Screening for drought tolerance and diversity analysis of Bangladeshi rice germplasms using morphophysiology and molecular markers

Drought is one of the significant environmental stresses which remarkably reduces crop growth and productivity that ultimately impacts on yield of the crop and thereby reduces the national target of food production throughout the world every year. Therefore, crop genotypes with a tendency of drought tolerance and higher yield, immediately need to be identified to accelerate the breeding effort. In this study, a total of 110 rice genotypes were screened for drought tolerance using Polyethylene Glycol (PEG-6000) treatment at the seedling stage in the growth chamber and water withholding treatment at the vegetative stage in the field. Data were scored and analyzed with a standard evaluation system (SES) for drought tolerance. Among the 110 genotypes, 13 were identified as tolerant, and seven as moderately tolerant to drought stress. For drought control, BRRI Dhan-56 was used as check. The result of the drought tolerance degree (DTD) at the vegetative stage revealed the highest DTD value in Kalara (0.908). Further, screening with drought-linked SSR markers (RM105, RM219, RM328, and RM332) indicated that the RM322 marker identified 14 genotypes that have similar banding patterns with BRRI Dhan-56. The remaining three markers identified 20 genotypes that have similar banding patterns with check variety. The cluster analysis by UPGMA showed that the genotypes Gojja and Payjam (at control condition), as well as Ranashail and Mokbul (at stress condition) are more closely interconnected, but they are distantly related with Kolom, BRRI Dhan-56, and Varat payjam. These tolerant genotypes identified in this study could be used as parents in breeding programs to develop improved drought tolerant rice varieties.