Characterization of High Yielding and Drought Tolerant RILs Identified from Wheat Cross WL711 x C306 RIL Mapping Population using Drought Susceptibility Index (DSI) as Selection Criteria

Wheat cultivars WL711 and C306 were shown to be drought susceptible and drought tolerant, respectively, in an earlier study. These two cultivars were crossed to obtain a RIL population comprising 206 RILs. The parents and the RIL mapping population was tested for drought tolerance via field trials conducted at Delhi from 2007 to 2010. Water stress was created by withholding irrigation. Phenotyping of the RIL population was done for phenology, yield and yield components under irrigated (Irr) and water stress (WS) treatments. The range of days to flowering in the RIL population was 78–98 and 74–96 days after sowing (DAS) under Irr and WS conditions, respectively. The range of grain yield, biomass, harvest index, 1000 grain weight, grain number in the RIL population was 335.1–720.0g/m², 1316-2413g/m², 22.3–58.6%, 24.0–45.1g, 9497-22763/m² and 219.2–568.1 g/m², 992-1759g/m², 17.3–54.8%, 23.1–39.7g, 8807-17509/m² under Irr and WS conditions respectively. Analysis of variance revealed significant interaction between genotypes and treatment for all the traits except 1000-grain weight and harvest index. Drought Susceptibility Index (DSI) was used as criteria for drought tolerance. DSI of yield and yield components showed considerable variation and transgressive segregation in the RIL population. Based on DSI of yield and yield components of the medium to late flowering RILs, 8 RILs were identified for combining yield higher than C306 with yield stability. These RILs maintained better water relations and tougher membranes under WS treatment, like C306.