Masters Degrees (Soil, Crop and Climate Sciences)
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Browsing Masters Degrees (Soil, Crop and Climate Sciences) by Advisor "Engelbrecht, G. M."
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Item Open Access Effect of liquid Maxiflo (Azospirillum SPP) and Trykoside (Trichoderma SPP) cultures on the growth and yield of selected crops(University of the Free State, 2006) Mashamba, Nwagu Rodney; Pretorius, J. C.; Engelbrecht, G. M.English: The challenge for science is to address the need for adequate food provision and a sustainable future for agriculture. The solution for increasing food production can probably only be obtained through expansion of arable land, by increasing irrigation practices or by increasing harvestable yields on available land through the improvement of agricultural technology. With regard to the latter approach, field experiments were conducted at the experimental farm of the University of the Free State, Bloemfontein, during the 2003 and 2004 growing seasons, to determine the effect of Maxiflo and Trykoside (liquid formulations of Azospirillium and Trichoderma based products, respectively) on vegetative growth and yield of two leafy vegetable crops (cabbage and lettuce), a cereal crop (wheat), a fruit crop (tomato), a tuber crop (potato) and a legume crop (peas). A randomized complete block design with six treatments (Control, Maxiflo, Trykoside, Maxiflo + Trykoside, ComCat® and Ke/pak®) was applied in all cases. Maxiflo and Trykoside were applied either separately or together. Two commercially available natural bio stimulants, ComCat® and Ke/pal<®, served as positive controls. Different growth and yield parameters were used to quantify the effect of the test products in the above six economically important crops. In cabbage and lettuce vegetative growth (plant height, plant diameter and stem thickness) were not affected but a significant increase in head mass was observed. Peas were most responsive to treatment with the bio-products in terms of the increase in yield obtained. Treatment with Maxiflo and Trykoside in combination increased the medium/large and large size fruit yield in tomatoes while exactly the same was observed for tuber size in potatoes. However, in both crops the total yield was not significantly affected. In wheat root growth was stimulated significantly by treatment with Trykoside but no significant yield increase was observed at the 5% probability level (P<0.05).Item Open Access The effect of nitrogen fertilisation on the growth, yield and quality of swiss chard (Beta vulgaris var. cicla)(University of the Free State, 2008-05) Motseki, Pontso Christina; Engelbrecht, G. M.; Ceronio, G. M.English: The sustainability of subsistence farming associated with the health of rural communities’ necessitated research on Swiss chard as it forms an integral part of food consumed by the poor in developing countries. Two separate pot experiments were carried out during the 2005/06 and 2006/07 seasons in the glasshouse of the Department of Soil, Crop and Climate Sciences at the University of the Free State. The objective of this study was to determine the effect of nitrogen fertiliser on growth, yield and quality of Swiss chard. The first pot trial was conducted to evaluate the effect of five nitrogen levels (0, 50, 100, 200, 400 kg N ha-1) and four application times on the growth, yield and quality of two Swiss chard cultivars (‘Fordhook Giant’ and ‘Rhubarb’). Two Swiss chard seedlings were planted per pot, filled with topsoil of the fine sandy loam Bainsvlei form. Two weeks after planting plants were thinned to one seedling per pot. Different nitrogen levels were applied to the relevant pots as follows: once every second, fourth, sixth or eighth week. It was only the total dry mass per plant and total nitrogen content per leaf of ‘Rhubarb’ plants that was significant higher than that of ‘Fordhook Giant’. The other parameters measured for the two cultivars did not differ significantly from each other. Nitrogen levels positively influenced the early growth, yield and quality parameters measured. It was the highest nitrogen level (400 kg N ha-1) that resulted in the highest number of leaves harvested, leaf fresh and dry mass, leaf area and leaf nitrogen content. Nitrogen application times significantly influenced only the early growth of Swiss chard plants and the nitrogen content of leaves. Early plant growth reacted better where nitrogen was split into three equal applications (T4). The total nitrogen content of Swiss chard leaves was significantly higher where nitrogen was split into five equal (T2) or three equal (T4) applications. In the second pot trial the effect of different nitrogen sources applied at different levels on the growth, yield and quality of Swiss chard cultivars was determined. The response of Swiss chard plants to nine nitrogen levels (0, 100, 200, 300, 400, 500, 600, 700, 800 kg N ha-1) from six different nitrogen sources (ammonium nitrate, potassium nitrate, calcium nitrate, ammonium sulphate, urea ammonium nitrate and urea) were studied. Based on the findings of this study, nitrogen significantly influenced growth, number of leaves harvested, leaf fresh and dry mass, leaf area and leaf nitrate content of ‘Fordhook Giant’ plants with best results obtained at 800 kg N ha-1. Nitrogen sources did not influence either the total number of leaves harvested nor the fresh mass of harvested Swiss chard leaves. In both cases, ammonium nitrate gave the best results and calcium nitrate the poorest. Urea influenced the leaf area positively followed by urea ammonium nitrate, with calcium nitrate resulting in the smallest leaf area per plant. Dry mass of Swiss chard leaves was also significantly higher where urea was used as nitrogen source compared to where calcium nitrate was used. No significant differences amongst the other nitrogen sources. Ammonium nitrate and potassium nitrate significantly stimulated the accumulation of nitrate in Swiss chard leaves, whereas the other nitrogen sources did not play any role in nitrate accumulation in the leaves of Swiss chard.Item Open Access The effect of plant population and mulching on green pepper (Capsicum annuum L.) production under irrigation(University of the Free State, 2010-11) Hatutale, Gervasius; Engelbrecht, G. M.; Van Rensburg, L. D.English: Green pepper (Capsicum annuum L.) is gaining popularity and the production and consumption thereof is increasing worldwide. Semi-arid regions are characterized by variable and unreliable rainfall which necessitates the use of irrigation for sustainable green pepper production. In this study two field trials were conducted. Objectives of the first trial were to quantify the effect of irrigation and plant population on the growth and yield of green pepper and to optimize its plant population for different water regimes. Four water treatments, full irrigation (781 mm), 70% of full irrigation (627 mm), 40% of full irrigation (497 mm) and dryland (303 mm) and five plant populations (17 689, 23 674, 29 526, 34 979 and 41 496 plants ha-1) were used in this trial. A line source sprinkler irrigation system was used for water application. The trial layout was a split plot design with water applications as main treatments and plant populations as sub-treatments. All treatment combinations were replicated four times. The full irrigation and 40% of full irrigation treatment increased marketable yield with 274% and 162%, respectively. The 70% of full irrigation treatment increased marketable yield with 253%. The marketable yield of all irrigation treatments was significantly higher than that of the dryland treatment. The full irrigation’s marketable yield was however also significantly higher than that of 40% of full irrigation treatment. The optimum plant population for all water treatments, excluding 40% of full irrigation was not reached in this trial because the yield of plant populations (17 689 to 41 496 plants ha-1) used did not reach a turning point, but still increased linearly beyond 41 496 plants ha-1. The objective of the second trial was to quantify the effect irrigation and mulching on yield, water use and water use efficiency. Four water treatments, full irrigation (547 mm), 66% of full irrigation (481 mm), 33% of full irrigation (417 mm) and dryland (303 mm) and two mulching (bare and 9 t ha-1 maize straw) treatments were used. A line source sprinkler irrigation system was also used for this experiment. The trial layout was a split plot design with water treatments as main treatments and mulching rates as sub-treatments. All treatment combinations were replicated four times. Results indicated that green pepper responded well to irrigation. Full irrigation, 66% and 33% of full irrigation treatment produced marketable yield of 37.54, 29.74 and 20.52 t ha-1, respectively. The marketable yield of irrigation treatments was significantly different from each other and they were all significantly higher than that of the dryland treatment which produced a marketable yield of 11.92 t ha-1. As irrigation proceeded over time, the relationship between water use and leaf area index strengthened. The fully irrigated treatment produced the highest water use efficiency. Mulching conserves water by reducing evaporation and mitigates negative effects of water stress on plant growth and yield under semi-arid conditions. At the end of the season, cumulative water use efficiency from the mulched treatment was 6 g m-2 mm-1, significantly higher than that of the bare treatment of 5.3 g m-2 mm-1. Green pepper is very susceptible to water stress and produces poorly under dryland conditions and any irrigation is beneficial to its production. However results also indicated that green pepper has the ability to adapt quite well to high plant populations and has demonstrated its ability to compete for production resources at such populations. The crop also conforms well to the favourable plant growth conditions provided by the mulch. Keywords: marketable yield, water use, water use efficiency, leaf area index, dryland, full irrigationItem Open Access Grafting of walnut (Juglans regia L.) with hot callusing techniques under South African conditions(University of the Free State, 2009-04) Van Zyl, L. C.; Bothma-Schmidt, A.; Engelbrecht, G. M.English: One of the biggest constraints to the expansion of the walnut industry in South Africa, is the availability of good quality and cost effective plant material. Since walnuts are more difficult to propagate vegetatively than most fruit and nut species, controlled conditions are required to ensure grafting success. Hot callus grafting is a bench grafting procedure subjecting grafted trees to controlled, elevated temperature and humidity, and has been implemented successfully in several countries to increase grafting success of walnut. Until now, hot callus grafting has not been investigated as a possible walnut propagation method in South Africa. The present study assessed method of heat supply and time of grafting, as important factors determining grafting success of two walnut cultivars grafted onto Juglans regia rootstocks under hot callus conditions. Although neither method of heat supply provided definite superior grafting success, localized heating of graft unions in a heated trench, gave more consistent results than heating the entire grafted tree in a heated room. Both methods seemed promising, since acceptable grafting success was obtained in some instances with both the heated trench and room. Post-grafting shoot growth on the other hand, was significantly higher for the heated trench than for the room. Both methods did, however, result in trees of a suitable size for orchard establishment after only one growing season. Results further indicated that exposure to increased temperature for a period of 25 days is more than sufficient for callus development of walnut, and very little is gained by heating grafted trees for longer. Earlier grafting, before the onset of bud break of cultivar and/or rootstock, generally resulted in improved grafting success and drastically increased shoot growth during the first growing season, providing grafted trees of saleable size in a shorter time. There were no clear differences regarding callus formation, grafting success or survival between the two cultivars evaluated, ‘Chandler’ and ‘Serr’. As expected, more vigorous post-grafting growth was observed for ‘Serr’, since it is the more vigorous grower of the two. A separate hot callus grafting trial, using Paradox rootstocks, also indicated that the type of rootstock utilized in hot callus grafting may impact grafting success. More consistent results were obtained with all four cultivars grafted onto this hybrid rootstock, than with J. regia rootstocks in the preceding trial. For both J. regia and Paradox rootstocks, survival of trees through the first growing season was still unacceptably low, although results were comparable to that of other studies. Since results were available for a single season only, conclusions should be regarded as preliminary. Nevertheless, findings clearly illustrated the potential value of hot callus grafting as propagation method for walnut in South Africa and lay a foundation for the establishment of propagation guidelines using this approach.Item Open Access Improvement of the nitrogen content of grape must with fertilisation(University of the Free State, 2002-11) Jordaan, Jacques; Engelbrecht, G. M.; Du Preez, C. C.English: Stuck fermentation is currently a serious production associated problem in the South-African wine industry. This can mainly be attributed to insufficient levels of nitrogen in grape must, thus are not being able to supply in yeast demands. This study was undertaken to investigate whether the nitrogen content of grape must can be improved by fertilisation. In order to achieve this three nitrogen application treatments (N1C = 20 kg N/ha-¹ post-harvest; N2F = 20 kg N/ha-¹ post-harvest, followed with 20 kg N/ha-¹ after budbreak and fruitset respectively; and N2V = 20 kg N/ha-¹ post-harvest, followed with 20 kg N/ha-¹ after budbreak and veraison respectively), were applied to six grape cultivars (Cabernet Sauvignon, Chenin blanc, Pinot noir, Weisser Riesling, Chardonnayand Pinotage) for two seasons (1999/2000 = 1st season and 2000/2001 = 2nd season). The vineyard is situated on a high potential loam soil, classified as a red-brown Oakleaf, with a mean organic matter content of 1.4%. The effect of these nitrogen application treatments on the growth characteristics, grape must composition, leaf nitrogen content, as well as the soil nitrate content, were measured. Nitrogen applications during the vegetative phase had a positive effect on the shoot length and shoot elongation during both seasons, although more so during the 1st season. The pruning mass was significantly affected by cultivar during both seasons. Treatments receiving no nitrogen fertilisation during the vegetative phase (N1C) resulted in higher free amino nitrogen (FAN) and FAN/oB ratio in grape must, indicating a negative reaction to nitrogen fertilisation for soils having a high organic matter content. No nitrogen fertilisation during the vegetative season resulted in significantly lower bunch and berry mass values than those receiving fertilisation. This might indicate a negative relationship between bunch and berry mass and the FAN content of grape must. The nitrate content of the soil differed for the different soil depths and was affected by sampling date and N treatments. Results indicated that 70% of the nitrate was available in the top 30 cm of soil. Nitrogen fertilisation during the vegetative season on soils with an organic matter content of 1.4% should be strongly discouraged. This study therefore indicates that although high organic matter content and inorganic fertiliser applications may increase the nitrate content of the soil, this might not have the same effect on the nitrogen status of the vine.Item Open Access Influence of organic fertilisers on the yield and quality of cabbage and carrots(University of the Free State, 2008-11) Mbatha, Alice Nompumelelo; Engelbrecht, G. M.; Ceronio, G. M.English: The use of organic fertiliser as an alternative to inorganic fertiliser increased among subsistence farmers in rural areas in KwaZulu Natal. No clear recommendations exist for the application of different organic fertilisers on vegetables. Two field trials were conducted at Umsunduze Training Centre, KwaZulu Natal during the 2005 and 2006 seasons. The effect of three different organic fertilisers (chicken, kraal manure and compost) were investigated on the growth, yield and quality of cabbage cv. Conquistador and carrots cv. Kuroda. Four application rates were used for each organic fertiliser (chicken manure: 0, 6.25, 12.5 and 25 kg 10 m-2; kraal manure: 0, 12.5, 25 and 50 kg 10 m-2; compost: 0, 25, 50 and 100 kg 10 m-2). Each treatment combination was replicated four times. Organic fertilisers were incorporated into the soil one month before planting. Number of leaves and plant height were measured for the first 8 weeks after planting for both crops. Fresh and dry mass was determined at harvesting for both cabbage and carrots. Cabbage head and carrot shoulder diameter, carrot root length and carrot root total soluble solids were measured at harvesting. Both crops were graded (cabbage into 3 and carrots into 5 classes) according to their external appearance. After harvesting, soil analysis (2005 and 2006) and plant analysis (2006) were done for both crops. Chicken manure applied at 12.5 or 25 kg 10 m-2 showed a significant increase in the growth rate of cabbage during the first 8 weeks after transplanting in both seasons. During 2005, fresh mass of cabbage that received 12.5 or 25 kg 10 m-2 chicken manure was significantly higher and of better quality than the other organic fertiliser treatments. In 2006, the fresh mass and quality of cabbage that received 50 kg 10 m-2 kraal manure, 25 kg 10 m-2 chicken manure or 100 kg 10 m-2 compost was significantly higher than the other organic treatments. Dry mass also significantly increased when 25 kg 10 m-2 chicken manure was applied. Compost significantly increased the nitrogen, phosphorus, potassium, sulphur and calcium content, while kraal manure significantly increased the phosphorus, potassium and magnesium content of the soil after two years of application. It was in most cases the two highest application rates (Rate 2 and 3) that significantly influenced the chemical properties of the soil. Only chicken manure significantly influenced the nitrogen content of cabbage heads. Carrot plants that received chicken and kraal manure at Rate 2 or 3 produced the most number of leaves while the tallest carrot plants were obtained where 25 kg 10 m-2 chicken manure or 50 kg 10 m-2 compost was applied, at 8 weeks after planting. Different organic fertilisers and application rates did not significantly influence the fresh mass and root length of carrots. Dry mass of carrots that received 25 kg 10 m-2 chicken manure, 50 kg 10 m-2 kraal manure or 25 kg 10 m-2 compost was significantly greater than plants that did not receive any fertiliser in 2006. High organic fertiliser rates (Rate 3) significantly increased shoulder diameter. In 2005, chicken manure and compost significantly decreased total soluble solid content of carrots. In 2006, the highest total soluble solid content was obtained with 12.5 kg 10 m-2 chicken manure. An increase in the organic fertiliser rate promoted the development of hairy carrots in 2005 and carrots that received compost (Class 3) was of a poorer quality than those that received chicken or kraal manure (Class 2) in 2006. Compost significantly increased the phosphorus, potassium content and NIRS organic matter of the soil and kraal manure only significantly increased the sulphur content of the soil after two years of application. Chicken manure (25 kg 10 m-2) and 100 kg 10 m-2 compost significantly increased the nitrogen content of carrot roots, while the calcium content was significantly lowered where chicken manure was applied. Kraal manure significantly increased the iron content and 6.25 kg 10 m-2 chicken manure increased the total carbon content of carrots.Item Open Access Influence of temperature on yield and quality of carrots (Daucus carota var.sativa)(University of the Free State, 2011-11) Manosa, Nthabiseng Adelaide; Engelbrecht, G. M.; Allemann, J.The influence of temperature on yield and quality of carrots were examined using two pot trials that were conducted in the glasshouse and growth chambers at the Department of Soil, Crop and Climate Sciences, on the Bloemfontein campus of the University of the Free State in 2009 and 2009/10. In the first trial the influence of four temperatures (10, 18, 26 and 32°C) on the growth, yield and quality of two pre-pack carrot cv’s. Nectar and Star 3002 were studied. Carrot seed were sown in 0.34 m x 0.34 m x 0.35 m pots, filled with topsoil of the sandy loam Bainsvlei form. Pots were kept in the glasshouse at 20°C (±1°C) for four weeks to allow the seedlings to establish and reach the first true leaf stage whereupon they were moved to the controlled environment chambers at different temperatures for 20 weeks. Growth parameters such as leaf number, plant height and leaf growth were significantly influenced by temperature and all these parameters performed the best at 10°C at the end of the growth season irrespective of cultivar. Root fresh and dry mass did not differ significantly between the two cultivars but the affect of temperature was significant. The highest root fresh mass for both cultivars was also obtained at 10°C, with “Star 3002” with the highest mass (39.12 g) followed by “Nectar” (34.26 g). Both cultivars exhibited the highest root dry mass at the lower temperature treatment (10°C) with “Star 3002” having a higher root dry mass (4.15 g) than “Nectar” (3.87 g). External quality parameters such as root length and diameter differed significantly between the temperature treatments and only the length of carrot roots did not differ significantly between the cultivars. Both “Nectar” and “Star 3002” exhibited the longest roots at 10°C and the shortest roots at 18°C. Root diameter for both cultivars was significantly greater at 10°C than at 18°C. The only defects observed were green shoulder and misshapen roots. Although not significant, the percentage green shoulders and misshapen roots were higher at 18°C than at 10°C. Carrots were significantly firmer at the low temperature (10°C) than at 18°C. The total soluble solid content of carrots however, grown at 18°C was significantly higher than those grown at 10°C. In the second pot trial the influence of four dual temperatures (15/5, 24/10, 28/20 and 35/25°C) on the growth, yield and quality of two pre-pack carrot cultivars “Nectar” and “CS 1006” was studied. Based on the results of this study, temperature influenced leaf number and plant height of both cultivars, although not always significantly, during the 32 weeks of growth. Leaf number and plant height of carrot plants were greater at 15/5°C treatment. Yield parameters and the external quality parameters such as root length; diameter and absence of defects were also influenced significantly by temperature. Carrot root length and diameter were significantly influenced positively by lower temperatures (15/5°C) and absence of defects such as green shoulder and hairiness were significantly influenced negatively by higher temperatures (28/20°C). Some of the internal quality parameters such as firmness, total soluble solids, carotene, β-pinene and caryophyllene were also significantly affected by temperature. Firmness, total soluble solids and carotene were significantly influenced by lower temperature (15/5°C) whereas β-pinene and caryophyllene were significantly influenced by higher temperatures (28/20°C). Free choice profiling (FCP) was carried out in order to investigate how semi-naïve panelists described and perceived carrot samples cultivated under different temperature conditions. This method allowed participants to use their own attributes to describe and quantify the food product. The FCP procedure generated six descriptors on the attribute taste and one on aftertaste. The two carrot cultivars grown at the higher temperatures (24/10 and 28/20°C) had descriptors like bitter, sour, bland and chemical, with a definite aftertaste while carrot cultivars grown at lower temperatures (15/5°C) had descriptors such as sweet and carrot taste.Item Open Access Response of onion (Allium cepa L.) to sowing date and plant population(University of the Free State, 2014-05-27) Bosekeng, Gagopale; Engelbrecht, G. M.; Allemann, J.Field trials were conducted on the West Campus facility of the Department of Soil, Crop and Climate Sciences of the University of the Free State in Bloemfontein during 2009 and 2010. The first trial during 2009 investigated the response of onion (Allium cepa L.) cultivars to sowing date. Cultivars namely; Charlize, Jaquar, Python and South Wester were used in 2009. Onions were sown on 31 April, 7 May and 21 May during 2009. The second trial was conducted during 2010, where cultivar Ceres Gold was used to replace South Wester as the latter was no-longer available in the market and sowing was done on 11 May, 25 May and 8 June. In both seasons, experiments were laid out as a randomized complete block design with each treatment combination replicated three times. During 2009, plant population of 41 plants m-2 was used, while in 2010 plant population of 61 plants m-2 was used. Plots of 1.8 m2 were used with each plot having five rows. Each row had fifteen plants during 2009 and twenty two plants during 2010. Before planting, soil sampling and analysis were made, thereafter, fertilizers were applied as per soil analysis results. A third field trial was conducted in 2010 to evaluate the three sowing dates (11 May, 25 May and 8 June) with a combination of five plant populations (95, 83, 74, 67 and 61 plants m-2) using one onion cultivar (‘Jaquar’). The experiment was laid out as a randomized complete bock design, with three replications having 1.8 m2 plots. In each plot there were five rows. A bulb storage trial was also conducted under room (±25°C) and cold room temperatures (±5°C). This was done for all field trial in both seasons. In a trial investigating response of cultivars to sowing date, better plant height, number of leaves, bulb fresh mass, and yield were observed when sowing was done from the end of April to the end of May. Sowing date significantly influenced bulb and neck diameters only during 2009. Bulbs were becoming more firm as sowing date was delayed, and the opposite was observed for bolting. Cultivar South Wester bolted more, followed by cultivar Jaquar while other cultivars did not bolt. The shape of bulbs was not significantly influenced by sowing date but it showed to be cultivar authentic. No split bulbs were observed. In a trial of sowing date and plant population, significantly taller plants were obtained with early sowing date than the two later sowing dates. Leaf production was not significantly influenced by sowing date. Sowing date and plant population affected bulb fresh mass, yield, bulb and neck diameters as well as firmness. Sowing date did not influence bulb shape while plant population did. None of the bulbs bolted from this trial. Mid-intermediate day cultivars (‘South Wester’ and ‘Ceres Gold’) recorded the shortest duration (105 days and 63 days respectively), while on average other cultivars were stored for 126 days in 2009 and 105 days in 2010. Storage disease (black mould), sprouting and loss of moisture from the bulbs were the contributing factors for reduction in storage duration. These factors were promoted by both field and storage conditions. Onion producers should have adequate information on the cultivars and the production.Item Open Access Response of onion (Allium cepa L.) to sowing date and plant population(University of the Free State, 2012-06) Bosekeng, Gagopale; Engelbrecht, G. M.; Allemann, J.Field trials were conducted on the West Campus facility of the Department of Soil, Crop and Climate Sciences of the University of the Free State in Bloemfontein during 2009 and 2010. The first trial during 2009 investigated the response of onion (Allium cepa L.) cultivars to sowing date. Cultivars namely; Charlize, Jaquar, Python and South Wester were used in 2009. Onions were sown on 31 April, 7 May and 21 May during 2009. The second trial was conducted during 2010, where cultivar Ceres Gold was used to replace South Wester as the latter was no-longer available in the market and sowing was done on 11 May, 25 May and 8 June. In both seasons, experiments were laid out as a randomized complete block design with each treatment combination replicated three times. During 2009, plant population of 41 plants m·2 was used, while in 2010 plant population of 61 plants m·2 was used. Plots of 1.8 m2 were used with each plot having five rows. Each row had fifteen plants during 2009 and twenty two plants during 2010. Before planting, soil sampling and analysis were made, thereafter, fertilizers were applied as per soil analysis results. A third field trial was conducted in 2010 to evaluate the three sowing dates (11 May, 25 May and 8 June) with a combination of five plant populations (95, 83, 74, 67 and 61 plants rn") using one onion cultivar ('Jaquar'). The experiment was laid out as a randomized complete bock design, with three replications having 1.8 m2 plots. In each plot there were five rows. A bulb storage trial was also conducted under room (±25°C) and cold room temperatures (±5°C). This was done for all field trial in both seasons. In a trial investigating response of cultivars to sowing date, better plant height, number of leaves, bulb fresh mass, and yield were observed when sowing was done from the end of April to the end of May. Sowing date significantly influenced bulb and neck diameters only during 2009. Bulbs were becoming more firm as sowing date was delayed, and the opposite was observed for bolting. Cultivar South Wester bolted more, followed by cultivar Jaquar while other cultivars did not bolt. The shape of bulbs was not significantly influenced by sowing date but it showed to be cultivar authentic. No split bulbs were observed. In a trial of sowing date and plant population, significantly taller plants were obtained with early sowing date than the two later sowing dates. Leaf production was not significantly influenced by sowing date. Sowing date and plant population affected bulb fresh mass, yield, bulb and neck diameters as well as firmness. Sowing date did not influence bulb shape while plant population did. None of the bulbs bolted from this trial. Mid-intermediate day cultivars ('South Wester' and 'Ceres Gold') recorded the shortest duration (105 days and 63 days respectively), while on average other cultivars were stored for 126 days in 2009 and 105 days in 2010. Storage disease (black mould), sprouting and loss of moisture from the bulbs were the contributing factors for reduction in storage duration. These factors were promoted by both field and storage conditions. Onion producers should have adequate information on the cultivars and the production In a trial of sowing date and plant population, significantly taller plants were obtained with early sowing date than the two later sowing dates. Leaf production was not significantly influenced by sowing date. Sowing date and plant population affected bulb fresh mass, yield, bulb and neck diameters as well as firmness. Sowing date did not influence bulb shape while plant population did. None of the bulbs bolted from this trial. Mid-intermediate day cultivars ('South Wester' and 'Ceres Gold') recorded the shortest duration (105 days and 63 days respectively), while on average other cultivars were stored for 126 days in 2009 and 105 days in 2010. Storage disease (black mould), sprouting and loss of moisture from the bulbs were the contributing factors for reduction in storage duration. These factors were promoted by both field and storage conditions.