2025-06-01 GENETIC RESOURCES AND CROP EVOLUTION 2025 72(卷), 5(期), (6097-6110页)
Cowpea (Vigna unguiculata (L.) Walp.) is an important multipurpose crop cultivated in dry and semi-arid regions. However, high temperatures during cowpea's reproductive phase result in flower drop and poor pod and seed set. This highlights the importance of identifying germplasm for heat tolerance. We subjected 250 diverse cowpea genebank accessions to timely sowing (normal temperature) and late sowing (4-5 degrees C higher temperatures during flowering and pod development). Under the heat stress, accessions exhibited reduced flower formation, pod setting, seed count, and yield. The analysis of variance results indicated significant variation in traits due to genotypic, environmental and interaction effects. Genetic analysis identified traits viz. pods per plant, plant height, grain yield, and secondary branches (all with high phenotypic and genotypic coefficients of variation) as key traits for heat tolerance in cowpea rather than canopy temperature at pod development and chlorophyll content (both with low coefficients of variation). Cowpea accessions were found to achieve heat tolerance via different mechanisms. Nine accessions escaped heat stress by way of early maturity (15 days). Fifteen accessions displayed photo-thermo insensitivity even at temperatures exceeding 44 degrees C, while 10 accessions survived by maintaining cooler canopy temperatures. Accessions EC240920, IC488085 and IC488270 showed superior performance for multiple traits. Sixteen accessions had stable yields under both normal and heat-stressed conditions. Our study identified the heat stress associated traits for screening cowpea germplasm as well as shortlisted promising accessions. We expect that these will assist cowpea breeders to develop cultivars better adapted to high-temperature regimes.