Effects of drought on yield and yield components of two contrasting growth habits of common beans (Phaseolus vulgaris L.)

Common bean is grown by smallholder farmers in Malawi who produce low yield due to drought constrains. Two experiments comprising of two different bean growth habits (IIa and IVa) were conducted at Chitedze Research Station in Malawi, to assess eleven common bean genotypes for yield and yield components under drought conditions. Drought reduced significantly number of pods plant-1, number of seeds pod-1 and consequently seed yield in both growth habits. Within growth habit IIa, the most productive genotype was BCB 2, that gave highest yield in both irrigated and drought stress conditions, also presented a higher yield percentage reduction (51.13%) after Sugar 131 (53.11%) implying highest drought susceptibility.  On the other hand, VTTT 923/10-3 (growth habit IIa) had the highest drought tolerance (32.40%). Under growth habit IVa, genotype MAC 109 was found to be the most drought tolerant (31.43%) under drought and 12D/2 highest drought susceptibility (50.92%). The results suggest that selection for genotypes with higher number of pods plant-1, number of seeds pod-1 and low yield percentage reduction might improve grain yield under drought stressed condition. Key words: Phaseolus vulgaris L., drought, growth habits, yield components.