Drought responses in rice (Oryza sativa L.): An integrated review of morphological, physiological, biochemical, phenological and genetic perspectives
Rice (Oryza sativa L.) production is severely affected by drought, which reduces yield, growth and physiological functions in various environments. This review integrates the morphological, physiological, biochemical, phenological and genetic responses of rice to drought, focusing on both common and environment-specific responses. Rice plants respond to water deficit by reducing leaf area and stomatal opening and modifying osmotic potential; roots may deepen or alter their architecture and flowering time may be delayed as an escape mechanism. Biochemically, osmolytes, antioxidants and hormones, especially abscisic acid (ABA), are key players in stress tolerance. Genetic mapping has identified several quantitative trait loci (QTLs) and candidate genes associated with root architecture, osmotic adjustment and flowering time, while transcriptomic studies have revealed the regulatory mechanisms underlying these traits under drought conditions. However, several challenges remain, including the lack of root phenotyping under field conditions, the instability of QTL effects across environments and the limited translation of pot-based findings to field performance. Integrated approaches that involve high-throughput field phenotyping, multi-environment trials to assess genotype × environment interactions and better integration of genomics with physiological traits across a variety of genetic backgrounds will be essential for future advances. These integrated approaches are pivotal in bridging the gap between field performance and the underlying physiological and molecular mechanisms, thereby facilitating the development of drought-resilient rice cultivars.