Amelioration of heat stress during reproductive stage in rice by melatonin

Abstract

Melatonin is a low molecular weight hormone found in mammals and a natural bio-stimulating molecule in all living organisms from prokaryotes to eukaryotes. In plants melatonin plays an important role as a growth regulator and a stress buffering agent but its role under heat stress in rice reproductive stage remains undetermined. In the present study we have identified melatonin’s role to alleviate heat stress mediated damages to photosynthesis system and chlorophyll damage in two contrasting genotypes for heat stress tolerance. High temperature stress was given at anthesis and the treatment of melatonin was applied as foliar spray. We observed that melatonin treatment significantly increased chlorophyll content under heat stress compared to mock treated plants. Further, our studies on photosynthetic traits gave an insight to melatonin mediated improvements on photosynthesis rate across all the treatments but more significantly in the thermo-sensitive genotype. Improved photosynthesis rate and chlorophyll content might be due to direct antioxidant scavenging and improved antioxidative system. All these findings show that melatonin has a potential role to develop crop varieties with higher stress tolerance capacity.