Improvement of Drought Resistance in Rice.

The unpredictability of drought patterns and the inherent complexity of the physiological responses involved have made it difficult to characterize component traits required for improved performance, thus limiting crop improvement efforts to enhance drought resistance in rice. The various stress–response mechanisms and options to enhance plant survival under severe stress do not usually translate into yield stability under water deficit. Increased crop yield and water productivity require the optimization of the physiological processes involved in the critical stages of plant response to soil drying, water-use efficiency, and dehydration-avoidance mechanisms. New high-throughput phenotyping methodologies have been developed to allow fast and detailed evaluation of potential drought-resistant donors and the large number of lines identified by drought-breeding programs. Similarly, large collections of rice germplasm, including minicore sets, wild relatives, and mutant lines have been screened for drought-resistance traits. Genetic sources of drought resistance have now been identified for all major rice agroecosystems and some of the associated traits have been characterized. The identification and genetic mapping of major QTLs for performance under drought stress across environments are currently a major focus. This approach provides a powerful tool to dissect the genetic basis of drought resistance. If validated with accurate phenotyping and properly integrated in marker-assisted breeding programs, these approaches will accelerate the development of drought-resistant genotypes. This chapter reviews the recent progress and achievements in dissecting drought resistance in rice and presents future perspectives for the genetic enhancement of drought adaptation.