Recent Approaches in Breeding for Salt Tolerance in Rice in Bangladesh

Salinity is one of the most important abiotic stresses which limit agricultural productivity and pose threats to food security in Bangladesh as rice is the main staple food but sensitive to salt stress. As of now, farmers grow local varieties in the southern coastal region during T. Aman (wet) season which is moderately tolerant to salt stress with low yielding potential, and large areas remain fallow during boro (dry) season because of high salinity (12–16 dSm−1). Breeding high yielding salt-tolerant rice is a sustainable way to develop varieties for this highly saline zone and brings these highly saline areas under rice cultivation that leads to maintaining food security for achieving the Sustainable Development Goals (SDGs). The physiological, genetic, and molecular pathways of salt tolerance have extensively been studied, but these pathways need to be addressed from the salt tolerance enhancement perspective, and these should appropriately be combined with the breeding approaches. There is an adequate variation for salt tolerance in rice germplasm, and salt tolerance is a complex quantitative trait. Hence, attempts are being focused on using this variation to develop high yielding salt-tolerant varieties through applying holistic approaches of breeding including conventional, molecular, and modern breeding methods. Understanding the gene action for salt tolerance in rice is important for use in the future breeding program. Selection for salinity tolerance with high and low heritable traits may be made in the early and later generations, respectively. A number of QTLs and gene-based markers for salt tolerance have been reported which have an immense potential for use during genomic assisted breeding. Seventeen salt-tolerant rice varieties have been developed and released in Bangladesh, and a series of salt-tolerant breeding lines were developed based on region-specific product profiles for the target region of Bangladesh.