Drought's physiological footprint: implications for crop improvement in rice.

Rice, a staple food for significant percent of the world's population, is increasingly vulnerable to drought stress, threatening global food security. This review synthesizes current knowledge on drought's physiological impact on rice, highlighting key mechanisms, responses, and adaptations. Drought stress alters rice physiology at various stages, from seed germination to grain filling, affecting yield, quality, and nutrient content. Drought tolerance in rice is influenced by physiological traits such as root architecture and depth, stomatal regulation and water use efficiency, Osmo-protectants and antioxidant defences, hormone signalling and stress response pathways. Genetic diversity and molecular breeding have enhanced drought resilience in rice, with key genes and quantitative trait loci (QTLs) controlling drought tolerance identified, enabling marker-assisted selection and genetic engineering. Despite progress, challenges persist, including limited understanding of drought's impact on rice physiology under field conditions, inefficient screening methods for drought tolerance, and insufficient attention to drought's effects on rice quality and nutritional content. To address these gaps, integrating physiology, genetics, and agronomy for holistic drought mitigation strategies is crucial. Developing high-throughput phenotyping tools for drought tolerance screening and investigating drought's impact on rice grain quality and nutritional content are essential. This review provides a comprehensive framework for understanding drought's physiological footprint in rice and guiding future research toward improving drought tolerance and resilience.