Deploying Stress Tolerant Rice Varieties Helps Farmers Cope with Climate Change Adversities

Floods, drought and salinity are major abiotic stresses constraining rice production in over 40 million hectares of rainfed lowlands in Asia, and their effects are worsening with climate changes, causing warmer temperatures, sea level rise and unpredictable rainfall patterns. This is reflected in lower and unstable productivity, leading to severer poverty and food insecurity. Efforts are needed to develop “climate ready” crops to cope with these adversities and to meet the increasing global demand for food. Salinity limits rice productivity in both irrigated and rainfed areas, causing low yields often below 2 t ha^-1. Numerous tolerant varieties were commercializied in recent years, with substantial yield advantges in saline areas. QTLs associated with tolerance were identified and are being combined in new varieties for higher tolerance. Both partial (stagnant, SF, 25-50 cm) and compete (submergence) floods can severely damage rice. Traditional varieties are still prevailing in affected areas, with low yields and poor quality. SF tolerant genotypes with higher yields were recently developed and mapping populations are being analyzed to identify QTLs associated with tolerance. Submergence occurs frequently and causes serious yield losses. The discovery and cloning of the SUB1 QTL helped in breeding varieties that tolerate submergence for 2 weeks, with no undesirable consequences. SUB1 effectiveness was validated in farmers’ fields with significant yield advantages. Numerous Sub1 varieties were commercialized and are reaching millions of farmers in Asia. SUB1 is being combined with tolerances of drought and salinity to provide resilient varieties for coping with climate changes.