In common with other grain legumes, the growth habit in horse gram is one of the domestication-driven adaptive traits. Horse gram exhibits determinate and indeterminate types of growth habits. Determinate genotypes have non-overlapping vegetative and reproductive phases combined with a compact growth habit which enables farmers to produce horse gram in intercropping and multiple cropping systems, a common practice for sustainable agriculture production. Also, synchronous flowering, and pod development and maturity of determinate genotypes enable mechanical harvesting. Empirical studies have indicated a greater grain yield potential of indeterminate compared to determinate genotypes. However, we hypothesize that indeterminate and determinate genotypes do not differ for their grain yield potential if they are in isogenic genetic backgrounds. To test this hypothesis, we compared eight pairs of near isogenic (NI) indeterminate and determinate genotypes for their grain yield potential during two rainy seasons in one location and one rainy season in another location. The eight pairs of NI determinate and indeterminate genotypes differed significantly in each of the three test environments. Indeterminate genotypes produced a greater pod (harvestable) and grain (marketable) yields than their determinate counterparts only in a few genetic backgrounds. These results thus support our hypothesis that determinate genotypes are comparable to indeterminate ones, if not better than the latter.

Preliminary studies were conducted using four varieties of potted cowpea (Ex-Luanda, Katuli 107. Vita 1, TVx66–2H) to determine plant response to injury to foliar and reproductive structures. Several levels of leaf loss were simulated at two plant growth stages; flowers were excised manually for 10. 15 and 20 consecutive days post-flowering; and pods were removed at several levels, 7–10 days after flowering. Similar tests were carried out during the short rains of Mbita Point Field Station (MPFS) and on a farmer's field at Kodiera, near Homa Bay, using two varieties—a local indeterminate dual purpose type (Ex-Luanda) and a determinate grain cultivar (TVu 1509). Defoliation significantly decreased plant weight and pod and grain production, but not branching and pod dimensions of potted plants. Flower and pod loss did not markedly lower plant weight, pod and seed production, and the effect on branching was negligible. The response of field plants was strongly influenced by crop variety and environment, notably agronomic practices and location. These results have implications for integrated pest management (IPM) which are explored in the context of increased grain legume production.