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 moist ure throughout growth or subjected to water stress during the late veg etative and flowering (stress 1), flowering and early pod development (stress 2), or podfill (stress 3) growth under field conditions. The s tress 1 treatment had no significant effect on the time to flowering. No stress treatment affected maturity or inter-plant flowering synchro nization. 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 reduc ed to the greatest extent by stress 2 (by 37%) and not significantly a ffected by stress 3 for all genotypes, no consistent differences were found between determinate and indeterminate genotypes in the ability t o maintain seed yield under both stress 1 and stress 2. The harvest in dex was significantly reduced (22%) by stress 2 but not be stress 1. H owever, under each soil moisture treatment, genotypic difference for s eed 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 treatm ents. The stability of other yield components should be fully exploite d to improve the stability of seed yield under drought conditions (dro ught resistance). Possible characteristics which may improve the droug ht resistance of short-duration pigeonpea include the ability to maint ain TDM, low flowering synchronization, small pod size with few seeds pod(-1), and large 100-seed mass.