Masters Degrees (Soil, Crop and Climate Sciences)

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Browsing Masters Degrees (Soil, Crop and Climate Sciences) by Advisor "Engelbrecht, Gesine M."

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    The influence of environmental factors on spineless cactus pear (Opuntia spp.) fruit yield in Limpopo Province, South Africa
    (University of the Free State, 2007-11) Potgieter, Johannes Petrus; Walker, Sue; Engelbrecht, Gesine M.
    English: Limited information is available on the response of local cactus pear cultivars to environmental factors that influence fruit yield. Eleven cultivars were evaluated in three diverse agro-climatic areas over seven production seasons in the Limpopo Province to assess their environmental adaptability. Significant differences between cultivars, areas and production years for five fruit yield components were evident. A strong genotype by environment interaction was observed, although some cultivar characteristics were genetically controlled. The most suitable production area is the cool mid-altitude area of Limpopo Province. Cultivars that can be recommended for fresh fruit production are: “Algerian”, “American Giant”, “Gymno Carpo”, “Malta”, “Morado”, “Nudosa” and “Zastron”. Fruit yield was significantly influenced by minimum temperature and plant macro nutrients. Soil phosphorus levels above 20 mg kg-1 and applied nitrogen higher than 100 kg ha-1 year-1 had a positive effect on fruit yield. Soil pH did not influence the fruit yield of the cultivars tested. None of the cultivars tested had a winter chilling requirement to become fertile. Vegetative growth was stimulated by increased solar radiation. Cactus pear plants can be considered to be fully mature from the fifth year onwards. Environmental adaptability is related to species differences rather than plant morphological differences. Plant growth habit changed markedly in different environments. To obtain high fruit yields, it is important to match a cultivar with prevailing environmental conditions of the area. Fruit yield in cactus pear is a function of the number of fertile cladodes, the number of fruit set, the number of fruit left after thinning and individual fruit mass. Research into orchard practices, in particular pruning, and evaluation of the existing cactus pear germplasm should receive attention. As a “new” cultivated fruit crop it offers real solutions towards mitigation of the effects of drought in arid and semi-arid parts of Limpopo Province.