Characterization of Opuntia ficus-indica cultivars in South Africa

Abstract

English: Spineless cactus pear [Opuntia ticus-indice (L.) MilL] 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. The aim of this study was to contribute to such a database on horticultural, fodder, genetical and pathoglogical level. 2. Plantmaterial of the 10 cultivars were obtained from a genebank situated near Potgietersrus in the Northern Transvaal (230 50'S), South Africa. This area has a subtropical climate with predominantly summer rainfall. The cultivars were characterised on general horticultural characteristics, characteristics for use as fodder and resistance to four pathogens obtained from infected cactus pear orchards in South Africa. The cultivars were also genetically characterised using the AFLP method. 3. All the morphological results obtained were compared with the genetical data. The results obtained showed that morphological data, whether horticultural, fodder or pathological, are inadequate to distinguish and characterise the different cultivars. DNA fingerprinting can complement this characterisation. 4. The fact that the major clustering in the morphological and pathological dendrograms does not correlate with the AFLP dendrogram proves that low correlation exist between the subset of DNA related to morphological characters, the subset of DNA related to pathology and a random sampling of the total genomic DNA. It also underlines the unreliability of using only morphological and pathological descriptors in selection. In order to solve this problem, further description and characterisation of these cultivars is needed, but in the different cactus pear production areas in South Africa in order to better understand the influence of the environment on these cultivars. Description and characterisation of the cultivars in terms of a wider set of parameters, for instance resistance to a wider range of pathogens and cold tolerance is also needed in order to make the morphological and pathological data more reliable. 5. It is clear from the literature that O. ficus-indice is a multifunctional crop, which can be of great value in both developed en undeveloped countries, because of its ability to utilise the full potential of arid areas, though in South Africa the full potential of cactus pear is not utilised yet. It is clear from the morphological and pathological data in this study that the 10 commercial cultivars in South Africa compare well to other cultivars described in the literature.

Afrikaans: 1. O. ficus-indica (L.) Mill. in Suid-Africa word toenemend gekommersialiseer en daar het 'n behoefte ontstaan na 'n databasis wat produsente kan riglyne gee vir seleksie van kultivars vir produksie doeleindes. Die doel van hierdie studie is om 'n bydrae te maak tot so 'n databasis. 2. Plant materiaal van die 10 kultivars is verkry van "n geenbank naby Potgietersrus in die Noord Transvaal (230 50'S), Suid-Afrika. Hierdie is 'n area met n subtropiese klimaat en oorwegende somer reënval. Die kultivars is gekarakteriseer volgens algemene hortologiese en veevoer eienskappe. Die kultivars se weerstand teen vier patogene wat uit kommersïele boorde in Suid- Afrika versamel is, is ook getoets. 3. AI die morfologies data is vergelyk met die genetiese data wat versamel is. Die resultate het aangedui dat morfologiese data, ongeag of dit hortologies, patologies of veekundig van aard is, onvoldoende is om die cultivars genoegsaam te karakteriseer, as dit nie in kombinasie met genetiese studies . gedoen word nie. 4. Die feit dat hoof indelings van die morfologies en patologiese dendrogramme nie korreleer met die AFLP dendrogram nie, is 'n bewys van lae korrelasies tussen die substel DNA verwant aan morfologies karakters, die substel DNA verwant aan patologie en die toevallige monster van totale genomiese DNA. Dit beklemtoon die onbetroubaarheid van die gebruik van slegs morfolgiese en patologiese parameters in seleksie. Om hierdie probleem op te los sal verdere karakterisering van hierdie kultivars in die verskillende verbouiingsgebiede in Suid-Afrika gedoen moet word, sodat die invloed van die omgewing op hierdie kultivars beter verstaan kan word. Karakterisering van hierdie kultivars met' n wyer hoeveelheid parameters, bv. ook koue bestandheid en weerstand ten opsigte van 'n wyer verskeidenheid patogene, kan die gebruik van morfologiese data vir seleksie ook meer betroubaar maak. 5. Dit is duidelik uit die literatuur dat O. ficus-indica 'n veelsydige gewas is, wat van groot waarde kan wees in onderontwikkelde en ontwikkelde lande vanweë sy vermoë om artede areas tot hulle volle potensiaal te benut. Die volle potensiaal van O. ficus-indica in Suid-Africa is nog nie ten volle benut nie, tog is dit duidelik uit hierdie studie dat die 10 kommersïele kultivars in Suid-Afrika goed met ander kultivars wat in die literatuur beskryf word, vergelyk.