Genetic diversity for plant water relations, gaseous exchange, leaf anatomical characteristics and seed yield in cowpea under receding soil moisture

Abstract

Drought stress is the major constraint in cowpea grown on stored soil moisture conditions especially during the pod formation period. The long term sustainable and environmentally desirable solution is development of new varieties with drought tolerance. To generate information on the effect of receding soil moisture on physiological traits and yields would be helpful in identifying and developing drought-tolerant cowpea genotypes. A field experiment was conducted on 25 diverse genotypes of cowpea at CCS Haryana Agricultural University, Hisar. The genotypes were grouped on the basis of flowering initiation and the physiological observations were recorded during the flowering stage. Highly significant genotypic differences were detected between and within the group for physiological traits, biomass, yield attributes and seed yield. The early flowering genotypes (Group-I) showed lower leaf water potential (LWP), higher leaf water content (RWC), canopy temperature depression (CTD) and photosynthetic rate (PN) compared to medium (Group-II) and late (Group III) flowering genotypes. RWC and CTD were significantly associated with seed yield. RWC was also correlated with PN Therefore, the traits RWC and CTD, which are simple to measure, could be used for screening cowpea germplasm for drought tolerance.