Multivariate analysis of genetic divergence of genotypes of rice under salt stress during the vegetative phase

Soil salinity is a limiting factor for rice cultivation, especially in the early stages of development and the flowering period. The use of sources of poor quality water for irrigation results in the accumulation of salts in the soil, causing major toxicity in culture. A solution to the problem would be the introduction of varieties with tolerance to high salinity. Hus the aim of this work is to evaluate genetic divergence among rice genotypes, aiming at the selection of genotypes tolerant to salinity during the vegetative phase. Seeds of 10 rice genotypes were grown in vitro on MS medium supplemented with 0 and 136 mM NaCl. After 21 days, six morphological characters were evaluated and the results subjected to multivariate analysis. The methods of Tocher, based on Mahalanobis distance, and graphic dispersion of canonic variables followed the same pattern of clustering structure, forming six groups. The characteristic of shoot fresh weight was the largest contributor to the genetic dissimilarity between genotypes by the method of Singh, while the other two canonic variables were sufficient to account for 91.27% of observed variation. Under the experimental conditions tested, the genotypes showed different degrees of salinity tolerance, while Colossus BRS, BRS Bojuru and BR IRGA 410, belonging to the groups three and four, were those who were more tolerant genotype and Moti, belonging to two what was more sensitive to salt stress.