Development of tolerant rice varieties for stress-prone ecosystems in the coastal deltas of Indonesia

Large areas of lowlands within tidal deltas have been reclaimed for crop production in Indonesia. However, major production constraints such as floods, seawater intrusion from tidal rivers, and adverse soils remain a significant problem, resulting in low rice yields (2-3 t ha−1) and production systems that are prone to risk. This review describes the recent progress in technology development, to address multiple abiotic stresses through the genetic improvement of rice. During the last 15 years, rice breeding programs and germplasm evaluation systems for coastal deltas have been revitalized. Local landraces, modern varieties and elite stress-tolerant genotypes were screened and physiological response to the stress and agronomic performance of promising genotypes were characterized. These efforts resulted in the release of the first series of flood- and salinity-tolerant varieties for lowlands in Indonesia. On-farm trials with these varieties demonstrated yield advantages of up to 125%, over popular varieties currently used by farmers in the marginal lowlands. Some of these varieties made an impact; Ciherang-Sub1, a submergence-tolerant variety near-isogenic of Indonesia's popular variety (Ciherang), occupied over 430,000 ha of rice lowlands within four years of its release in 2012. There are large “exploitable yield gaps” between the attainable farm yield and mean farm yield, and appropriate crop and natural resource management guidelines for the new rice varieties are being developed. These achievements highlight opportunities for sustainable development in unfavorable rice environments of coastal deltas and are relevant to other areas in South and Southeast Asia.