14 13 9 13 Algerian Fruit
14 31 14 2 14 Algerian Fodder
15 26 15 1 15 Algerian Scozzolatura
16 27 16 8 16 Roedtan Fruit
17 16 17 30 17 Roedtan Fodder
18 32 18 12 18 Roedtan Scozzolatura
19 22 19 17 19 Torrnentosa Fruit
20 25 20 18 20 Torrnentosa Fodder
21 19 21 21 21 Torrnentosa Scozzolatura
22 21 22 27 22 X28 Fruit
23 15 23 5 23 X28 Fodder
24 l3 24 26 24 X 28 Scozzolatura
25 23 25 13 25 Sicilian fig Fruit
26 29 26 23 26 Sicilian fig Fodder
27 8 27 33 27 Sicilian fig Scozzolatura
28 11 28 11 28 Van As Fruit
29 4 29 7 29 Van As Fodder
30 6 30 24 30 Van As Scozzolatura
31 1 31 10 31 Monterey Fruit
32 10 32 14 32 Monterey Fodder
33 12 33 19 33 Monterey Scozzolatura
33
3.5 Collection of plant material
Plant material (one-year-old cladodes) used (Fig. 3.4) during the study was collected on
the 8th of August 2001 from Guillemberg (Polokoane) in the Limpopo province. Cladodes
from different cultivars were numbered as a way of identification (Fig. 3.5). Cladodes
were washed with Parathion to reduce possible incidences of infection before planting.
Figure 3.4 The one year old cladodes used as planting material
34
Figure 3.5 Numbering of cladodes from different cultivars
3.6 Cultivars and treatments
Two Opuntia species used in this study were Opuntia ficus-indica and 0. robusta. The ten
cultivars for the first-mentioned species were Algerian, Gymno Carpo, Morado, Nudosa,
Roedtan, Sicilian Indian fig, Tormentosa, Van As, X28 and Zastron. Monterey was the
only cultivar used for 0. robusta. The cultivars used in this study were selected on the
basis of their adaptability and production potential according to research and literature.
Opuntia ficus-indica is believed to produce higher cladode production than 0. robusta. It
can be used either for fruit or cladode production. Opuntia robusta is traditionally a fodder
plant compared to 0. ficus-indica.
35
• In the fodder treatment all the cladodes (previous seasons' cladodes ) were pruned in
winter. The idea was to stimulate production of more cladodes than fruits.
• Fruit treatment involved minimum pruning of cladodes to keep the plant in shape and
keep it below 2 m height as tall cactus plants would make harvesting difficult.
• In the scozzolatura treatment all the reproductive buds were removed during the first
flush. In winter the pruning was performed in the same way as the fruit treatment. The
main aim of scozzolatura treatment was to produce a late crop and stimulate vegetative
growth.
3.7 Liming and fertilisation
Liming to raise the soil pH, as per laboratory analysis used during the study was 4 tonnes
(Dolomite lime) per hectare. Superphosphate added at 300 kg per hectare, while 75 kg per
hectare of N-fertiliser was applied before establishment. It was only possible during the
study to fertilise the plants at establishment because a long period of drought made it
impossible to carry out topdressing.
3.8 Planting and spacing
Cladodes were planted on the is" October 2001 on a deeply tilled and well-disced soil.
Each plot consisted of2 rows with 20 plants (of which only 10 were used as data plants).
The cladodes were spaced 5m apart between rows and 2m apart within the row (Fig. 3.6).
The cladodes were planted upright, one-third into the soil (Fig 3.7). The row direction was
North-South.
36
Figure 3.6 The spacing of cladodes in the field during planting
37
3.9 Weeding
A tractor drawn disc cultivator was used to remove the weeds between the rows to reduce
competition for water and nutrients. Chemical weed control in the third season of the
study was done using glyphosphate. To ensure that the chemical did not reach the plants,
the cactus plants were covered before spraying the herbicide.
3.10 Data collection
Collection of data was carried out mostly in the second growmg season (2002/2003)
because the plants were allowed to establish in the first season (2001/2002) while in the
winter of 2003 they were killed by frost. The relationship between growing season, plant
age and activities are summarised in Table 3.5. Data collection can be divided into three
parts, namely: vegetative measurements, reproductive measurements and laboratory
measurements. It was not possible to calculate means from the data because of the big
difference in the production between the second and third seasons. After the plants have
matured (3 years) the production difference would be constant based on age of the plants
and climatic conditions.
38
3.10.1 Vegetative measurements
Vegetative measurements comprised plant width, plant height, number of cladodes on the
plant before pruning, number of cladodes removed by pruning, cladode percentage dry
matter content, cladode fresh mass, cladode dry mass, cladode dry yield, phenology and
frost damage. Only 10 data plants per treatment or plot were chosen randomly for each
measurement from the total of 20 plants planted.
3.10.1.1 Plant width
This measurement was carried out to monitor horizontal vegetative plant development
and enable the recommendation of a specific within-row planting distance for the climatic
region. A measuring tape was held horizontally alongside the plant in the row so that the
end of the measuring tape was in line with the starting point of the plant and the
measurement was taken. The operation was carried out in winter prior to pruning.
39
Table 3.5 The relation between growing season, plant age and activity at welgegund
Growing season
Months
Jul Aug Sep Oet Nov Dee Jan Feb Mar Apr Ma)' Jun
1/7/01 - 30/6/02 Plant date Remove
buds
1/7/02 - 30/6/03 Vegetative Reproductive Reproductive Harvest Harvest
data data data fruit fruit
Frost damage Frost damage
1 Year old
1/7/03 - 30/6/04 Frost damage Frost
damage
2 Years
old
40
3.10.1.2 Plant height
This measurement is necessary to indicate the vertical vegetative growth rate of cultivars
in the same climatic region. A measuring tape was placed next to the plant and the height
from the soil to the highest point of the plant was measured.
3.10.1.3 Number of cladodes on the plant prior to pruning
This measurement is an indication of the relative comparative vegetative growth rate of
the different cultivars. All the cladodes per plant (except the primary cladode ) were
counted in winter before pruning. However, cladodes of different cultivars may not be of
same SIze.
3.10.1.4 Number of cladodes removed by pruning
This practice is performed in order to determine how many cladodes are removed as
fodder for livestock or for purposes of plant material. After pruning in winter, all the
cladodes pruned per plant were counted.
3.10.1.5 Cladode mass
This measurement is used to determine individual cladode mass where the average
cladode mass per plant was calculated after weighing all pruned cladodes.
3.10.1.6 Clad ode dry mass yield
.The measurement is calculated to determine what the cladode yield (kg ha -1) could be.
The values were calculated by multiplying the cladode dry mass yield (kg) per plant with
the number of plants per hectare.
41
3.10.1. 7 Percentage frost damage
The values expressed as percentage were obtained by observing and noting the damage
caused by frost on cladodes and used to indicate difference in frost damage between
cactus pear cultivars. The percentage damage to plants was based on whether the damage
was 25%, 50%, 75% or 100%. Frost damage was observed and recorded three times on
2nd August 2002, 4th October 2002 and 14th October 2003.
3.10.2 Reproductive measurements
Reproductive measurements cover the following: phenology, number of fruits per plant
and fruit yield per plant. The average fruit measurements of only 10 data plants per
treatment were taken. The plants were randomly chosen from the total of 20 plants
planted in each treatment or plot.
3.10.2.1 Phenology
The time is determined when flower and leaf buds form, when flowering occures and
fruit development, in a given climatic region. The average date, expressed asn weeks of
the month, was observed and noted. Flower and leaf buds can be easily distinguished
when they are approximately 5 mm long.
3.10.2.2 Removal of the buds
Removal of the flowering buds from all the plants in the first year of plant development
was performed on the is" November 2002. All the reproductive buds were removed
during the first flush. This was done to ensure a better establishment.
42
3.10.2.3 Number of fruits
This measurement is used to determine fruit yield (plant -I) for the different cultivars. The
number of fruits per plant was obtained by counting the fruits during harvesting. The
operation was performed on the zs" January 2003 for all other cultivars except X28 and
Zastron. Zastron's fruits were harvested on 6th March 2003 because the fruits ripened
later in the season.
3.10.2.4 Fruit yield
The value is useful in determining the fruit yield per plant or per hectare for each cultivar.
The average fruit mass per plant was determined and then multiplied by number of plants
per hectare (1 000) to obtain fruit yield per hectare.
3.10.2.5 Laboratory measurements
Laboratory measurements include fruit mass, fruit width, fruit length, flower- end depth,
peelability index, peel thickness, pulp mass, T.S.S (Brix %), number of mature seeds,
number of aborted seeds, mass of dried developed seeds, mass of dried aborted seeds and
peel mass.
3.10.2.6 Fruit mass
The value is useful in determining fruit-yield and quality analysis. A laboratory electronic
scale was used to obtain the weight of individual fruit from the different cultivars. The
average fruit mass per plant and per cultivar was calculated with and without peel.
43
3.10.2.7 Fruit width
A Vernier caliper was used to measure the width of individual samples of harvested fruits
from different cultivars. This value is useful in determining the size and shape of the
fruit.
3.10.2.8 Fruit length
A Vernier caliper was used to measure the length of individual samples of harvested fruit
from the different cultivars. This value is useful in determining the size and shape of the
fruit.
3.10.2.9 Flower-end depth
The back -end of a Vernier calliper was used to measure the depth of the bell of the flower
(calyx end) on the individual sample of fruits. This value is a genetic characteristic of
cultivars, but is also influenced by environmental conditions e.g. the longer the fruit-
developing period, the shallower the calyx end depth.
3.10.2.10 PeelabiIity index
This measurement determines the difference in ease of peel removal of different cactus
pear cultivars. It has a bearing on fruit quality and marketing potential. The peel of a fruit
was cut with a knife and removed from the pulp. The peelability index was categorised as
good or poor.
3.10.2.11 Peel thickness
The measurement is necessary in order to determine the proportion of the peel to the
pulp. Individual peel thicknesses of the different cultivars were determined using the
Vernier caliper. The peels were measured around the center of the fruit.
44
3.10.2.12 Peel mass
This measurement gives an indication of the ratio of peel mass to edible pulp mass.
Individual peel masses of the different cultivars were determined using the laboratory-
electronic scale.
3.10.2.13 Percentage dry material content of cladodes
This measurement is necessary in order to determine the dry material yield. The fresh wet
mass of a sample of cladodes was determined before it was dried in an oven at 100°C.
From these differences, the dry matter yields were calculated.
3.1.2.14 Cladode fresh mass
This measurement is necessary to determine the mass of plant material removed annually
with pruning. During pruning the mass of all pruned cladodes from the different cultivars
was obtained using a Digital platform scale. The fresh mass yield was expressed in
kilograms.
3.10.2.15 Peel and pulp colour
The measurement is required to determine the difference in peel and fruit colour of the
different varieties. The fruit colour may determine marketing potential of a specific
variety. When the peel has been separated from the pulp, the colour of both peel and pulp
was determined visually.
3.10.2.16 Total soluble solids (TSS)
Total Soluble Substances provide an indication of the sugar content of fruits from
different cactus pear cultivars. In this study TSS, in Brix %, from individual cactus pear
45
cultivars was determined using a hand refractometer. The average TSS of only 10 fruits
from each treatment was taken.
3.10.2.17 Number of developed seeds
When seeds from fruits of different cactus pear cultivars had been separated from the
pulp using a juice extractor and dried, developed seeds were separated from the aborted
seeds and counted. The number of seeds is an indication of fruit quality. The seeds from
only 10 fuits per treatment were taken for the seed measurement.
3.10.2.18 Number of aborted seeds
The number was obtained by separating the dry aborted seeds from developed seeds and
counting them to obtain the number. The number is an indication offruit quality.
3.10.2.19 Mass of mature and aborted seeds.
Dried developed and aborted seed mass from each fruit was obtained by using the
laboratory electronic scale.
46
Chapter 4
Evaluation of cactus pear cladodes
4.1 Introduction
Cactus pear is used worldwide either as a dry-land pasture or as a cash crop. However,
little horticultural research has been devoted to its productivity under different
environmental conditions and management systems (Inglese 1992). Cactus pear is
increasingly commercialised and there is therefore, a need to evaluate different
characteristics to improve the farmer's selection of cultivars and productivity (Oelofse
2002). On the other hand, Opuntia production is extremely variable, because yield
depends on orchard design and management rather than on prevailing environmental
constraints (Pimienta 1990; Barbera et al. 1991). Differences in planting material, related
to root and canopy development, often account for discrepancies in yield potential during
the first four to five years after planting (Barbera et al. 1991). The production potentiah of
selected cactus pear cultivars was Therefore, evaluated for two and three year old plants
in this study.
4.2 Results and discussions
Encompassed under this heading are plant height and width, number of cladodes on the
plant before pruning and number removed by pruning, cladode mass and cladode dry
matter content, cladode yield and frost damage. Cladodes were not evaluated in the first
growing season (2001/2002) because the plants were still young. No pruning took place
IN the first growing season, the plants were only allowed to grow and 'establish well.
Unfortunately, over the third growing season (2003/2004) the plants were killed by frost
and only A few measurements were carried out. Most of the records in the present study
were, therefore, obtained in the second season (2002/2003).
47
4.2.1 Plant height and width
The plant height and width measurements displayed in Figures 4.1 and 4.2 were obtained
in the second growing season (2002/2003) of plant development. In the third growing
season, it was impossible to carry out height and width measurements because the plants
were killed by frost. This will be discussed in detail under point 4.2.7. The treatments did
not differ significantly (P>0.05) from each other in terms of height and width (Fig. 4.1).
The P-values and least significant differences (LSD) for the different treatments and
cultivars (P~0.05 level of significance) are presented in Table A. I.
--E:c 0.30
Ol
..ê 0.20
"cC: 0.10
ca
.s::::
~ 0.00
~
IIIIIwidth
Treatment Dheight
Figure 4.1 Average plant width (m) (LSD 0.05 = 0.022) and height (m) (LSD 0.05 =
0.0285) for the different treatments determined for two-year-old plants.
Such results were expected because after only two years of establishment, the treatments
should not show an effect. However, a significant difference (P<0.05) existed between
some cultivars in terms of height and width (Fig. 4.2). Although the greatest plant widths
attained by Roedtan, Morado and Algerian were not significantly (P>0.05) different from
each other, they were greater (P<0.05) compared to Gymno Carpo, X28, Monterey and
48
Tormentosa. The lowest average width of 0.12 m was recorded for Tormentosa with the
highest average width of 0.26 m recorded for Morado in this study. The greatest height
attained by Zastron was significantly higher (P<0.05) than Van As, Sicilian Indian fig,
Gymno Carpo, X28 and Tormentosa. The lowest height attained by Tormentosa was only
not significant (P>0.05) when compared to Gymno Carpo, Monterey and X28. All
cultivars grew more in height than width, with the exception of Zastron which grew more
in width. The lowest average height of 0.16 m per plant was recorded for Tormentosa,
while the highest average width ofO.33 m was recorded for Zastron in this study.
---E 0.45..c:
C)
Cl) 0.30
..c:
'C
e 0.15
ns
..c:
'-C
~
IIIwidth
Cultivar o height
Figure 4.2 Average plant height (m) (LSD 0.05 = 0.0746) and width (m) (LSD 0.05
=0.0665) for the different cultivars for two year old plants.
In view of the results reported by Oelofse (2002), who evaluated among other variables,
plant height and width of ten cactus pear cultivars (5 years old) including Nudosa,
Gymno Carpo, Morado, Zastron, Algerian, and Roedtan, Zastron, Morado and Roedtan
attained greater height and width than other cultivars (Nudo sa, Gymno Carpo and
Algerian). This report is in agreement with the observations in the present study. In the
present study all eleven cactus pear cultivars under consideration attained more height
(0.16 - 0.26 m) than width (0.16 - 0.33 m) which is not in harmony with the findings of
49
Olelofse (2002) who reported more growth in width (2.08 - 2.51 m) than height (l.73 _
2.23 m) in all cultivars. As one could expect from five-year-old plants, Oelofse (2002)
reported far higher growth in height and width than those recorded in this study.
Unfortunately, there is limited literature available on the growth performance of young
cactus plants (1 - 3 years) to substantiate the findings reported in this study.
4.2.2 Number of clad odes on the plant before pruning
It was only possible to monitor this parameter twice during the study. In the first year the
plants had developed only 2 cladodes on average and as such no exact counts or pruning
were done. Over the first season the plants were only allowed to establish without any
pruning. The average number of cladodes on the plant before pruning during the second
season (Fig. 4.3) did not differ significantly (P>0.05) between the treatments. However,
there was a significant difference (P<0.05) between cultivars both in the second and third
seasons (Fig. 4.4). The highest number of cladodes per plant before pruning attained by
Zastron in the second year was higher (P<0.05) than those in all other cultivars, except
Morado, Roedtan, Algerian and Nudosa. The lowest number of cladodes per plant before
pruning, attained by Tormentosa was significantly lower (P<0.05) than in all other
cultivars, except for Monterey and X28. In the third year of plant development, Roedtan
attained a higher number of cladodes per plant (P<0.05) when compared to Monterey,
Tormentosa, Gymno carpo, Zastron, Algerian and X28 (Fig 4.4). The lowest number of
cladodes per plant was recorded for Monterey. Lack of literature about performance of
young cactus plant's (1 - 3 years) makes it difficult to compare the results obtained in this
study.
50
I/)
Cl)
'C
0 6.00
'C
n:! ...
.(...). '-. 4.00e::
0 -n
-:!
to.. a. 2.00
.Ccl)
E 0.00
::::I
Z oe~ ~0\.
Xo~ (1,1-0
'2JcP III 2nd season
o 3rd season
Treatment
Figure 4.3 Average number of cladodes (plant") in the second «LSD 0.05 = 0.1239) and
third season (LSD 0.05 = 0.152) before pruning.
I/)
Cl)
'Co
"C
-n('
:!7 -.)ë
ë .!!!
to.. a.
.Ccl) -
E
::::I
Z
.2nd year
D3rd year
Figure 4.4 Average number of cladodes (plant") in the second (LSD 0.05 = 0.4381) and
third year (LSD 0.05 = 0.9692) before pruning for the different cultivars
It is not surprising that Roedtan, Morado, Van As and Nudosa attained higher average
numbers of cladodes before pruning (Figure 4.4) because these cultivars did not suffer as
51
much frost damage relative to Zastron, Tormentosa, Algerian, Gymno Carpo and Van As
during the winter of 2002 (Figure 4.14). Roedtan, Morado and Van As also suffered
relatively less frost damage from the late frost (4th October 2002). This is discussed in
detail under point 4.2.7.
4.2.3 Average number of cladodes per plant removed by pruning
It was only possible to monitor this parameter once in 2002/2003 because in the first
season (2001/2002) the plants were still developing while in the third season (2003/2004)
all the cultivars were killed by frost. The average number of cladodes per plant removed
by pruning differed non-significantly (P>0.05) between the treatments. At a young stage
of plant development (1 - 3 years) there should be no difference between treatments with
similar management. The difference between treatments was expected later beyond the
third year when management differs according to each treatment.
The relative difference between the treatments shown in Figure 4.5 was not expected.
The observed discrepancy should have been made possible by the higher individual
contribution of certain cultivars over others in different treatments. The total average
number of clad odes per plant recorded for the fruit treatment (1.37) was largely due to the
contribution of Roedtan (12%), Zastron (11%), Algerian, Morado, Sicilian Indian fig and
Nudosa (10% each). Algerian and Morado contributed 9% each, Monterey 7% and X28
6%. Under fodder treatment, the attained total average number of cladodes removed by
pruning (1.30) was largely due to the contribution of Roedtan (12%), Zastron (11%),
Algerian, Morado, Nudosa and Sicilian Indian fig (10% each). Other cultivars'
contributions were 9% for Van As, 8% for Gymno Carpo and 6% for Tormentosa and
X28 each. Under Skozzolatura, the total average number of cladodes (1.26) removed by
pruning was largely the combined contribution of Roedtan, Morado and Zastron (33%)
and Sicilian Indian fig (10%). Algerian and Gymno Carpo contributed 9% each and
Monterey and X28 7% each. Under the three treatments (fodder, fruit and skozzolatura)
the contributions of Roedtan, Zastron, Morado and Nudosa was superb. The combined
1/13 ~~o »<
52
contribution of the above mentioned cultivars was higher in fruit and fodder treatments
(43%) than in skozzolatura (42%).
tA
~o "C 1.40Cl)
"C c:
ns ::::J
to) C. 1.30
..0... ..-.
'C-l) 'c-:
.Ec ~ 1.20Co
::::J -
Z
Treatment
Figure 4.5 Average number of cladodes removed by pruning (LSD 0.05 =0.2284) for each
treatment determined for two-year-old plants.
The number of cladodes per plant differed significantly (P<0.05) between some cultivars
(Figure 4.6). Morado and Roedtan had a higher number of cladodes removed by pruning
than other cultivars. However this was only significant (P<0.05) when compared with
Tormentosa, Monterey and X28. In view of the findings recorded by Oelofse (2002), on
the number of cladodes pruned from 5 year old plants, Morado and Roedtan attained
higher values than Zastron, Algerian, Roedtan, Nudosa, Gymno Carpo and other
cultivars. The values were 72.5, 72, 65.6, 56.6, 56.3, 47 and 22.9 cladodes per plant for
Morado, Roedtan, Zastron, Gymno Carpo, Algerian and Nudosa respectively. Such
findings agree with the present study. Roedtan and Morado had a higher average number
of cladodes removed by pruning (Figure 4.6), as these cultivars together with Nudosa and
Van As, did not suffer as much frost damage in comparison to Zastron, Tormentosa,
Algerian, Gymno Carpo and Van As during the winter of 2002 (Figure 4'.14). Roedtan,
Morado and Van As also suffered relatively less frost damage from the late frost (4th
October 2002). This is discussed in detail under point 4.2.7. The lower average number of
53
cladodes removed by pruning recorded for Nudosa compared to Roedtan, Morado and
Van As, could be associated with the relatively high late frost damage (2.33%) recorded
on 4 October 2002 (Figure 4.14). Roedtan, Morado, Van As and Nudosa suffered almost
equal frost damage during winter 2002 and attained an almost equal average number of
cladodes before pruning.
f/)
CJ)
'o0'0CJ)
'n0s c:: 2.00 --===:::J
o L- 1.50 -Ji:i:;:;:;~~.0... .-Cl...1..00
L- :
CJ) c..n:s:
. 0.50
.0
EO. 0.00
:::J-
Z
Cultivar
Figure 4.6 Average number of cladodes per plant removed by pruning
(LSD 0.05 = 0.4925) for each cultivar.
4.2.4 Average cladode fresh mass
The cladode fresh mass per plant was determined only in the second season (2002/2003).
In the first season (2001/2002) it was not evaluated because the plants were still young. It
was impossible to evaluate cladode fresh mass for the third growing season (2003/2004)
because the plants were killed by frost. The treatments did not differ significantly
(P>0.05) from each other in terms of the average cladode fresh mass (Fig. 4.7). Slightly
higher values, although non-significant (P>0.05) were obtained for scozzolatura than for
other treatments. The contribution of the different cultivars to the overall cladode fresh
mass recorded for scozzolatura was as follows: 0.07g (19%) for X28, 0.05g (14%) for
Monterey and Nudosa (each), 0.03g (8%) for Morado, Roedtan, Tormentosa and Sicilian
Indian fig (each), 0.02 (5%) for Algerian, Gymno Carpo and Zastron (each), and 0.025
(6%) for Van As. The cultivars X28, Montery and Nudosa were responsible for higher
cladode fresh mass attained by scozzolatura over fodder and fruit treatments.
The different cultivars differed significantly (P<0.05) in terms of average cladode fresh
mass (Fig. 4.8). Roedtan attained the highest (P<0.05) cladode mass compared to other
cultivars. Morado also had a significantly high (P<0.05) cladode fresh mass than
Monterey, Nudosa, Sicilian Indian fig, Tormentosa and X28. The lowest cladode mass,
recorded for Tormentosa, was only significant (P<0.05) when compared to Roedtan,
Morado, Gymno Carpo and Algerian. Oelofse (2002) reported a higher cladode mass for
five-year-old plants (l.09 - 2.8 kg) than those reported in the present study. These
discrepancies could be due to the difference in age of the plants considered in the
different studies. Oelofse (2002) also recorded 1.36, 1.23, 1.18, l.17, 1.16, l.09 kg fresh
clad ode mass per plant for Nudosa, Algerian, Morado, Zastron, Gymno Carpo and
Roedtan respectively. Although Roedtan attained the highest cladode mass in the present
study among all cultivars, it recorded the lowest mass compared to other cultivars
according to Oelofse (2002). Surprisingly, Nudosa, which was not prominent in the
present study in terms of cladode fresh mass, performed excellently according to Oelofse
(2002). Roedtan and Morado recorded higher average cladode mass per plant because
they were not affected as much by frost as Zastron, Tormentosa, Algerian and Gymno
Carpo in winter during 2002/2003 growing season. They also suffered the least late frost
damage together with Monterey and Van As (Figure 4.14).
ss
C)
~-lA 0.020
clAu
E
.c ....
lA "
-- 0.010c:
CJ)
..~... cua.
CJ) 0.000
"C
0 oe'<.
"C
~ ~rft
U
Treatment
Figure 4.7 Average cladode fresh mass (kg plant -1) (LSD 0.05 = 0.0067) for different
treatments determined for two year old plants.
lA
clAu
E
.c ....-.
elA 'c-..... cu
lA Q.
CJ) C)
"C ~
0
"cC
-
u
U
Fig 4.8 Average cladode fresh mass (kg plant -1) (LSD 0.05 = 0.0518) for different
cultivars determined for two-year-old plants.
56
4.2.5 Average cladode dry mass percentage
This parameter was recorded in the second season (2002/2003) after the establishment of
the plants. In the first season (2001/2002) no data was collected because the plants were
too young. It was impossible to obtain data in the third season (2003/2004) because the
plants were killed by frost. The average cladode percentage dry matter per treatment (Fig
4.9) did not differ significantly (P>0.05). The observed difference between treatments,
although not significant (Fig. 4.9) is questionable because the three treatments received
similar treatments.
...-...
; 12%
~o-c. 9%
6%
Treatment
Figure 4.9 Average cladode dry mass (% plant -1) (LSD 0.05 = 2.27) for different.
treatments determined for two year old plants
The different cultivars' contribution to the total percentage dry mass recorded for
Scozzolatura was 12%, 11%, 11%, 10%, 10% 10%, 9%, 9%, 9%, 5% and 4% for
Zastron, Monterey, Morado, Nudosa, Roedtan, X28, Gymno Carpo, Sicilian Indian fig,
Van As, Algerian and Tormentosa respectively. It seems that all the cultivars except
Algerian and Tormentosa made a considerable contribution to the cladode dry mass yield
57
under Scozzolatura. Under fodder and fruit treatments, all the cultivars contributed
relatively equally to the total percentage dry mass.
Different cultivars did not differ significantly (P>0.05) in terms of cladode percentage
dry matter content (Figure 4.10). Cladode dry matter content of 8.01 and 7.96% recorded
by López-Garcia et a!. (1997) agreed with that of Algerian, Monterey, Sicilian indian fig
and X28. In this study a higher percentage dry mass for Gymno Carpo, Morado, Nudosa,
Roedtan, Van As and Zastron was recorded compared to that obtained by López-Garcia
eta!. (1997).
I/)
I/)
ns - 15%E ...-. I~ C 10%'C ~
I/) c.
Cl)
'C -~ 5%00'Cns
CJ
Cultivar
Figure 4.10 Average cladode dry mass (% plant -1) (LSD 0.05 = 6.3856) for different
cultivars determined for two year old plants.
4.2.6 Average cladode dry mass yield
The average cladode dry mass yield was measured in the second season (2002/2003). In
the first season (200l/2002), no data was gathered to allow plants to become well
establish. It was impossible to obtain data on dry mass yield of cladodes in the third
58
growing season because all the cultivars were severely damaged following severe frost,
except the mother cladodes. This record is well presented in 4.2.7.
The average dry mass yield per treatment did not differe significantly (P>0.05) between
treatments (Fig. 4.11). The different cultivars' contribution to the total dry mass yield
recorded for scozzolatura was 12%, 11%, Il %, 10%, 10% 10%, 9%, 9%, 9%, 5% and
4% for Zastron, Monterey, Morado, Nudosa, Roedtan, X28 Gymno Carpo Sicilian Indian
fig, Van As, Algerian and Tormentosa respectively. It seems that all the cultivars except
Algerian and Tormentosa made a considerable contribution to the cladode dry mass yield
under Scozzolatura. Under fodder and fruit treatments, all the cultivars contributed
relatively equally to the total percentage dry mass yield.
In contrast, some of the cultivars differed significantly (P<0.05) in terms of cladode dry
mass yield. Cladode dry mass yield attained byr Roedtan was higher (P<0.05) than that
of all other cultivars except that of Morado. Low cladode dry mass yields for Monterey
and Tormentosa was only significantly (P<0.05) different from those of Morado and
Roedtan. Morado, Algerian and Gymno Carpo recorded relatively higher dry mass values
than all other cultivars, except Roedtan. This parameter was not documented in most
research work on cactus pear. De Kock (1998) recorded a 3.27 (t ha") cladode dry mass
yield for 2920 mature plants (t ha") or 1.1 (kg ha") for each plant. By comparison, the
cladode dry mass yields attained in the present study were low. It is logical that low dry
mass values were recorded here as only a small cladodes (Fig. 4.4) were produced and
consequently few cladodes were pruned (Fig.4.6) per plant (from which dry mass was
derived).
59
0.2000
0.1000
0.0000
Treatment
Figure 4.11 Average cladode dry mass per plant (kg ha -I) for each treatment (LSD 0.05 =
0.1200) determined for two-year-old plants.
ti)
~ _ 0.200
E .......
e ;
"C a. 0.100
tI)'7
"ClC).ccu
o Ol 0.000
"C~
CU -
U
Cultivar
Figure 4.12 Average cladode dry mass per plant (kg ha-I) for each cultivar (LSD 0.05 =
0.1200) determined for two-year-old plants.
Higher average dry mass (plant kg ha") recorded for Roedtan and Morado was due to the
fact that these cultivars did not suffer much frost damage during winter 2002. They also
60
did not suffer more damage from late frost when compared to other cultivars except Van
As and Monterey (Figure 4.14).
4.2.7 Frost damage
Figures 4.13 and 4.14 illustrates the average percentage frost damage per plant for the
different treatments and cultivars observed on different dates (2/8/02, 4/1 0/02 and
14/9/03). The treatments did not differ significantly (P>0.05) in terms of percentage frost
damage. However, there was a significant (P<0.05) difference between some cultivars in
terms of frost damage. Zastron suffered more (P<0.05) frost damage than other cultivars
in the (2002/2003) growing season (2nd October 2002). Monterey attained the lowest
(P<0.05) frost damage compared to all other cultivars, except Zastron, Algerian and
Tormentosa at the first observation date (2/8/02). Nudosa suffered the most frost damage.
However, this was significant (P<0.005) when compared to all other cultivars except
Zastron and Sicilian fig at the second observation date (4/10/02). Zastron also suffered
more frost damage, which is significant when compared to all other cultivars except
Nudosa, Sicilian Indian fig and Monterey (Fig. 4.14). At the third observation date
(14/9/03), Monterey recorded the lowest (P<0.05) percentage frost damage compared to
other cultivars. All other cultivars, which were not significantly different (P>0.05) were
dead (except the mother cladode) when the last observation was carried out (2003/2004
growing season). Algerian, Sicilian Indian fig, Van As and X28 suffered higher frost
damage (100%) than other cultivars. Tormentosa and Roedtan (98%), Nudosa (97%),
Morado (96%) Gymno Carpo (95%) and Zastron (85%) were also greatly affected by the
frost.
61
~0- 100.00Cl,) ti)
C)CI,) 80.00
cEu."" g
c 60.00
cuCucu 40.00
.ë...-0 20.000.00
u,
Oe<"
<t:0C) []218/02
II1II4/10/02
Treatrrent 014/9/03
Figure 4.13 Average frost damage ( %) to cladodes measured at different dates (LSD 0.05
= 2.3312), October (LSD 0.05 = 1.186) and (LSD 0.05 = 6.649) for each
cultivar.
~- 1000
-I/)
CCl))"Cca C
l) 80
E 0 60
-ca
"Ccu
"Cu 40
I/) 0 20
0
L'
-
L- 0
+nveo ~~O .-_---,
"v'l>(;j CJ 2/1 0/02
1114/10/02
014/9/03
Figure 4.14 Average frost damage (%) to cladodes measured at different dates (LSD 0.05
= 17.007), (LSD 0.05 = 1.6329) and (32.0101) for each cultivar.
62
Opuntia cultivars are generally irreversibly injured at temperatures between -5 and -10°C
(RusseIl and Felker 1987: Nobel and Loik 1993). In Opuntias, the lack of freezing resistance is
probably not due to the lack of tolerance to cold temperature per se, but the range of day to night
temperatures, from 28°C down to -12°C in a single day, which does not allow the plant to
properly acclimatise (Gregory et al. 1993). Successive nights of low temperatures (Figures 5.16)
of -0.86 to -3.3 oe, -2.08 to -2.67°e, -0.61 to -1.37°e, -0.37 to -4.65°e, -3.15 to -4.79°e, and-
0.61 to -0.12°e for 5 days (7-12/5/2002), 2 days (9-11/6/2002) 4 days (16-20/6/2002), 6 days
(24-30/6/2002) and 6 days 2-8/7/2002 respectively were very injurious to the cactus pear
cladodes in this study. Another incidence of a drop in temperatures (-0 .12°e) and (-2. 06°e) on
the 2nd and 4th October of the same season, when young plants had resumed growth is believed to
have aggravated the degree of damage suffered by plants during winter.
Low night temperatures of -0.61 to -3.55°e for 4 days (27-31 May 2003), -0.2 to -
8.07°e for 25 days (4 to 30 June 2003), -0.94 to -6.2Soe for 20 days (Ol to 21 July
2003), -0.61 to -3.SSoe for 4 days (7 toll August 2003), -0.2 to -9.63°e for 6 days (14 to
20 August 2003), and -1.36 to -8.0Soe for 7 days (22 to 29August 2003) should have
been too much for the young cactus pear plants to withstand (Fig. 4.16). Nine out of the
11 cactus pear cultivars under study were killed in the winter preeeeding the third
growing season. The remaining two cultivars also suffered high frost damage (Monterey
40% and Zastron 8S%) where only some of the mother cladodes survived (Figure 4.16).
The reason why cactus pear cultivars were killed in the present study can be debated, as
there are successful cactus pear plantations in the central Free State and in the karoo. It is
believed that low temperatures did not single-handedly cause the death of the cactus pear
plant. A long spell of drought for 4 months (April? May, June and July) in 2002/2003
growing season could have a bearing on that as well (Figure 3.2). A long period of
drought coupled to successive nights of low temperatures below zero experienced several
times during the study (Figures 5.14), could have been too harsh for the young plants to
survive. Also high average maximum temperatures of 28.1, 30.1, 29.3 and 28.1 for
December, January, February and March respectively recorded in 2002/2003 growing
63
season, could have been detrimental to young cactus plants (Fig. 5.15). The 4.40 mm
rainfall recorded over three months (April, May and June) in 2002/2003 growing season
could have been inadequate to allow young plants to attain full development and
production. That amount of rainfall was far below the long-term levels (77.8mm) for the
same months. Of the 4.40 mm rainfall recorded for three months, 20% was received in
April while 80% was received in May. No rainfall was recorded in June and July. The
monthly summary of climatic data at the experimental site over 2001/2002 to 2003/2004
growing seasons is presented in Table A.2
When cultivation was carried out (3 times over the study period) to remove weeds
between the rows, it is believed that the disc implement cut some of the roots. Cut roots
were bound to reduce the capacity of the plants to take up water efficiently (lnglese and
Pace 2000). With some roots reduced, young cactus plants could find it hard to survive a
long period of drought Van der Merwe et al. 1997. It is well known that the cactus pear
plant is shallow-rooted. The cactus pear roots can spread horizontally up to 4 to 8 m from
the mother plant (Hills 1995; Drennan and Nobel 1998). According to Ramakatane
(2003), the root spreading can be as far as 1.5 to 1.7 m from the plant after only the first
season of planting. Given the long period of drought, Successive cold winter nights (third
season 2003/2004) (Brutsch 1997) and probable cutting of roots by cultivation, it is
possible that the plant available water was inadequate and as such plants stood no chance
of survival. The study was planned to continue beyond the third season after
establishment but unfortunately, it had to be terminated when most of the cultivars,
except the mother cladodes of some cultivars, died.
64
Figure 4.15 Water stressed one-year old cactus pear cladodes.
Figure. 4.17 Cactus pear plants killed by frost in the 2003/2004 growing season.
65
A
I/)
.~:::.:J.
E
0)
-0Eu._0)0E -
::::J
E
c
~
B
E
::::J
E
e
~
Day
Figure 4.16 The daily temperatures (oC) for May and June in 200112002 season (A) and
2002/2003 season (B) at Welgegund.
66
4.2.8 Conclusions and recommendations
Conclusions
This study has demonstrated that all the cultivars studied are able to attain more growth
in height than width in the young stage of development (1 - 3 years). It was evident that
the studied cactus pear cultivars would be killed by frequent successive nights of
temperatures below freezing point. Frost damage to young cactus pear could impact
negatively on both vegetative and reproductive yields. The findings about the cactus pear
cultivars based on their individual performance on different vegetative characteristics are
shown in Table 4.1.
This study was intended to continue beyond the third season but this was impossible
because the young plants of most cultivars were killed by frost in the third year. It is
therefore necessary that more research on performance and survival of young cactus pear
plants be carried out. In any endeavour to engage in cactus pear production for different
purposes, it is imperative that the site selected be not prone to heavy frost. A combination
of low temperature and soil-water stress could be detrimental to young cactus pear plants.
When mechanical weeding is carried out, great care should be taken to avoid cultivating
near the plants and consequently cutting the roots. The best method of weed control is
therefore chemical. This is very important during droughts as cactus plants in the arid and
semi-arid areas need to have a well-spread and developed root system in order to take up
small rain showers in the most efficient way. Timely weeding is necessary to avoid
competition between weeds and young cactus plants in the drier areas. Further research
work is a necessity to improve cold resistance characteristics in adapted cactus pear
cultivars. Another problem is the lack of data on young plants (1 to 3 years old). Most
findings are based only on full-grown plantations and there is, therefore, a need for
information on the performance of different cultivars over the first years of growth. It
would be wrong to reach a conclusion that cactus pear plantations can not be successful
in the Central Free State, or similar cold areas, whereas there are a lot of succssful fodder
67
and fruit plantations of cactus pear in the Free State. The success of cactus pear
(especially young plants) is a function of both management and climatic conditions.
Perhaps the whole dynamics of cactus pear plant development is not properly understood.
Table 4.1 Performance summary for the different cultivars.
Cultivar Height Width Cladode Cladodes Cladode Cladode Cladode Frost
number pruned fresh dry dry damage
mass mass mass
yield
Algerian ++ +++ ++ + ++ ++ ++ -
Gymno Carpo + +++ ++ + ++ +++ + +
Monterey + + + - ± + - -
Morado +++ ++++ +++ ++ +++ +++ ++ -
Nudosa ++ +++ +++ ± + ++++ ± -
Roedtan +++ ++++ ++++ ++++ ++++ +++ ++++ -
Sicilian fig ++ ++ ++ ± + ++ ± -
Tormentosa ± ± + - ± + - -
Van As + ++ +++ + + +++ + -
X28 ± + ++ - ± + ± -
Zastron ++++ ++ ++ + + ++++ ± ±
Key
Excellent ++++ Good ++ Poor ±
Very good +++ Satisfactory + Very poor
Surplus vegetative growth is only beneficial where one is looking at feeding it to
livestock (or as a source of planting material). For fruit production, it is important to have
a balance - fruit production plus new cladodes which will bear the following season.
68
Chapter 5
Evaluation of cactus pear fruits
5.1 Introduction
There is increasing interest in the major markets for the fruit of cactus pear where it
competes with some of the better known traditional fruits in the different regions of
southern Africa. Although cactus pears are already known to a broad cross-section of the
population in southern Africa, demand for good quality fruits can be expected to increase
rapidly (Brutsch and Zimmermann 1993). Mindful of this fact, it is imperative to direct
efforts to broaden the database about the crop.
5.2 Results and discussion
Included under results and discussion are phenological stages, number of fruits produced,
mass of fruits, total soluble solids, pulp colour, peelability index, harvest period, seed
number and seed weight.
5.2.1 Phenology
Basic phenological stages such as budbreak and 50% anthesis are presented in Table 5.1.
for the different cultivars It was only possible during the study to monitor this parameter
in the second season of plant development (2002/2003). In the first season (2001/2002)
the plants were too young to monitor phenological stages while in the third season
(2003/2004) all the plants were killed by frost, leaving only the mother cladode. The last-
mentioned problem is discussed fully in chapter 4. All the cultivars had a slightly later
budbreak when compared to the results reported by Oelofse (2002). Oelofse (2002)
reported early budbreak (week 2 in July - week 4 in August) as compared to the results in
this study (Table 5.1). The 50% anthesis for Monterey, Nudosa, Sicilian Indian fig, Van.
As and Zastron started later than Algerian, Gymno Carpo, Roedtan, Tormentosa and
69
X28. The 50% anthesis for Algerian, Gymno Carpo, (week 3 in October) reported by
Oelofse (2002) occurred a week earlier than what was reported in this study for the same
cultivars. The discrepancies on both budbreak and 50% anthesis between the results of
Oelofse (2002) and that of the present study for different cultivars could be attributed to
the late frost, which befell the latter (4th October 2002) and preeeeding climatic
conditions.
Table 5.1 Basic phenology stages of different cactus pear cultivars for two-year-old
plants.
Bud break Cultivar 50% Anthesis
Week 2 in September Gymno Carpo Week 4 Oct. - Week 3 Nov.
Week 2 in September Monterey Week 3 Nov.
Week 2 in September Morada Week 3 Nov.
Week 2 in September Nudosa Week 3 Nov.
Week 2 in September Roedtan Week 4 Oct. - Week 3 Nov
Week 2 in September Sicilian Indian fig Week 3 Nov.
Week 2 in September Tormentosa Week 4 Oct. - Week 3 Nov
Week 2 in September Van As Week 3 Nov.
Week 2 in September X28 Week 4 Oct. - Week 3 Nov
Week 2 in September Zastron Week 3 Nov.
Week 2 in September Algerian Week 4 Oct. - Week 3 Nov.
5.2.2 Number of fruits
The average number of fruits per plant for each treatment and average number of fruits
per plant for each cultivar are presented in Figures 5.1 and 5.2. The P-values and least
significant differences (LSD) for the different treatments and cultivars (P~0.05 level of
significance) are presented in Table Al. The number of fruits per treatment differed
significantly (P<0.05) from each other. The scozzolatura treatment recorded only few
fruits per plant (P< 0.05) compared to fodder and fruit treatments (Fig. 5.1). The number
of fruits per plant (0.8) under scozzolatura was largely (80%) the contribution of Sicilian
70
Indian fig. The remaining 20% of the total number of fruits per plant under scozzolatura
were the contribution of Algerian and Nudosa. Number of fruits produced per plant under
Sozzolatura was zero for other cultivars. The total number of fruits per plant under
scozzolatura was only one. Such differences between treatments (Fig. 5.1) were not
expected because all the treatments were managed in the same way in this study e.g.
removal of the buds and pruning.
..'-.t.: 0.800
~
Co
"cu-
~ 0.400
-e:::I
~ 0.000 _ptEllilL __ 1i1liliillill4Miill
LL
Treatment
Figure 5.1 Number offruits (plant") for each treatment determined in two-year-old
plants (LSD 0.05 = 0.1408)
A significantly higher (P < 0.05) number of fruits per plant was recorded for Morado and
Roedtan than for all other cultivars while the lowest number of fruits was recorded for
Zastron, Monterey and Nudosa (Fig. 5:2). Most research work on cactus pear does not
include this parameter and therefore there is not much information with which to
compare the recorded findings in this present study. The low number of fruits obtained in
this study for the different cultivars could be attributed to the age of the plant (2 years)
and late frost (4th October 2002). A sudden drop in temperature to below freezing point
(refer to 5.2.7) that does not allow the young plants to acclimatise for successive nights,
could have been too much for many developing buds to survive. If reproductive buds are
71
reduced in number, fruit production will decrease. According to Gregory et al. (1993), a
sudden drop in temperature (28°C to -12°C) does not allow the plants to acclimatise and
express cold tolerance. A shortage in nutrients could also be associated with the low
number of fruits obtained in this study. Fertiliser was applied only at planting during the
study because topdressing could not be carried out due to the long spell of drought
conditions.
Nobel (1988) reported that the number of fruits produced per cladode depends on the dry
weight accumulation in the cladodes, which in turn depends on the net CO2 uptake. For 0.
ficus-indica, cladodes with a higher than average dry weight tend to produce more fruits
(Garcia de Gartázar and Nobel 1992). However in this study the cladode dry mass
percentage for both treatments and cultivars were not significantly different (Fig. 4.10).
';"
ë 1.200
-cvQ.~ 0.800
.~.::.J.....
o~ 0.400
Q)
.c
E
::J 0.000
2:
Cultivar
Figure 5.2 Number of fruits (plant" for each cultivar determined from two-year-old
Plants (LSD 0.05= 0.2981)
Zastron, Tormentosa, Algerian and Gymno Carpo were cactus pear cultivars that suffered
relatively more frost damage than other cultivars during the winter of 2002 (Figure 4. 14).
72
The damage by frost could have played a role in the low number of fruits produced by
these concerned cultivars (Figure 5.2). Even though Monterey and X28 suffered
relatively lower average frost damage during winter 2002 (Figure 4.14), they attained
fewer numbers of fruits (Figure 5.2). It is not surprising that Roedtan and Morado
attained the highest (P< 0.05) average number of fruits because these cultivars were not
damaged as much as Zastron, Algerian, Tormentosa, Gymno Carpo and Van As by frost
in winter 2002. Nudosa, which suffered frost damage equal to Morado, produced the
lowest number of fruit (which was only more than Monterey's).
Some cultivars come into bearing more than others. One should therefore, not laytoo
much stress on the bearing of very young plants. Yield potential can change with time
(Brutsch 1979). In this study, it was impossible to evaluate the number of fruits per plant
for every cultivar during the first and third season. In the first season the developing
plants were not allowed to produce fruits while in the third season the plants were killed
by frost, leaving only the mother cladode.
5.2.3 Fruit mass
Evaluation of this parameter was only possible on two-year-old plants as discussed
previously. Figures 5.3 and 5.4 illustrate the fruit mass per treatment and per cultivar
respectively. The average fruit mass differed significantly between treatments.
Scozzolatura treatment recorded significantly (P<0.05) lower fruit mass compared to the
other treatments. Under the fodder treatment, Gymno Carpo and Sicilian Indian fig
recorded more fruit mass. Under skozzolatura treatment Morado and X28 recorded the
lowest (P<0.05) fruit mass. The differences illustrated in Figure 5.3 between treatments
are hard to explain because the three treatments were managed in the same way. Such a
difference could only be expected at a later stage when management changes as required
for each treatment. The final fruit mass depends on the cultivar, seed number, fruit load
and horticultural management such as thinning and irrigation (Barbera et al. 1997,
Oelofse 2002). One-year-old fruiting cladodes are the main source of photosythetates for
fruit growth in cactus pear (Barbera et al. 1997, Oelofse 2002). The ability of the cladode
73
to support fruit growth depends on the previous year's fruit load and its light interception
during the season (Barbera ef al. 1997, Oelofse 2002). Higher mean fruit mass (P<0.05)
for fodder over fruit and scozzolatura obtained with Gymno Carpo is questionable,
because the plants were not allowed to bear fruit in the previous year in this study.
The highest fruit mass of 60.35 per plant recorded for Algerian, was significantly higher
(P<0.05) than fruit mass obtained for Gymno Carpo, Zastron, Sicilian Indian fig and
Monterey. Tormentosa also recorded higher (P<0.05) fruit mass per plant (54.23g) than
Monterey, Sicilian Indian fig and Zastron. X28 also registered a relatively high average
fruit mass per plant. In view of the findings by Brutsch (1979) Piemienta - Barrios and
Mufios (1995) Van der Merwe ef al. (1997) and Oelefse (2002) who recorded 88 -109g,
84 -175g, 113 - 163g and 161.88 - 185.08g fruit mass respectively from mature cactus
pear plants, the values reported in this study are very low. These discrepancies could be
attributed to the age of the plants and shortage of nutrients. The plants were fertilised
only once during establishment. Because of a long spell of drought (refer to 4.2.7) it was
not possible to topdress the plants during the study. Also in view of the minimum criteria
for (140. Og) cactus pear varieties evaluated for fruit production (Potgieter et al. 1989), the
reported results on fruit mass in this study were very low.
According to Brutsch (1979), Algerian, which was dominant in this study in terms of
average fruit mass per plant compared to other cultivars, produced the lowest values
(88g) in their trials when compared to Morado (97g) and Gymno Carpo (102g).
Piemienta-Barrios and Muftos (1995) recorded a greater average fruit mass per plant for
Morado (114g) and Nudosa (175g) than Algerian (110g). This data is contrary to the
findings obtained in this study. Oelofse (2002) recorded lower fruit mass per plant for
Algerian (161.88g) compared to that of Nudosa (236g), Gymno Carpo (171g) and
Roedtan (171. 74g). The results of Oelofse (2002) thus do not agree with those of this
study. The results obtained in this study are however in agreement with those reported by
Oelofse (2002) on the lowest fruit mass per plant obtained for Zastron. Fruit mass also
depend on whether or not there was fruit thining or not. There was no fruit thining in the
trial reported by Brutsch (1979).
74
..'-. 60.000e-
ctI
Q.
-CJ) 30.000lIJ
lIJ
ctI
:2; 0.000
«O~Oe<"
Treatment
Figure 5.3 Average fruit mass for each (g plant") treatment determined from two-year-
old plants (LSD 0.05 = 21).
Most of the research work with which the findings of this study were compared,
considered mature plants and such data on the performance of the young plant is lacking. .
Low average fruit mass from young cactus plants obtained in this study should not
discourage further trials. More research work should be carried out regarding the
performance of young cactus pear plants. Even though the results reported in the present
study were disappointing, when compared with records presented by Brutsch (1979),
Pimienta-Barrios and Mufioz (1995), Van der Merwe et al. (1997) and Oelofse (2002) for
older plants, there are some good indications that cultivars such as Algerian, Morado,
Tormentosa, Van As and X28 can produce desirable fruits in terms of the fruit mass per
plant However, the plants were too young to make meaningful predictions.
75
"-;" 90.00 -r-------------------------,
~c::
Qca. 60.00 -1-.=-----------------------1
=C-') 30.00
fn
fn
:cEa 0.00 -f--"_'_"""""'-,-
Cultivar
Figure 5.4 Average fruit mass (kg plant") for each cultivar determined from the two-
year-old plants (LSD 0.05 = 27.2822).
5.2.4 Fruit yield
Figures 5.5 and 5.6 illustrate the fruit yield per treatment and for the Il cactus pear
cultivars subjected to fodder, fruit and scozzolatura treatments. The difference between
treatments in terms of fruit yield was significant (P<0.05). The differences would be
expected later when management starts to differ depending on the requirements of a
particular treatment. Morado contributed 58% percent of the total fruit yield recorded for
fodder treatment while Tormentosa contributed 10%. The remaining 32% were shared by
other cultivars. The total yield (76.8kg) obtained by the fruit treatment in this study was
largely the contribution ofRoedtan (30%) and Gymno Carpo (35%). The remaining 35%
were shared by other cultivars. The total fruit yield obtained by the Scozzolatura
treatment was due to just three cultivars namely: Algerian (7%), Nudosa (16%) and
Sicilian Indian fig (77%). The other nine cultivars studied did not produce fruits under
Scozzolatura.
76
60.0000
30.0000
0.0000
Figure 5.5 Fruit yield (kg ha") for each treatment determined from two-year-old plants
(LSD 0.05 = 20.52).
"7-ca 90.0000
~ 60.0000
~
- 30.0000
"C
:Q;) 0.0000
Cultivar
Figure 5.6 Fruit yield (kg ha -I) per cultivar determined from two year old plants (LSD
0.05 = 28.20)
77
The values obtained from this study were low and not comparable with the fruit yield of
1.3,3.1,6.3, 15.6 and 7.5 t ha" reported for 2,3,4-15, 16-20 and 21-35 year old plants
respectively (SAG 1976). These yields were moreover made possible by some irrigation
and use of 12-kg goat manure per individual plant. Based on the minimum criteria
(Potgieter et al. 1979) for cactus pear varieties evaluated for fruit production (1, 2.5, 4, 7,
10, 15 and 20 t ha-I for 2, 3, 4, 5, 6, 7 and 8 year old plants respectively) the values
obtained in the present study were disappointing. Van der Merwe et al. and Oelofse
(2002) reported higher values of 4.3 - 13.2 and 4.97 -30.67 t ha -I respectively for mature
plants, than those reported in this present study. Such yields were, however, obtained
from mature cactus pear plants. The discrepancies could be due to lack of irrigation, use
of manure, age of plants, shortage of nutrients and very low minimum temperatures for
successive nights, which injured c1adodes during winter (as discussed previously). It was
only possible during the study to monitor this parameter in the second season (2002/2003
growing season). No evaluation took place in the first (2001/2002) and third (2003/2004)
growing seasons as discussed earlier.
5.2.5 Total Soluble Solids (TSS)
Figure 5.7 illustrates TSS values for the eleven cactus pear cultivars. It was only possible
to monitor these parameters in the second season of the study (2002/2003). In the first
growing season (2001/2002) the plants were not allowed to produce fruits, while in the
third growing season (2003/2004) all the plants except some mother c1adodes were killed
by frost. In this study, Van As (15 Brix% TSS) and Tormentosa (15Brix% TSS) recorded
relatively higher TSS values than other cultivars. However, owever, this was only
significant (P> 0.05) when compared to Monterey (9 Brix% TSS). Monterey recorded the
lowest TSS values. According to Potgieter and Mkhari (1989) the minimum criteria for
cactus pear varieties evaluated for fruit production potential should be more than 13
Brix% TSS. Based on this criterion, cultivars such as Gymno Carpo, Morado, Sicilian
Indian fig, Tormentosa, Van As and X28 complied with the recommendations while the
rest failed. Total Soluble Solids values for Algerian, Nudosa and Morado (Pimienta-
Barrios and Munuz-Urias 1995) are in agreement with the findings recorded in this study.
78
- 20.00:IJ(.t: 15.00
Dl
-~ 10.00Clen 5.00
CJ)
._; 0.00
Cultivar
Figure 5.7 Total Soluble Solids % for the different cultivars (LSD 0.05 = 4.7454)
The Total Soluble Solids for Gymno Carpo was found to be higher than 13% Brix TSS in
this study but less according to the results obtained by Pimienta-Barrios and Mufiuz-Urias
(1995) and Oelofse (2002). Oelofse (2002) recorded TSS values higher than l3% Brix for
Zastron, Algerian and Roedtan while they reflected lower values in this study. Since the
decision of when to collect fruits for TSS evaluation is subjective and the ripeness of the
fruits is not uniform, this might explain the difference in TSS values reported above. The
Total Soluble Solids is one of the parameters characterising fruit quality. It is generally
recognised that during the final weeks of flesh development, optimum TSS values at
harvest should be 13-15% (Barbera et al. 1992b, Kuti 1992).
5.2.6 Pulp colour, peelability index and harvest period
Table 5.2 presents pulp colour, peelability index (ease to peel the fruit) and harvest period
of the 11 cactus pear cultivars under study.
79
Table 5.2 Pulp colour, peelability index, main harvest period and harvesting date for
young cactus plants of different cultivars different cultivars.
Cultivar Colour Peelabity Main harvesting Harvesting date
index period
Gymno Carpo Orange Good End Jan. - begin 28/01/03
Mar.
Monterey Dark red Poor End Jan 28/01/03
Morado Light green Good End Jan. - begin Mar 28/01/03
Nudosa Red Good End Jan. - begin Mar 28/01/03
Roedtan Orange Good End Jan. - begin Mar 28/01/03
Sicilian fig Red Good End Jan 28/01/03
Tormentosa Orange Good End Jan. - begin Mar 28/01/03
Van As Light-green Good End Jan. - begin Mar 613/03
X28 Orange Good End Jan. - begin Mar 28/01/03
Zastron Light-green/white Good Begin Mar. 6/3/03
Algerian Red Good End Jan. 28/01/03
It was only possible during the study to monitor these parameters in the second season of
the study (2002/2003). The results (pulp colour) mostly match the descriptions reported
by Oelofse (2002) and that reported by Brutsch (1994, 1997). Dark pink pulp colour of
Algerian (Oelofse 2002, Pimienta-Barrios 1995) does however differ from the results
presented in Table 5.2. Yellow fruit colour for Gymno-Carpo (Brutsch 1994) differs
slightly from the results in Table 5.2. Figure 5.8 depicts different colours of fruits from
five cactus pear cultivars. All cultivars except Monterey, whose peelability was described
as poor (Table 5.2), were easy to peel according to the present study.
80
AIg<zrian
X28
Morado
Figure 5.8 The different colours of fruits of some cactus pear cultivars
The main harvesting period corresponds with that reported in previous works (Brutsch
1994, 1997: Pimienta-Barrios and Mufioz-Urias 1995, Oelofse 2002). However, Oelofse
(2002) whose description of a harvesting period for Zastron and Roedtan was the third
week of January differed from the results presented in Table 5.2. The most appreciated
fruits on the international market are yellow-orange (peel and flesh). Red-purple fruits,
81
like Algerian are also appreciated. Green-clear or white cultivars as well as pink-orange
ones are relevant only in regional markets and present major problems in handling and
storage (lngles Barbera 1992). The different colours of fruits of some cactus pear
cultivars are shown in Figure 5.8.
5.2.7 Peel-thickness
Figures 5.9 and 5.10 illustrate peel-thickness per treatment and per cultivar for the Il
cactus pear cultivars: It was only possible during the study to monitor these parameters in
the second season of the study (2002/2003). Peel-thickness was significantly (P<0.05)
different between treatments. The fodder treatment attained higher peel thickness
(P<0.05) than the other treatments. The Skozzolatura treatment recorded the lowest
(P<0.05) peel-thickness. The recorded difference between treatments in terms of peel-
thickness is questionable because the young cactus pear plants in this study received the
same attention. Peel-thickness differences were significant (P<0.05) between some
cultivars. Peel-thickness for Algerian and Nudosa was greaterr than that recorded for
Gymno Carpo, Monterey, Roedtan and Sicilian fig. The thinner peel recorded for
Monterey was significant when compared to that of all other cultivars except Roedtan
and Zastron.
E
-E 4
Treatment
Figure 5.9 Peel-thickness for each treatment (LSD 0.05 = 1.4688).
82
All the cultivars evaluated in this present study conform to the requirements «6mm) for
fruit production according to the recommendations of Potgieter and Mkhari (2002) in
terms of peel-thickness. The results presented in this present study (Figure. 5.10) are to
some extenT different from 6.60, 6.41, 5.24, 2.89, 6.20 and 4.94 for Nudosa, Gymno
Carpo, Morado, Zastron, Algerian, and Roedtan respectively reported by Oelofse (2002).
Oelofse (2002) reported the lowest peel-thickness value for Roedtan compared to other
cultivars. In the present study Roedtan, which produced lower peel-thickness, than all
cultivars except Monterey (Figure 5.10) supported the findings of Oelofse (2002).
-
-EEtb
tb
Cl)
.r~u_:::
-J..:.:.ICl)
Cl)
c,
Figure 5.10 Peel-thickness (mm) for each cultivar determined from two-year-old plants
(LSD 0.05 = 1.534)
5.2.8 Seed numbers and mass of cactus pear seeds
Table 5.3 presents average seed number and mass of seeds from the Il cactus pear
cultivars in the second season (2002/2003). Some cultivars differed in terms of number of
fully developed seeds and mass of both fully developed and aborted seed. The number of
aborted seeds did not differ significantly (P>0.05) between different cultivars. The mean
mass of mature seeds for Van As was higher (P<0.05) than those recorded for the other
83
cultivars. Roedtan produced more (P<0.05) aborted seed than other cultivars. The lowest
mass of aborted seeds recorded for Morado was not significantly (P<0.05) different from
that recorded for other cultivars excluding Roedtan. The findings provided in this present
study could not be readily compared with results recorded by other researchers because
most of the research did not include this parameter.
Table 5.3 Seed numbers and mass (g) of seeds for each cultivar from two-year-old plants.
Cultivar Mean number of seeds Mean mass of seeds (g)
(fruit -1)
Mature seeds Aborted seeds Mature seeds Aborted seeds
Algerian 169 76 2.50 0.39
Monterey 200 72 2.50 0.10
Morado 127 17 1.60 0.33
Nudosa 175 66 2.30 0.77
Roedtan 106 45 1.80 0.44
Sicilian Indian fig 166 68 2.47 0.28
Tormentosa 88 40 1.50 0.31
Van As 208 67 3.17 G.41
X28 142 69 2.03 0.37
Zastron 176 61 2.80 0.28
Gymno Carpo 153 35. 2.90 0.27
LSD 0.05 55.208 43.695 0.771 0.286
One of the major constraints limiting the consumption of cactus pear is the presence of
thick, hard seeds in the flesh. Empty aborted, caused by early failure of embryo growth,
are common In cactus pears and allow flesh development (Pimienta-Barrios and
Engleman 1985). The ratio between aborted and normal seeds is one of the most
important parameters that define fruit quality (Barbera et al. 1992c). Lack of data in
South Africa (Pimienta-Barrios 1990: Barbera et al. 1992a) regarding this parameter
makes it impossible to compare findings reported in this present study. Seed size can vary
by cultivar (Barbera et al. 1992a; 1992c) and by species (Nerd et al. 1990). More
research work is needed to reduce seed number, seed size and increase the percentage of
empty seeds.
84
5.2.9 Conclusions
This study has demonstrated that a prolonged winter or late frost could delay the
phenological stages in some cultivars of young cactus pear plants. In this study, budbreak
and 50% anthesis were delayed by at least a week compared to the findings of Oelofse
(2002). If some reproductive buds are damaged by late frost, the number of fruits, and
fruit yields produced by individual plants could be affected. The degree of frost damage
to young cactus pear plants may lead to fewer fruit bearing cladodes, fewer fruits
produced (plant -1), and low fruit yield (plant -1) or even death.
Based on minimum standards «6mm) for fruit production according to Potgieter and
Mkhari (2002) in terms of peel-thickness, all the cultivars studied possessed desirable
traits for fruit production. In the Minimum Descriptor List for Opuntia spp. (http:
//www.unifi.it/ueresgen29/netddase/s5/dls5.htm). only Tormentosa qualified to be
categorised as cultivar producing a very few seed « 100) while the other cultivars are
considered to produce few seed (lOl - 200). Van As falls under a medium (201 - 300)
seed-producing cactus pear cultivar. Table 5.4 presents the findings about the cultivars
individual performance on different reproductive characteristics.
The incidences of frost damage experienced during the study call for further research
work to determine the minimum range of temperatures that could delay phenological
stages in cactus pear. Also careful choice of site for the establishment of cactus pear
plantations (not prone to severe frost) is necessary to avoid possible frost damage to
developing buds. It needs to be determined whether fruits from young cactus plants (l-3
years) differ from the fruits obtained from mature plants in terms of peel thickness. This
is necessary because the peel thickness recorded by Oelofse (2002) was higher compared
to the data provided in this study.
85
Table 5.4 Performance summary of the different cactus pear cultivars
Cultivar Number of Fruit mass Fruit yield Fruit yield Peel
fruits plant -1 ha -1 thickness
Algerian + + ± ± +
Gymno Carpo + ± ± ± +++
Monterey - - - - ++++
Morado +++ ± ++ ++ ++
Nudosa - ± - - +
Roedtan ++ ± + + ++++
Sicilian fig ± - - - ++
Tormentosa ± + ± ± ++
Van As + ± ± ± ++
X28 ± + ± ± ++
Zastron - - - - ++++
Key:
Exellent ++++ Good ++ Poor ±
Very good +++ Satisfactory + Very poor
86
Chapter 6
General discussions and conclusions
Cactus pear is a multipurpose crop, which can be of great value in both developed and
developing countries, because of its ability to utilise the full potential of arid areas The
full potential of cactus pear has not however, been realized in southern Africa. Spineless
cactus pear in South Africa is increasingly commercialised and there is a need to establish
a database to assist the South African farmers in the selection of cultivars for production
(Oelofse 2002). Cactus pear can be produced with great success on land presently
deemed marginal for other crops (e.g. wheat, maize and sorghum). In light of the known
variability of the rainfall precipitation regimes, it is hoped that cactus pears can also be
successfully included into many rangeland management schemes in Southern Africa.
There are vast areas of Sub-Saharan Africa where the cactus pear could be grown with
ease and to good advantage, particularly when one bears in mind the all-too-frequent
droughts.
This study clearly indicated that young (1-3 year's) cactus pear plants grow more in
height than width. The cultivars that grow more in height than others also tend to achieve
more growth in width with the exception of Zastron whose growth in width does not tally
with growth in height. Prolonged minimum temperatures of-5 DC on successive nights
can affect growth and therefore, height in young cactus plants. Frost damage leads to a
decrease in both width and height
This study has demonstrated that more growth in height and width in young cactus plants
is essential for the production of a larger number of cladodes on a plant before pruning
(and therefore, number of cladodes removed by pruning), cladode yield and fruit yield.
These results are of the few available for young cactus plants, because the available
literature has concentrated on the fodder and fruit productions of full-grown plantations.
Although this research project was planned for over a few years, the plants were
unfortunately killed by frost after only three years. Therefore, there is no indication of
87
difference between the different treatments (fodder, fruit and skozzolatura) that could be
quantified. Studies such as this one need to be carried out in the future to get a clearer
picture of the production potential of the different cultivars under different management
practices. Because data was collected over only a two to three-year period, limited useful
information on fodder and fruit productivity for different cultivars was obtained. All the
cultivars studied showed the ability to produce more fodder than fruits. The study has
shown that Roedtan and Morado are outstanding in terms of fodder and fruit production.
Other promising cultivars for both fodder and fruit production were Algerian, Gymno
Carpo, Nudosa and Van As. Monterey and Zastron did not posses desirable traits for fruit
production. The individual performance of cultivars based on fodder and fruit production
is summarised in Table 6.1.
Table 6.1 Performance summary of different cultivars in terms of fodder and fruit
production based on two to three-year-old plants.
Cultivars Fodder Fruit
Algerian ++ +
Gymno Carpo ++ +
Monterey + -
Morado +++ ++
Nudosa ++ +
Roedtan ++++ ++
Sicilian Indian fig + +
Tormentosa + +
Van As ++ +
X28 + +
Zastron ++ -
Key:
Excellent ++++ Good ++ Poor ±
Very good +++ Satisfactory + Very poor
88
In order to be successful in cactus pear production for fodder and fruits, it is very
important to select areas that are not prone to severe frost. There is a need to topdress the
plants with fertiliser every year if possible to improve production. Unfortunately the
plants were not fertilised in either the second or the third season of the study. According
to most researchers the cactus pear reacts possitively to fertilisers. Shortage of nutrients
may affect both fodder and fruit production negatively. Weeding of the cactus pear field
is very important to minimise competition for nutrients and moisture, during dry period.
Mechanical weeding in cactus pear plantations, if done close to the plants, may damage
the roots that spread near the surface of the soil. The best way to control weeds on a
cactus pear field is therefore chemically. Further research work is required to select
adapted cactus pear cultivars with high fodder and fruit production characteristics.
The commercial cultivation of spineless cactus for its fruit IS a relatively recent
undertaking in South Africa but has been shown to possess huge export potential
(Oelofse 2002). As there has been an increasing interest in cactus pear for both fodder
and fruit production over the last few years, more research needs to be carried out on the
evaluation of different cultivars under different environmental conditions. Cactus pear
can be beneficial to both developed and under-developed countries. According to the
minimum descriptor list for Opuntia species for fruit production, only Tormentosa
qualifies to be categorised as a cultivar producing very few seed « 100 per fruit), while
most the other cultivars produce few seed (101 - 200 per fruit). Van As produces a
medium number of seeds (201 - 300)
The severe frost damage in 2003 greatly reduced the value of the trial since a second year
of data was not possible and it is not possible to obtain reliable data from a single harvest
season, particularly if it is the first (two-year-old plants). Irregular bearing is common in
cactus pear plantings and important differences exist even between plants of the same
cultivar in a particular season. Therefore, the limitations of this study must be borne in
mind and meaningful comparisons with other studies are difficult.
89
Summary
The search for appropriate plant species able to produce with sustainably in arid and
semi-arid areas, has been a concern for some farmers living in such harsh environments.
Unfortunately there is a lack of information concerning the adaptability of different
cactus pear cultivers under a range of environmental conditions. This includes the
cultivation for both fodder and fruit production. Cactus pear could be introduced with
great success on land presently deemed marginal for other crops. A study was therefore
conducted to evaluate the production potential of ten cultivars of the green pad cactus
pear species (Opuntia ficus-indicaï and one blue pad cultivar of 0. robusta over three
growing seasons (2001/02 to 2003/04). The cultivars of 0. ficus-indica included
Algerian, Gymno Carpo, Morado, Nudosa, Roedtan, Sicilian Indian fig, Tormentosa, Van
As, X28 and Zastron. The species 0. robusta was represented by the cultivar Monterey.
The experimental layout was a randomised block design with three treatments (fodder,
fruit and scozzolatura), consisting of 11 cultivars replicated twice on 66 plots. Each plot
consisted of 20 plants, of which 10 were used as data plants, planted in two rows. During
the study vegetative, reproductive and laboratory measurements were evaluated for the
different treatments and cultivars.
It was evident from this study that young cactus pear plants could be killed by a
combination of frequent successive nights of temperatures below the freezing point (as
low as -9°C) and water stress. Shortage of soil nutrients could also influence both fruit
and fodder production in young cactus plants. Mechanical weeding near the cactus plants
could damage the shallow and widespread roots thus reducing the ability of plants to cope
with harsh drought. Therefore, chemical control of weeds is encouraged.
This limited study has revealed that Roedtan is the best cultivar for both fodder and fruit
production while Morado is also ideal for production of both fodder and fruit. Other
promising cultivars (although not as outstanding) for fodder production are Algerian,
Gymno Carpo, Nudosa, Van As and Zastron. The same cultivars, except Zastron, can
produce promising results in fruit production. Monterey, Sicilian Indian fig, Tormentosa
90
and X28 can produce satisfactory results in terms of fodder production. The same
cultivars except Monterey can produce satisfactory results in terms of fruit production.
The study has proved that Zastron and Monterey should be discouraged for fruit
production. However, more in-depth research should be carried out to provide more
information about the cultivars in the different arid environmental conditions of southern
Africa.
In the minimum descriptor list for Opuntia species for fruit production, only Tormentosa
qualifies to be categorised as having very few seeds « 100), while most of the other
cultivars have few seeds (101 - 200). The study has demonstrated that all other cultivars
except Monterey are easy to peel. It needs to be established by research if there is a
difference between young and mature cactus pear cultivars in terms of number of seeds
produced per fruit. The limited information obtained from this study could benefit both
commercial and subsistence farming communities living in drought threatened areas.
91
OPSOMMING
Die soeke na toepaslike plant spesies wat in staat is om suksesvol te groei en volhoubaar
te produseer onder sulke strawwe omgewingstoestande, wat ariede en semi-ariede
gebiede soms ondervind, is 'n groot probleem vir sekere boere. Die turksvyplant kan wel
met groot sukses in hierdie sogenaamde marginale gebiede verbou word. Ongelukkig
bestaan daar nog 'n groot leemte rondom die aanpasbaarheid van verskillende
turksvykultivars vir verbouing onder verskillende omgewingstoestande. Dit sluit die
verbouing vir beide voer- en vrugproduksie in. 'n Studie is gevolglik uitgevoer ten einde
die produksiepotensiaal van tien kultivars van die groenblad turksvy spesie Opuntia
ficus-indica en een bloublad kultivar van die spesie 0. robusta, oor drie groeiseisoene
(2000/01 tot 2002/03) te evalueer. Die kultivars vir 0. ficus-indica het ingesluit
Algerian, Gymno Carpo, Morado, Nudosa, Roedtan, Sicilian Indian fig, Tormentosa, Van
As, X28 en Zastron. Hierteenoor is slegs die kultivar Monterey vir die spesie 0. robusta
ondersoek. Die proefuitleg was 'n ewekansige blok ontwerp met drie behandelings (voer,
vrugte en skozzolatura), bestaande uit Il kultivars wat twee keer herhaal is op 66 persele.
Elke perseel het bestaan uit 20 plante, geplant in twee rye, waarvan 10 ewekansig gekies
is as data plante. Tydens die studie IS van vegetatiewe, reproduktiewe en
laboratoriumrnetings vir die evaluering van die verskillende behandelings en kultivars
gebruik gemaak.
Hierdie beperkte studie het getoon dat jong turksvyplante kan afsterf as gevolg van 'n
kombinasie van opeenvolgende lae nagtemperature van laer as vriespunt (so laag as -
0.9°C) asook waterstremming. 'n Tekort aan grondvoedingstowwe kan beide voer- en
vrugproduksie van jong turksvyplante beïnvloed. Meganiese bewerking naby die
turksvyplant mag die oppervlakkige en wydverspreide wortelstelsel beskadig en
gevolglik die vermoë om droogtetoestande te weerstaan, verlaag. Daarom word
chemiese onkruidbeheer eerder aanbeveel.
92
Die studie het bewys dat Roedtan die beste kultivar vir beide voer- en vrugproduksie is,
terwyl Morado ook ideaal vir beide voer- en vrugproduksie is, alhoewel nie so uitstaande.
Ander belowende kultivars vir voerproduksie is Algerian, Gymno Carpo, Nudosa, Van
As en Zastron. Dieselfde kultivars, met die uitsondering van Zastron, kan ook as redelik
belowende vrugproduksie kultivars beskou word. Monterey, Sicilian Indian fig.,
Tormentosa en X28 het redelik gevaar in terme van voerproduksie. Dieselfde kultivars
met die uitsondering van Monterey kan ook redelik vaar in terme van vrugproduksie. Die
studie het getoon dat die verbouing van Zastron en Monterey ontmoedig moet word vir
vrugproduksie. Nog meer indiepte studies behoort in die toekoms uitgevoer te word
rondom kultivar evaluasie onder verskillende omgewingstoestande van suidelike Afrika.
In die lig van die minimum vereistes gestel vir Opuntia spesies se vrugte, was dit slegs
Tormentosa wat gekwalifiseer het as 'n kultivar met min «100) sade in die vrugte
geproduseer. Hierteenoor het al die ander kultivars misluk in terme van minimum sade
per vrug (101-200) geproduseer. Die studie het ook getoon dat al die kultivars met die
uitsondering van Monterey se vrugte baie maklik afskil. Die verskille in sade per vrug
tussen jong en volwasse turksvyplante, vir verskillende kultivars in terme van aantal
regverdig beslis verdere indiepte navorsing. Die resultate met hierdie studie verkry, kan
van groot waarde wees vir beide ontwikkelde en ontwikkelende boerdery gemeenskappe.
93
References
Abramo P 1935. Fico d'india nel alimentazione del besttiame. Revista di Zootechnia, 13
Firenze. 14 pp.
Archibald E E A 1935. The development ovule and seed of jointed cactus (Opuntia
ficus-indicaï. South African Journal of Science VXXXVI: 195-211 .
Azocar P 1992. Biomasa y biotecnologia. Uso de cladodios de tuna tOpuntia ficus-
indicaj en la alimentación de cabras. Aetas II Congreso Internacional de la Tuna y
cochinilla. Facultad de Ciencias Agrarias y Forestales, Universidad de Chile.
Santiago, 22 al25 de septiembre de 1992. 119-125.
Azocar Pand Rojo, H 1991. Uso de cladodios de tuna (Opuntia ficus-indicay como
suplemento forrajero estival de cabras en lactacia en reemplazo de heno de alfalfa.
Avances en Producción Animal 16 (1-2): 173 - 182.
Azócar PRojo, H Mira, J and Manterola H 1996. Inclusiónde nummmularia (Atriplex
nummularia Lind!.) y cladodios de tuna (Opuntia ficus-indicaj en la dieta de
cabras criollas en reemplazo de heno de alfalfa. 1. Efecto en el consumo, peso
vivo y producción de leche. Avances en Producción Animal 21 (1-2): 43-50.
Barbera G 1984. Ricerche sull'irrigazione del fico d'india. Frutticoltura 46: 49-55.
Barbera G, Carimi F and Inglese P 1991. The flowering of prickly pear (Opuntiaficus-
indicay. Influence of removal time and cladode load on yield and fruit ripening.
Adv. Hort. Sci. 5: 77-80pp. Barbera G and Inglese P 1993. (eds.) La coltura del
fico d'india. Calderini Edagricole. Bolonga, Itally. 189 pp.
94
Barbera G, Carimi F and Inglese P 1992a. Past and present role of the Indian fig
prickly pear (Opuntiaficus-indica (L) Mill) Cactaceae in the agriculture of Sicily.
Economic Botany 48 (1): 10-20.
Barbera G, Carimi F, Inglese Pand Panno M 1992b. Physical, morphological and
chemical changes during fruit development and ripenig in three cultivars of
prickly pear, Opuntia ficus-indica (L) Mill. Journal of Horticultural Sciences 67
(3): 307-312.
Barbera G, Carimi F, Inglese P and La Mantia T 1992c. Seeed content and fruit
characteristics in the cactus pear (Opuntiaficus-indica). II Congresso
Internacional de Tuna y Cochnilla, 232 - 25 September, Santiago (Chile), 4.
Barbera G and La Mantia T 1992. Seed content and fruit characteristics in cactus pear
(Opuntia ficus-indicay. Congreso Internacional de Tuna y Cochinilla, 22-25
September, Santago (Chile), 4 pp.
Barbera G, La Mantia T, Portolano Sand Inglese P 1993. The effect of thinning on
growth and ultimate size of cactus pear (Opuntia ficus-indicay fruits. ISHS
Congress on fruit quality, Crete, 10-12 September.
Barbera G, Inglese P 1993. La coltura del Ficodindia. Calderimi Edagricole, Bologna,
Italy, 189 pp.
Barbera G, Inglese Pand Pimienta-Barrios E 1994. Agroecology, cultivation and use
of cactus pear (Opuntia spp.). FAO, Rome.
Barbera G 1995. History, economic and agro-ecological importance. In: Agro-ecology,
cultivation and uses of cactus pear Barbera G, Inglese Pand Pimienta-Barrios E
(eds.) FAO Production and Protection Paper 132: 1-12.
95
Ben Salem H, Nefzaoui A and Abdouli, H 1994. Palatability of shrubs and fodder trees
measured on sheep and dromedaries: Methodology approach. Animal Feed
Science and Technology 46: 143-153.
Ben Salem H, Nefzaoui A, Abdouli Hand Orskov E R 1996. Effect of increasing
levels of spineless cactus (Opunua ficus indica var. inermis) on intake and
digestion by sheep given straw-based diets. Animal Science 62: 293-299.
Botha J P H 1964. Die Klimaat van Glen. Landbouweerkunde verslag.
Landbounavorsingsinstituut, Glen. Departementele verslag.
Bravo H 1978. Las Cactaceae de Mexico. 2a ed. Vol. 1. Univ. Nac. Mexico D .F.
Brutsch M 0 1979. The Prickly pear (Opuntiaficus-indica ) as a potential fruit crop for
the drier regions of the Ciskei. Crop Production VIII: 131-137.
Brutsch M 0 and Scott M B 1991. Extending the fruiting season of spineless prickly
pear Opuntia ficus-indica Journal of South African Society of Horticultural
Science. 1:73-76.
Brutsch M 0 1992. Crop manipulation in spineless prickly pear (Opuntiaficus-indica)
in South Africa. IICongresso lnternacional de Tuna y Cochnilla, 232 - 25
September, Santiago (Chile), 6.
Brutsch M 0 and Zimmermann H G 1993. The prickly pear (Opuntia ficus-indica
cactaceae) in South Africa: Utilisation of the naturalised weed, and of the
cultivated plants. Economic Botany 47 (2): 154-156.
Brutsch MO 1994. The cactus pear as a fruit crop in the eastern Cape, with special
referenceto cultivar evaluation and crop manipulation. (Progress Report),
Department of Agronomy, University of Fort Hare.
96
Brutsch M 0 1997. Climatic data of selected cactus pear (Opuntiaficus-indica) growing
areas in South Africa. Proceedings of the third International Congress on Cactus
Pear and Cochnnille, South Africa 438: 13 - 20.
Brutsch M 0 2000. A comparartive assessment of the status and utilization of
naturalized Opuntia ficus-indica in the Eastern Cape Province of South Africa and
in Tigray, Ethiopia. Proceedings of the Fourth International Congress on cactus
pear and Cochineal. Tunisia. Acta Horticulturae 51.
Buxbaum F 1950. Morphology of Cacti. Abbey Garden Press. Calif., USA.
Buxbaum F 1955. Morphology of cacti. III. Fruits and seeds. Abbey Garden Press.
Pasadena.
CantweIl (de Trojo) M 1986. Post-harvest aspects of prickly pear fruit and vegetable
cladodes. Perishable Handling (Univ.Calif., Davis) 59:6-9.
CantweIl (de Trojo) M 1991. Quality and postharvest physiology of "Nopalitos" and
"tuna". Second Annual Texas Prickly Pear Conference, Texas Prickly pear
Council, Me AlIen, Texas. pp 50-66.
CantweIl (de Trojo) M 1992. Aspectos de calidad y manejo posteosecha de nopalitos.
In: Salazar S. and López (eds.). Conocimiento y aprovechamiento del nopa1.5to
congreso Nacional y 3er Internacional. Memoria de Resurnenes. UACH.
Chapingo, Mexico. 110 pp.
Castro J Pérez Sand Riquelme E 1977. Evaluation ofthornless prickly pear silage as a
feed stuff for nutrients. Proc. Western Section, American Soc. Animal Sci., 28.
Cordier G 1947. De la composition de quelgues produits fourragers tunisienset de leur
valeur pour l'alimentation du mouton. Ann. Serv. Bot. Agron. Tun. 20: 22-108.
97
Corrales G J 1992. Descripción y análisis de cosecha y manejo en fresco de nopalito
tuna. Salazar Sand López (eds.). Conocimiento y aprovechamiento del nopal.5to
congreso Nacional y 3er Internacional. Memoria de Resurnenes. UACH.
Chapingo, Mexico. 119 pp.
Cottier H 1934. Quelques aliments de disette, leur valeur et leur emploi. La Tunisie
Agricole 37: 127-141.
De Kock G C 1965. The management and utilization of spineless cactus tOpunua
spp. ).Proceedings of the fourth International Grassland Congress, Soa Paula,
Brazil pp 1471-1474.
De Kock G C 1967. Fodder production in semi-arid and areas. Fmg South Africa 59.
De Kock G C 1970. Spineless cacti, the farmers' provision against drought. Leaflet No.
37. Res. Inst. of the Karoo Region, Dept. of Tech. Serv. Govt Printer, Pretoria,
South Africa.
De Kock G C 1974. Turksvy kan doring van 'n inkomste lewer. Landbouweekblad 17,
18-21.
De Kock G C 1980. Drought- resistant fodder shrub crops in South Africa. 399-408. In:
Le Houérou RN (ed.) Browse in Africa. The current State of Knowledge. Paper
presented at the International Symposium on Browse in Africa, Addis Ababa, 8-
12 April 1980, and other submissions. International Livestock Centre for Africa,
Addis Ababa, Ethiopia.
98
De Kock G C 1998. The use of cactus pear (Opuntia spp) as a fodder source in the arid
areas in South Africa. pp 83-95, In: Proc. International Symposium on cactus
pear and "Nopalitos" processing and uses. Universidad de Chile, Santiago, and
International Cooperation and Network on Cactus pear.
Felker P 1995. Forage and fodder production and utilization. pp 144-154 pp. In: Barbera
Glnglese Pand Pimienta-Barrios (eds.) Agroecology, cultivation and uses of
cactus pear. FAO Plant Production and Protection paper, 132.
Felker Pand RusseIl C E 1988. Effect of herbicides and cultivation on the growth of
Opuntia in plantation. Journal of Horticultural Science 63: 149-155 .
Felker P 2001. Utilization of Opuntia for forage in the United States of America. pp 51-
56 pp, In: FAO cactus (Opuntia spp.) as forage, FAO plant production and
protection paper 169, Rome, Italy.
Florez-Valdez C A 1992. Growing, commercializing and marketing cactus leaves in
Mexico. Proc. 3rd Annual Prickly Pear Conference, Texas pp 56-65.
Garcia de Cortázar V and Nobel, P S 1990. Worldwide environmental productivity
indices and yield predictions for a CAM plant, Opuntia ficus-indica, including
effects of doubled CO2 levels. Agricultural and Forest Meteorology 49:261-279.
Garcia de Cortázar Vand and Nobel P S 1991. Prediction and measurement of high
annual productivity for Opuntiaficus-indica. Agricultural and Forest Meteorology
34, 145 - 162.
Gibson A and Nobel P 1986. The cactus primer. Harvard Univ. Press, Cambridge.
Gonzales C L 1989. Potential of fertilization to improve nutritive value of prickly pear
cactus. Journal of Arid Envionvironments 16: 87-94.
99
Granata G and Varvaro L 1990. Bacterial spots and necrosis caused by yeast in prickly
pear in Sicily. Proc. s" Congress. Midit. Phytopathol. Agadir, Morocco. 467-468.
Gregory R A, Kuti J 0 and Felker P 1993. A comparison of Opuntia fruit quality and
winter hardiness for use in Texas. Journal of Arid Environments 24:37-46.
Grif1ith D 1905. The prickly pear and other cacti as food for livestock. USDA- Bur.
Plant Ind. Bull. 74 46 pp.
Guastella G 1913. Coltivazione del fico d'india. Catania: Battiano, F. 63 pp.
Gurrieri S, Miceli L, Lanza M L, Tomaselli F, Bonomo P Rand Rizzarelli E 2000.
Chemical characterization of Sicilian prickly pear (Opuntia ficus-indica ) and
perspectives for the storage of its juice. Journal of Agricultural and Food
Chemistry 48: 5424-5431.
Hill F S 1995. Anatomy and morphology. In: Barbera G, Inglese Pand Pimienta-Barrios
E. (eds.), Agro-ecology, cultivation and uses of cactus pear, pp 78-90. FAO Plant
Production and Protection paper 132: 28-35.
Hoffmann W 1979. Kaakteen als Nutzptlanzen unter besonderer Berucksichtigung der
Gattung Opuntia Mill. Thesis, Universitat Glessen, Glessen.
Hoffmann W 1983. Soziokulturelle undwirtsehaftssoziologische
Implikationenmodernisierender Innovationen in der wirtschaftslichen Nutzung
von Kakteen, dargestellt am Beispiel des Opuntien- Anbaus
imzentralmexikanischen Hochland. PhD Diss.Universitat Glessen.
Inglese P 1993. FAO Plant production and Protection. Paper 132. Rome, Italy.
100
Inglese P, Barbera G, La Mantia Tand Portolano S 1994a. The effect of pruning on
growth and ultimate size of cactus pear fruits. Journal of Horticultural Science.
Inglese P, Barbera G, La Mantia Tand Portolano S 1994b. The Research strategies
and improvement of cactus pear fruit quality and production. Journal of Arid
Environments. 27: 214 - 222.
Inglese P 1995. Orchard planting and management. In: Barbera G, Inglese Pand
Pimienta-Barrios E. (eds.), Agro-ecology, cultivation and uses of cactus pear, 78-
90 pp. FAO Plant Production and Protection paper 132: 213.
Inglese P and Pace L S 2000. Root confinement affect canopy growth, dry matter
partitioning, Carbon assimilation and field behaviour of Opuntia ficus-indica
potted plants. Proceedings of the the fouth International Congress on Cactus Pear
and Cochnille, Tunisia 516: 97 - 106
Instituto Nacional de Investigaciones Forestales 1983. El nopal. Comisión Nacional de
las Zonas Aridas. México. 85 pág.
Knight R 1980. Origin and world importance of tropical and subtropical fruit crops, pp
1-120. In: S Nagy and PE Shaw (eds.), Tropical and subtropical fruits.
Composition, properties and uses. AVI, Westport, CT.
Kuti J 0 1992. Growth and compositional changes during the development of prickly
pear fruits. Journal of Horticultural Sience, 67 (6),861 - 868.
Lahsasni S, Kouhila M, Mahrouz M and Jaouhari J T 2003. Drying kinetics of
prickly pear fruit (Opuntia ficus-indica). Journal of Food Engineering, 61: 173-
179.
101
Le Houérou N H 1971. Les bases écologiques de l'amélioration de la production
fourragêre en Algérie. Rome: Division Production et Protection Végétales, FAO.
58 pp. Multigraph.
Le Houérou N H 1982. The arid bioelimate in the Mediterranean isoelimatie zones.
Ecologia Mediterrania 8: 103-114.
Le Houérou N H 1983. Production of shrub regrowth after cutting at Wishtata
arboretum. UNTFlLib: 18, FAO Agri. Res. Cent. Tripoli, Lybia, techno Paper no.
49.10pp.
Le Houérou N H 1986. Salt tolerant plants of economic value in the Mediterranean
Basin. Reclamation and Revegetation Research 5: 319-341.
Le Houérou N H 1989. The shrubland in Africa. In: MCkell C M (ed.) The biology and
utilization of shrubs, Academic press, N. Y. pp 119-144.
Le Houérou N H 1989. An assessment of the economic feasibility of fodder shrub
plantation, with particular reference to Africa. In: MCkell C M (ed.) The biology
and utilization of shrubs, pp 603-630. Academic press, N. Y. 656 pp
Le Houérou N H 1992. The role of Opuntia cacti in the agricultural development of the
Mediterranean arid zones. Segundo Congreso Internacional de Tuna y Cochinilla.
Santiago, Chile, 22-25 Septembre 1992.
Levitt J 1980. Response of plants to environmental stress. VoU!. Water, radiation, salt
and other stress. 2nd ed. Academic Press. New York.
102
Lopez J J, Fuentes J and Rodriquez A 1997. Establecimiento, utilazación y manejo de
nopal rastrero (Opuruia rastrera Weber.) en elsur de Coahuila, Mexico. In:
Memorias de la 7a Reunión Nacional y Sa Reunión Internacional sobre el
Concimiento y Approvechamiento del Nopal. UAAAN, Saltillo, Coah., México.
Maltsberger W A 1991. Feeding and supplementing prickly pear cactus to beef cattle.
In: Proceedings of Second Annual Texas Prickly Pear Council. pp 104-117.
Mauseth J D 1983. Indroduction to cactus anatomy (part 7). Epidermi. Cactus and
Succulent Journal (US). 55: 272-276.
Meyer N Band McClaughlin J L 1981. Economic uses of Opuntia. Cactus and
succulent Journal (US). 53:107-112.
Mizrahi Y Nerd A and Nobel P S 1997. Cacti as crops. Horticultural Review, 18: 291 -
346.
Mizrahi Y and Nerd A 1999. Usage of various cactus species as fruit and vegetables
crop in Israel. VIn Congresso Nacional y el nopal. San luis Potosi, Mexico.
Monjauze A and Le Houérou N B 1965. Le Rêle des Opuntia dans l'economie agricole
Nord Africaine. Extrait du Bulletin de l'Ecole Nationale Supérieure d'
Agriculture de Tunis. 8-9: 85-164.
Moran V C 1980. Interaction between phytophagous insects and their Opuntia host.
Ecological Entomology 5: 153-164.
Mulas M and D'hallewin G 1990. Improvement of pruning effects on vegetative and
yielding behaviour in Prickly pears (Opuntia ficus-indica Mill). "Gialla"
cultivar.Acta Hort.
103
Musmara A 1937. L'Opuntia. Torino: Borch. 122 pp.
Nerd A, Karadi A and Mizrahi Y 1991. Out of season prickly pear: fruit characteristics
and effects of fertilization and short droughts on productivity. Journal of
Horticultural Science 26: 527-529.
Nerd A, Mesika Rand Mizrahi Y 1993. Effects of N fertilizers on autumn floral flush
and cladode in prickly pear Opuntia ficus-indica (L) Mill. Journal of
Horticultural Science 68: 545-550.
Nobel P S 1983. Spine influence on PAR interception, stem temperature and nocturnal
acid accumulation. American Journal of Botany 70 (8): 1244-1253.
Nobel P S 1986. Form and orientation in relation to PAR interception by cacti and
agaves. In: T.J. Givnish (ed). On the economy of plant form and functions.
Cambridge Univ. Press, New York.
Nobel PS 1994. Remarkable agaves and cacti. OxfordUniv. Press, New York.
Ochoa de Cornelli J 1993. EI cultivo aprovechamiento del nopal en la Republica de
Argentina. August 18-20, 1993. Guadalajara, Jalisco, Mexico.
Oelofse R M 2002. Characterization of Opuntia ficus-indica cultivars in South Africa.
Unpublished. MSc. thesis, University of Free State, Bloemfontein. pp 30-69.
Palomo GDR 1963. Datos sobre los nopales utilizados como forrage de invierno en el
Noreste de México. Tesis Profesional, Escuela de Agricultura y Granaderia,
ITESM, Monterrey, México.
104
Pimienta-Barrios E and Engleman EM 1985. DesarroIlo de la pulpa y proporcio en
volumen de los componentes delloculo maduro en tuna (Opuntiaficus-indica).
Ágrociencia. 62: 51-56.
Pimienta-Barrios E 1990. EI nopal tunero. Univ. de Guadalajara, Mexico.
Pimienta-Barrios E 1993. Vegetable cactus pear (Opuntia spp.). pp 177 - 191, In:
Underutilized crops, Pulses and Vegetables. Chapman and Hall.
Pimienta-Barrios E Loera-Quezada M and Lopez-Amezcua LL 1993. Estudio
anatómico comparativo en colectas del subgenero Opuntia. Agrociencia, series
Fitociencia, 4: 7 - 14.
Pimienta-Barrios E 1994. Prickly pear tOpuntia spp.): a valuable fruit crop for the semi-
arid lands of Mexico. Journal of Arid Environments. 27: 309-316
Pimienta-Barrios E and Mufios-Urias A 1995. Domestication of Opuntias and
cultivated varieties. Agroecology, cultivation and uses of cactus pear. FAO Plant
Production and Protection paper, 132: 58-63
Pimienta-Barrios E Barbera G and Inglese P 1993. Cactus pear (Opuntia spp.
Cactaceae) International Network. An effort for productivity and environmental
conservation for arid and semi arid lands. Cactus and Succulent Journal 65: 225-
229.
Pluenneke R H 1990. Prickly pear work at the R.W. Williams Ranch in Dimmit County
Texas in the 1960s. In: Proceedings of First Annual Texas Prickly Pear Council,
Kingsville, TX. 22-26 pp.
105
Potgieter J P 1993. The spineless prickly pear, saltbush and American Aloe as drought-
tolerant fodder and forage crops for the drier Northern Transvaal areas. Delftzyl
farmers day, Northern Transvaal, South Africa.
Potgieter J P 1995. The cactus pear (Opuntia ficus-indicaï in South Africa: cultivation
and research in the Northern Province (review paper) 6th National and 3rd
International Cactus pear Congress, 3 - 10 November 1995, Guadalajara, Mexico.
Potgieter J Pand Mkhari J J 2002. Evaluation of cactus pear (Opuntia spp) germplasm
for fruit production purposes. Combined Congress of South Africa Society for
Crop Production and South African Society for Horticultural Science,
Petermaritzburg, Natal.
Ramakatane E M 2003. Root dynamics and water studies on Opuntia ficus-indica and
O. robusta unpublished M. Sc. thesis, University of the Free State, Bloemfontain.
94 pp.
Riveros, E Garcia de Cortázar Vand Garcia G 1990. Uso de cladodios de tuna
(Opuntia ficus-indica) como suplemento forrajero estival para ovinos en
crecimiento. Avances en Producción Animal 15(1-2): 81-88.
Rizza A 1960. Spirimenti sulla coltura del nopal in Siracusa. Ann. di Agric. Siciliana 7
(2): 157.
Rodriguez-Félix A M I and CantweIl (de Trojo M 1988). Development changes in the
composition and quality of prickly pear cactus cladodes (nopalitos). Plant Food
for Human Nutrition 38:83-93.
Russel C E and Felker P 1985. The prickly pear (Opuntia spp.y; In: Management and.
utilization of arid land plants. Symposium Proceedings. Saltillo, Mexoco. 41 - 46
pp
106
Russel C E and Felker P 1987. The prickly pear (Opuntia spp. Cactaceae): A source of
human and animal food in semi-arid regions. Economic Botany 41: 433-445 pp.
SAG 1976. Gultivo de tunale. Boletin Divulgativo N° 44 (Ceditec. 0/15/77.1.500 aja.
11/3/77. R - 30) (An extension publication of the Chilean Agricultural Service)
35 pp.
Sáenz C Sepïilvedá E and Matsuhiro B 2004. Opuntia spp mucilage: a functional
component with industrial perspectives. Journal of Arid Environment. In press.
Santana P 1992. Tunas forrajeras (Opuntia ficus-indica y Nopalea cochenillifera) en el
nordeste brasilefio: una revisión. Aetas II Congreso Internacional de la tuna y
cochinilla. Facultad de Ciencias Agrarias y Forestales, Universidad de Chile.
Santiago, 22 al 25 de septiembre de 1992. pp. 126-142.
Santos dos D C and Albuquerque de S G 2001. Opuntia as fodder in the semi-arid
Northeast of Brazil. pp 37-50 pp. In: FAO cactus (Opuntia spp.) as forage, FAO
Plant Production and Protection paper, 169.
Schirra M 1996. Hot dips and high-temperature conditions to improve shelf quality of
late-crop cactus pear fruit. Tropical Science 36: 159 - 165.
Silva Hand Acevedo E 1985. Introducción y adaptación de Opuntia spp. en el secano
mediterráneo árido de la IV Región. Informe final. Proyecto 0065. Fondo Nacinal
de DesarroIlo Cientifico y Tecnológico (FONDECYT). 136 pág.
Smith C E 1967. Plant Remains. In: The pre-history of the Tehuacan Valley.
Environment and Subsistence. Austin.
107
Snyman H A 1998. Dynamics and sustainable utilization of rangeland ecosystems in arid
and semi-arid climates of southern Africa. Journal of Arid Environments 39 C4):
645-666.
Snyman HA 2003. Root dynamics of cactus pear. Agri TY. http://www.agrictv.co.za 25
October 2003: 1-2 pp.
Soil Classification Working Group 1991. Soil classification. A taxonomic system for
South Africa. Memoirs on the Agricultural Natural Resources of South Africa No.
15. Department of Agricultural development, Pretoria, South Africa.
Tekelenburg A 1993. Prickly pear and cochineal production as an integral component of
rural development Manuscript.
Van der Merwe L L, Wessels A B, Ferreira D I 1997. Supplementary irrigation for
spineless cactus pear. Third International Congress of Cactus Pear and Cochnille,
Midrand South Africa. Acta Horticulturae 438: 77-82.
Wessels A B 1988. Spineless prickly pear. Perskor, Johannesburg, South Africa.6l pp.
Wessels A B and Swart E 1990. Morphogenesis of the reproductive buds and fruit of
prickly pear Opuntia ficus-indica CL) Mill. cv. Morado. Acta Hort. 275: 245-253
pp.
Zudzuki F G, Azocar M Pand Lailhacar S 1990. Bases ecológicas
para el desarroIlo agropecuario de la zona de clima mediterráneo árido de Chile.
Terra Arida 8:221-30l.
107
Appendix
Table A.1 The P-values and least significant differences (LSD) for the different treatments and cultivars (P:S;O.05 level of
significance).
Variable P-Values LSD
Treatment Cultivar Treatment Cultivar
Width 0.9328 0.0205 0.022 0.665
Height 0.8889 0.0083 0.0285 0.0746
No. cladodes (2nd year) 0.8166 0.0069 0.1239 0.4381
No. cladodes (3r<!year) 0.0391 0.0252 0.152 0.9692
No. cladodes pruned 0.7948 0.001l 0.2284 0.4925
Cladode fresh mass 0.947 0.2798 0.0067 0.0518
Cladode dry mass % 0.5626 0.5455 2.27 6.3856
Cladode dry mass (plant -I) 0.8669 0.0102 0.0001 0.0001
Cladode dry mass (ha -I) 0.87 0.0210 0.12 0.12
Frost damage % (2/8/02) 0.1441 0.0442 2.3312 17.007
Frost damage % (4/10/02) 0.0692 0.1302 1.186 1.6329
Frost damage % (14/9/03) 0.0339 0.0119 6.649 32.0101
No. fruits 0.0216 0.0005 0.1408 0.2981
Fruit mass 0.002 0.0096 21 27.2822
Fruit yield (plant -I) 0.0298 0.0013 0.0171 0.0235
Fruit yield (ha -I) 0.0336 0.0023 20.52 28.20
-Pee_l th.ickness _ 0.0002 0.0057 1.4688 1.534_. .. -- - _. -
108
Table A.2 The monthly summary of climatic data for Welgegund (experimental site) over three growing seasons (200112002 to
2003/2004).
200112002 Growing season
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
Radiation 26.1 25.0 2l.0 18.2 13.9 13.0
Average temperature 2l.6 2l.2 19.9 16.4 10.4 7.0
Average humidity 62.7 6l.3 62.0 56.2 67.0 72.0
Average wind speed 2.3 l.8 l.5 1.4 l.5 1.4
Total rainfall 0.0 45.0 6.0 104.0 182.0 120.0 59.3 55.6 1l.7 2l.8 57.9 14.0
Average maximum temperature 29.1 29.2 28.4 26.3 20.1 16.3
Absolute maximum temperature 32.8 34.0 32.5 30.8 27.0 20.7
Average minimum temperature 14.4 14.1 12.3 7.5 2.6 -0.4
Absolute minimum temperature 7.8 8.7 2.1 -0.1 -3.3 -4.7
Average maximum humidity 9l.1 9l.2 9l.5 86.6 93.7 96.6
Average minimum humidity 3l.4 28.4 29.5 23.5 32.4 35.3
Average evaporation 5.7 2.7 4.9 3.8 2.5 2.0
Total cold units 0.0 0.0 0.0 7.5 172.0 256.5
Total heat units 362.6 336.2 319.6 207.4 61.1 0.4
Average rainfall Tweespruit 13.2 22 28 84 87.9 7l.8 77.4 96.4 87.9 59.6 25.4 14.1
Average rainfall Glen 8.7 11.5 18.9 48.6 68.1 66.1 83.6 80.7 83.5 50.5 18.6 8.7
Cumulative Ave rainfall Glen 8.7 20.2 39.1 87.7 155.8 221.9 305.5 386.2 469.7 520.2 538.8 547.5
Cumulative rainfall Welgegund 0.0 45.0 51.0 155.0 337.0 457.0 516.3 571.9 583.6 605.4 663.3 677.3
109
2002/2003 Growing season
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
Radiation 15.0 14.9 19.5 24.5 27.2 23.6 27.7 22.7 22.4 18.6 14.1 14.2
Average temperature 6.3 1l.2 14.3 18.5 19.3 20.9 22.8 22.4 19.7 18.0 10.5 6.3
Average humidity 58.5 64.8 60.8 47.9 47.0 64.7 57.2 65.9 6l.9 62.5 64.2 55.4
Average wind speed l.7 2.0 l.9 2.3 2.6 2.3 2.3 l.7 l.8 1.3 1.3 1.1
Total rainfall 0.1 78.3 22.6 25.3 18.1 82.2 95 89.9 67.3 1.8 3.5 0
Average max temperature 17.0 20.4 23.1 27.4 27.6 28.1 30.8 29.3 28.1 27.1 20.4 17.9
Absolute max temperature 24.9 24.8 29.2 34.4 33.5 34.7 35.6 35.7 33.5 30.3 25.1 22.6
Average min temperature -2.6 3.6 6.1 9.7 10.6 14.6 15.5 16.6 12.0 10.0 2.1 -2.9
Absolute min temperature -7.5 -3.7 0.6 -2.1 3.7 11.9 10.7 13.9 4.7 3.1 -3.6 -8.1
Average max humidity 89.6 90.8 91.4 81.6 78.5 91.4 89.6 93.7 91.7 93.3 92.2 85.7
Average min humidity 23.1 32.2 27.2 19.6 18.6 33.9 25.5 35.5 30.4 27.7 29.8 22.8
Average evaporation 2.6 2.8 3.8 5.4 6.2 5.2 6.3 4.9 4.7 3.8 2.5 2.4
Total cold units 180.5 158.5 80.5 15.5 14.0 0.0 0.0 0.0 24.5 3.5 135.0 112.5
Total heat units 5.3 71.4 145.0 261.6 269.3 350.3 397.0 . 358.1 309.3 170.5 48.1 3.9
Average rainfall Tweespruit 13.2 22 28 84 87.9 71.8 77.4 96.4 87.9 59.6 25.4 14.1
Average rainfall Glen 8.7 11.5 18.9 48.6 68.1 66.1 .83.6 80.7 83.5 50.5 18.6 8.7
Cumulative average rainfall Glen 8.7 20.2 39.1 87.7 155.8 221.9 305.5 386.2 469.7 520.2 538.8 547.5
Cumulative rainfall Welgegund 0.1 78.4 lOl.O 126.3 144.4 226.6 32l.6 41l.5 478.8 480.6 484.1 484.1
110
2003/2004 Growing season
Jul Aug Sep Oct Nov Dec Jan Feb Mch Apr May Jun
Radiation 14.9 17.5 20.8
Average temperature 6.5 8.0 14.8
Average humidity 51.3 66.0 78.7
Average wind speed 1.2 1.7 2.3
Total rainfall 0.0 0 1.7
Average max temperature 18.1 19.5 24.2
Absolute max temperature 21.5 27.6 30.9
Average min temperature -2.8 -2.5 5.8
Absolute min temperature -6.3 -9.6 -1.9
Average max humidity 80.5 93.1 99.6
Average min humidity 23.0 28.4 48.7
Average evaporation 2.5 2.9 3.8
Total cold units 93.5 106.5 40.5
Total heat units 5.4 19.9 141.4
Average rainfall Tweespruit 13.2 22 28 84 87.9 71.8 77.4 96.4 87.9 59.6 25.4 14.1
Average rainfall Glen 8.7 11.5 18.9 48.6 68.1 66.1 83.6 80.7 83.5 50.5 18.6 8.7
Cumulative average rainfall Glen 8.7 20.2 39.1 87.7 155.8 221.9 305.5 386.2 469.7 520.2 538.8 547.5
Cumulative rainfall Welgegund 0.0 0.0 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7