Selection of sorghum [Sorghum bicolor (L.) Moench] genotypes for drought tolerance using physiological characterization

Abstract

Sorghum [Sorghum bicolor (L.) (Moench] genotypes are potential reservoir for genetic improvement towards various biotic and abiotic stresses. The genotypic differences were investigated among the thirty genotypes including a tolerant (B35) and susceptible (Co26) cultivar to moisture stress tolerance in field condition. In our study, the genetic variability parameters such as, phenotypic and genotypic coefficient of variation was higher for epicuticular wax (98.01) and leaf rolling (72.62), respectively. Likewise, higher heritability and expected genetic advance as per cent mean was reported for net photosynthetic rate (96.60) and leaf rolling (143.59), respectively. Correlation coefficient analysis found that most of the putative traits had significant association with grain yield viz., stay green score (r=0.80**), transpiration rate (0.67**), chlorophyll content (r=0.66**), relative water content (r=0.65**), early ground cover (0.58**), net photosynthetic rate (0.54**), root length (0.38*), epicuticular wax (0.30) and leaf rolling (0.10). Its genetic diversity was assessed through putative physiological trait expressions based on mean performance resulted in four clusters viz., I, II, III and IV consisting of 5, 12, 4 and 9 genotypes, respectively. Cluster I comprised superior genotypes along with tolerant cultivar. Further, principle component analysis revealed three components each explained by 47.45%, 15.83% and 12.18%, respectively of total variation based on putative physiological traits. Accordingly, biplot analysis revealed that four genotypes viz., DRT1026, ICSR24001, DRT1030 and DRT1019 showed superior performance for drought tolerance. The pattern of physiological responses and genetic diversity offers further opportunity for genetic resource conservation and utilization for genetic improvement of sorghum for drought tolerance.