Effects of timing of drought stress on phenology, yield and yield components of short-duration pigeonpea

Nine short-duration pigeonpea genotypes were given adequate soil moisture throughout growth or subjected to water stress during the late vegetative and flowering (stress 1), flowering and early pod development (stress 2), or podfill (stress 3) growth under field conditions. The stress 1 treatment had no significant effect on the time to flowering. No stress treatment affected maturity or inter-plant flowering synchronization. The interval from a newly opened flower to a mature pod was about 30 days for all genotypes, and was uncharged in plants that were recovering from stress 1 or undergoing stress 2. Seed yield was reduced to the greatest extent by stress 2 (by 37%) and not significantly affected by stress 3 for all genotypes, no consistent differences were found between determinate and indeterminate genotypes in the ability to maintain seed yield under both stress 1 and stress 2. The harvest index was significantly reduced (22%) by stress 2 but not be stress 1. However, under each soil moisture treatment, genotypic difference for seed yield were associated largely with differences in total dry matter production (TDM). For all genotypes the number of pods m(-2) was the only yield component significantly affected by the water stress treatments. The stability of other yield components should be fully exploited to improve the stability of seed yield under drought conditions (drought resistance). Possible characteristics which may improve the drought resistance of short-duration pigeonpea include the ability to maintain TDM, low flowering synchronization, small pod size with few seeds pod(-1), and large 100-seed mass.