Production evaluation of Opuntia robusta and O.ficus-indica cultivars in the central Free State

[摘要] English: The search for appropriate plant species able to produce with sustainably in arid andsemi-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 differentcactus pear cultivers under a range of environmental conditions. This includes thecultivation for both fodder and fruit production. Cactus pear could be introduced withgreat success on land presently deemed marginal for other crops. A study was thereforeconducted to evaluate the production potential of ten cultivars of the green pad cactuspear species (Opuntia ficus-indicaï and one blue pad cultivar of O . robusta over threegrowing seasons (2001/02 to 2003/04). The cultivars of O. ficus-indica includedAlgerian, Gymno Carpo, Morado, Nudosa, Roedtan, Sicilian Indian fig, Tormentosa, VanAs, X28 and Zastron. The species O. 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 plotconsisted of 20 plants, of which 10 were used as data plants, planted in two rows. Duringthe study vegetative, reproductive and laboratory measurements were evaluated for thedifferent treatments and cultivars.It was evident from this study that young cactus pear plants could be killed by acombination of frequent successive nights of temperatures below the freezing point (aslow as -9°C) and water stress. Shortage of soil nutrients could also influence both fruitand fodder production in young cactus plants. Mechanical weeding near the cactus plantscould damage the shallow and widespread roots thus reducing the ability of plants to copewith harsh drought. Therefore, chemical control of weeds is encouraged.This limited study has revealed that Roedtan is the best cultivar for both fodder and fruitproduction while Morado is also ideal for production of both fodder and fruit. Otherpromising cultivars (although not as outstanding) for fodder production are Algerian,Gymno Carpo, Nudosa, Van As and Zastron. The same cultivars, except Zastron, canproduce promising results in fruit production. Monterey, Sicilian Indian fig, Tormentosaand X28 can produce satisfactory results in terms of fodder production. The samecultivars except Monterey can produce satisfactory results in terms of fruit production.The study has proved that Zastron and Monterey should be discouraged for fruitproduction. However, more in-depth research should be carried out to provide moreinformation about the cultivars in the different arid environmental conditions of southernAfrica.In the minimum descriptor list for Opuntia species for fruit production, only Tormentosaqualifies to be categorised as having very few seeds « 100), while most of the othercultivars have few seeds (101 - 200). The study has demonstrated that all other cultivarsexcept Monterey are easy to peel. It needs to be established by research if there is adifference between young and mature cactus pear cultivars in terms of number of seedsproduced per fruit. The limited information obtained from this study could benefit bothcommercial and subsistence farming communities living in drought threatened areas.

[发布机构] University of the Free State