Assessment of adaptability of recently released salt tolerant rice varieties in coastal regions of South Bangladesh

Abstract

Productivity of rice is adversely affected by salinity and water logging stresses in coastal zones, and affected areas are progressively expanding as consequences of climate change and overexploitation of natural resources to meet the needs of increasing populations. Several varieties were developed and commercialized in this region in recent years, including some salt and stagnant flood (SF, medium deep, 25–50cm water depth) tolerant varieties. However, suitability of these varieties based on adaptation to local conditions across the region and farmers’ preferences have not been sufficiently evaluated. Genotype by environment analysis leads to identification of varieties with stable performance, or suitability to specific regions. Two frequently used statistical analyses are additive main effects and multiplicative interaction (AMMI); and the genotype main effects and genotype×environment interaction effects (GGE). These models were used in this study to identify stable rice varieties for the wet and dry seasons in South Bangladesh. Experiments were conducted at six sites over four years (2010–2013) in coastal Bangladesh, using eight and five varieties for wet and dry season, respectively. The trials were laid in a randomized complete block design (RCBD) with three replications. Genotypic contribution was much higher than the environmental effect on grain yield in the wet season, while the environmental contribution was much higher than genotypic effect during the dry season. SF stress affected yield of wet season rice; but in the dry season, salinity stress had major effect on grain yield. The variety BRRI dhan54 was identified as the most suitable genotype with wider adaptability in the region during the wet season, followed by BRRI dhan40 and BRRI dhan53, while BRRI dhan47 was the most stable variety followed by BRRI dhan61 and BINA dhan8 for the dry season across all sites. However, when these varieties were evaluated based on farmers’ preferences in participatory varietal selection, BRRI dhan53; a short duration variety with medium slender grains was the most preferred, followed by BRRI dhan54 and BRRI dhan40 for wet season, and in the dry season BRRI dhan47 was the most popular variety followed by BRRI dhan61, which agreed with ranking based on yield. Modern varieties were far superior over traditional varieties based on grain yield and farmers’ preferences, and should be targeted for large-scale seed production and dissemination.