Salinity stress tolerance of advanced swamp rice breeding lines

Abstract

Problem of salinity stress often occurs on rice grown on tidal swamps, especially those located in estuaries near river mouths. Salinity stress can drastically reduce plant growth and yield. The use of varieties better adapted to saline swamplands would lessen the risk of yield reduction or crop failure. The salinity tolerance of 10 advanced swamp rice breeding lines during early plant vegetative growth was  reported their agronomic performances on a saline swampland. A greenhouse experiment was performed to grow the lines on a nutrient solution containing different concentrations of NaCl. Similarly, all these genotypes were subjected to field experiments on inland swampland and estuarine swampland. The mortality data on the greenhouse experiment during the first 7 days after transplanting (DAP) showed that the median lethal concentration of NaCl (LC50) ranged from  1963.28 ppm to 4863.44 ppm has placed UBPR 1, UBPR 3, UBPR 4, UBPR 6, and UBPR 8 as tolerant genotypes, UBPR 2, UBPR 7, UBPR 9, and UBPR 10 as medium tolerant genotypes, and UBPR 11 as susceptible genotype. However, as the plants reached 14 DAP the range of LC50 was reduced to between 1456.72 ppm and 3374.26 ppm, and accordingly no breeding lines could be deemed as tolerant genotype The water salinity of estuarine swampland reached 5865.23 ppm had resulted in a substantial reduction in the agronomic performances of all breeding lines. The grain yield of the breeding lines obtained from estuarine swampland was reduced between 25.8% and 52.9% when compared to those obtained from inland swampland, with the highest reduction found on UBPR 8. The current study provides new insight into the development of new rice varieties tolerant to salinity stress.