Effects of Timing of Drought Stress on Abscission and Dry Matter Partitioning of Short‐duration Pigeonpea

Abstract

AbstractShoot dry mass partitioning and cumulative abscission of leaf, flowers and pods were determined for nine short‐duration pigeonpea genotypes grown with adequate soil moisture throughout growth (control), or subjected to water stress during the late vegetative and flowering (stress 1), flowering and early pod development (stress 2), or pod fill (stress 3) growth stages. The total cumulative dry mass of abscised plant parts was lower for determinate genotypes, but it increased to a greater extent under water stress than that for indeterminate genotypes, with stress 2 having the greatest and stress 3 die least effects. The dry mass contribution of pods to total abscission was ≤ 5%, and not signiflcantiy affected by water stress, while the contribution of leaves increased and mat of flowers decreased. Stress 3 had no significant effects on abscission dry mass totals or components. Reduction in shoot dry mass under water stress was most pronounced for genotypes in die early pod development stage, and the dry mass contribution of leaves generally decreased and that of pods increased under stress 1 and stress 2. With similar abscission levels, the shoot dry mass of genotype ICPL 151, was similar to, or greater than, that of hybrid ICPH 9, under stress 1 and stress 2, and the contribution of pods to shoot dry mass was lower for hybrid ICPH 9 under both stress treatments. Genotypic differences in drought resistance were likely due to differences in the leaf area maintenance during, and in the recovery of dry mass and pod production following, water stress periods.