Genetic diversity of sorghum [Sorghum bicolor (L.)] germplasm for drought tolerance

Abstract

Drought is a major cause which affects production and productivity of sorghum. Sorghum drought is associated with pre and post flowering stages. Stay-green is the important drought tolerant trait which is associated with post flowering stage. One hundred accessions of sorghum were sown in two different situations in RBD with two replications in Coimbatore, i.e. one with complete irrigation till physical maturity and another with imposed moisture stress from flowering to maturity. Genotype B35 was used as drought resistant check and variety CO26 as drought susceptible check. Significant variation was found on stress indicators like relative water content (RWC), SPAD chlorophyll and stay-green traits. The drought stress indices also showed significant variation which indicated selection of drought tolerance may involve either high yield potential or stable yield under water deficit condition. RWC and SPAD chlorophyll had a positive association with grain yield. Negative association with stay-green indicated RWC, SPAD chlorophyll and staygreen as important for selection under drought stress condition. Cluster analysis was performed based on physiological expression of stay-green trait. In cluster analysis tolerant genotypes and susceptible genotypes clustered separately, different clusters given an opportunity to select drought tolerant genotypes which can be used as donors for hybridization programme for drought tolerance.