Maturity, Biomass Partitioning and Growth Response Indices in Cowpea (Vigna unguiculata L.) under Water Stress

Water stress is the major abiotic constraint of cowpea production. The development of cowpea genotypes resilient to water stress is a practical approach to ameliorate the negative effects of water stress on the productivity. In the present study, a set of 20 genotypes of cowpea including 19 landraces collected from different areas of the Kashmir valley and one released variety viz, Shalimar Cowpea-1 released by SKUAST-Kashmir as check were evaluated under well watered and water stressed conditions.

Days to flowering and maturity did not undergo substantial changes between irrigated and water stressed treatments, however, pods partitioning index suffered largest decrease under stress (16.10 per cent) followed by plant height (12.27 per cent).

Among growth response indices, days to seed fill (DSF) was positively correlated with seed yield only under well watered conditions, while as rest all indices biomass growth rate (BGR), seed growth rate (SGR), Economic growth rate (EGR) and relative sink strength) RSS were positively correlated with seed yield under both water stressed and well watered conditions.

Highest values of correlation of indices with seed yield under water stressed and well watered conditions were recorded for EGR (r = 0.999 and 0.998 respectively) followed by SGR (r = 0.967 and 0.955 respectively) and BGR (r = 0.700 and 0.854 respectively), while as RSS had significant correlation with seed yield under water stress only.