THE EFFECT OF PRUNING AND TRAINING ON THE YIELD OF TOMATO CULTIVARS GROWN FOR EXPORT IN THE SUDAN
Investigations were initiated with the objective of determining which tomato cultivars were most suitable for export and the establishment of optimum cultural practices. Additionally, the effects of pruning and training were to be related to the yield, quality and availability of tomatoes suitable for export at periods of high demand.
Several workers have examined the practices of pruning and training or staking tomatoes, but their results and conclusions have sometimes been conflicting. Currence (1941), Magruder (1924), Strijdom (1955), Thompson (1934) have indicated that pruning tends to increase average fruit weight, to promote earliness and to reduce total yield.
In contrast to these observations, Deonier et al (1944) showed that greater yields were obtained from staked and pruned tomatoes when compared with staked and non-pruned or non-staked and non-pruned tomato plants. Campbell (1961) indicated that neither staking nor pruning were economic methods of growing tomatoes. Chapman and Acland (1965) drew attention to the fact that Campbell's results were related to the use of only one plant population density, while other workers, Deonier et al (1944), Hawthorn (1939) and Thompson (1934) designed their experiments in such a way that the separation of effects due to population density and pruning was not possible.
Chapman and Acland reported a significant increase in yield with increasing population densities and confirmed that a reduction in yield was obtained from staked and pruned treatments. Jackson (1953) studied the effects of pruning on the yield of eleven tomato cultivars. He indicated that seven cultivars produced greater yields when pruned and staked, while four showed reduced yields with pruning and staking. Huxley (1962) showed that the yields of staked and pruned tomatoes were much lower than those of plants allowed to develop their natural habit.
Abdel-Al (1962) showed that defoliation increased earliness and leaf efficiency, but decreased the percentage of fruits affected by "Blossom End Rot" and he suggested breeding plants with sparse foliage. Wurster and Nganga (1970) indicated that 'Moneymaker' out-yielded all other cultivars and they showed that significantly greater total yields were obtained from bush grown plants than from either the pruned and staked or the