Rice Responses to Water Limiting Conditions: Improving Stress Management by Exploiting Genetics and Physiological Processes

Water-limiting conditions can severely affect rice yield. Therefore, increasing plant toleranceto water stress is a priority for many rice breeding programs. However, improving rice toleranceto this abiotic stress comes with several complications related to the seeding practices, the adoptedwater management system and the growth stage where water stress occurs. For this reason, it ischallenging to outline single ideotypes showing traits suitable for overcoming drought at differenttimes during the life cycle of rice in diverse cropping ecosystems. The current knowledge of genomicsand biochemicals can contribute to drawing rice ideotypes flexible towards diverse water availabilityconditions. Traits identified in accessions of the wild ancestor of cultivated rice, as well as other wildrice species, in Oryza glaberrima and weedy rice were demonstrated to confer enhanced tolerance towater stress, while screenings of cultivated rice germplasms identified several genes/loci improvingwater stress resistance. New frontiers are represented by the dissection of the epigenetic control ofstress tolerance and the implementation of the contribution of favorable microbiota. Innovative breedingtechnologies, whose feasibility is related to advancements in genomic analyses, are contributingto enhancing the knowledge-based development of water stress-tolerant rice varieties.