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Selection of elite rice cultivars through backcross as well as based on quantitative genetics, and interaction of rice cultivars were evaluated by genetic index at the High Agricultural Technology Research Institute (HATRI) for Mekong Delta, Vietnam. A population was developed from a cross between OM10252 (high yielding variety and short duration from Cuu Long Delta Rice Research Institute (CLRRI) as female parent and Pokkali as male parent (a donor in many breeding programs and salinity tolerance related studies from Indian). Analysis of 95 individuals from the BC3F3 population of OM10252 /Pokkali// OM10252, the plant height trait, root length, dry weight of stem, dried weight of roots had the positive and high correlation with the survival time of rice plants at EC = 0 dS/m, 8 dS/m and 15 dS/m. The line BC3 F4-17 gave good survival at 4‰ condition in different areas. A final comment is that both field management and improved cultural practices were extremely important for sanity in rice. For generations, salt-tolerant lines will continue to grow and will be evaluated in the vegetative and growth stages, and included in breeding programs. [ABSTRACT FROM AUTHOR]

Information on genetic diversity among traditional varieties is critical in breeding programs as this influences parental selection in varietal development. A total of 100 traditional varieties in the genebank of the Cuu Long Delta Rice Research Institute (CLRRI), Vietnam, were used to explore this diversity using SSR markers. The study aims to evaluate the genetic diversity of traditional rice varieties and involves molecular diversity analysis using 55 polymorphic SSR markers revealed among the 100 varieties. The Vietnam varieties generated four clusters at 0.60 similarity coefficient. Some varieties with similar names were grouped into different clusters as molecular analysis showed that they were actually genetically different. The 100 landrace varieties collected were evaluated phenotypically. In the analysis of quantitative traits, the range of coefficients of variability was high. It varied from 94.38-80.3% (filled grain) to 60.02-5.63% (unfilled grain). This shows that these traits can be considered most stable as exemplified by their coefficients of variability. The highest values seen in unfilled grain indicate that this character is more affected by the environment and farmers' cultural management practices. The mean values of quantitative trait measurements were higher (78.75-139.75 cm). The highest values noted in yield (3.10-105.16 g) and survival (21-30 days) show good prospects to plant breeders. It has remained one of the major breeding objectives in developing rice varieties. Looking at agro-morphology, ANOVA showed highly significant differences among the 100 traditional rice varieties. The standardized Shannon-Weaver diversity indices for the quantitative morphological characters ranged from 0.68 to 0.95 with a mean of H' = 0.79. Cluster analysis using UPGMA grouped the 100 traditional varieties into 3major clusters. Varieties collected from the same site were grouped together in the same cluster. [ABSTRACT FROM AUTHOR]