Concurrent effect of drought and heat stress in rice (

The present study was carried out to investigate the physio-biochemical and molecular responses of two rice genotypes (Noichi and N22) under drought, heat and combined drought/heat stress conditions. The antagonistic stomatal activity was found under the combined stress conditions; stomata were open under control and heat stress, conversely, stomata remained closed under drought and combined stress levels. Photosynthetic activity and chlorophyll content are decreased by the overproduction of reactive oxygen species and increased lipid peroxidation in both rice genotypes. To prevent oxidative damage, many antioxidant enzymes like catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) are produced in both genotypes under these conditions. Under the single stress conditions, CAT activity were increased in N22, whereas combined stress levels, SOD and APX activity were higher for both genotypes. Proline accumulation was also increased under single as well as combined stress conditions for both genotypes to combat stress injuries. Pollen viability was lost under all stress levels but severe loss was found under combined stress levels, which causes spikelet sterility leading to yield losses for both genotypes. As evident from transcript levels, Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-024-03980-1.