Major Constraints for Global Rice Production: Changing Climate, Abiotic and Biotic Stresses

Abstract

Rice (Oryza sativa L.) is among major cereals that show significant susceptibility to a number of abiotic stresses. Environmental constraints inhibit relevant physiological and biochemical indices that, in turn, determine grain yield in rice. Heat stress induces significant changes in metabolic profiling in flag leaves and developing seeds that reduces grain yield and quality in rice. The grain yield in rice is also impeded as a result of salinity, drought, and heavy metal stress. The literature shows that rice plants growing in the environment with combined heat and drought stress show lesser spikelet fertility. The decrease in plant growth and productivity is the consequence of inhibited ions homeostasis, photosynthesis, the efficiency of both photosystems alongside the enhanced generation of reactive oxygen species, and loss of membrane integrity measured in the form of accumulation of malondialdehyde contents. Moreover, changes in secondary metabolites accumulation and disturbed ions homeostasis under stressful conditions also reduce growth and productivity of rice. The defense mechanisms manifested by rice entail osmotic adjustment, stimulated activities of antioxidant enzymes along with enhanced production of non-enzymatic antioxidant compounds. In this chapter, we have discussed the negative impact of abiotic and biotic stresses on key physiochemical processes. The defense responses of rice to different environmental constraints are discussed at length.