Bioregulators application improved heat tolerance and yield in chickpea (Cicer arietinum L.) by modulating zeaxanthin cycle

Abstract

Chickpea is sensitive to heat stress and generally experiences high temperature during reproductive phase. Therefore, terminal heat stress is key constraints for its production. Exogenous application of bioregulators is an option to improve heat tolerance and yield. Therefore, an experiment was carried out using two contrasting Desi type (JG 14) and Kabuli type (Pusa 1108) chickpea varieties with an objective to interlink bioregulators induced heat tolerance with zeaxanthin pigments cycle. Experiment was comprising two main treatments i.e. Normal (18th November) and late (20th December) sown conditions for exposing the crop to high temperature and four sub-treatments (Foliar application of bioregulators viz ABA (10 ppm), BA (40 ppm), SA (100 ppm), thiourea (1000 ppm) and water spray (as control) prior to flowering. Under high temperature condition, reduction in leaf photosynthesis, photosynthetic pigments, chlorophyll fluorescence parameters, yield and its attributes was recorded. Foliar application of bioregulators augmented the grain yield by improving the photosynthetic rate (PN), photosynthetic pigments including zeaxanthin, maximum quantum yield of PS II (Fv/Fm), non-photochemical quenching, heat tolerance index, yield attributes and reducing the level of violaxanthin and heat susceptibility index over the control (water) under late sown condition which in turn suggested that bioregulators induced the heat tolerance by activating operation of zeaxanthin pigments cycle in chickpea. Moreover, Kabuli chickpea variety responded better to bioregulators than Desi type particularly under heat stress condition.