Abstract
Chickpea being a winter season crop often experiences heat stress during reproductive phase. For chickpea production, terminal heat stress is one of the major constraints. Plants have built up numerous mechanisms to combat the heat stress. We considered the photosynthetic pigments for heat tolerance. Therefore, in order to investigate the heat tolerance in relation to photosynthetic pigments, a field trial was carried out having 4 contrasting genotypes namely BG 240 and JG 14 (relatively heat tolerant), SBD 377 (moderately tolerant) and ICC 1882 (relatively heat sensitive). Heat stress was imposed by altering the sowing date i.e. normal (18th November) and late sown (18th December). Under delayed sown condition, heat stress was faced by crop starting from flowering stage to crop maturity. Under heat stress condition, heat tolerant genotypes BG 240 and JG 14 maintained higher level of membrane stability, RWC (%), osmolytes, dry matter partitioning, grain yield, heat tolerance index and had higher values of zeaxanthin, quantum yield of PS II (Fv/Fm ratio), non-photochemical quenching (NPQ), photosynthetic rate, level of photosynthetic pigments (chlorophylls and carotenoids) and lower level of violaxanthin, and lipid peroxidation as compared to heat sensitive one (ICC 1882). In addition to this, Fv/Fm ratio and NPQ exhibited positive relationship with heat tolerance which suggested the involvement of xanthophyll cycle pigments in chickpea heat tolerance.