Evaluation of Grain Yield of Cultivars and Promising Lines of Grain Sorghum [Sorghum bicolor (L.) Moench] Using of Drought Tolerance Indices

To evaluate drought tolerance in cultivars and promising lines of grain sorghum, an experiment was conducted as split-plot on randomized complete block design with three replications at experimental field of Seed and Plant Improvement Institute, Karaj, Iran in 2013 and 2014. Irrigation treatments were considered the main plot at three levels: irrigation after 60 mm evaporation from the surface evaporation pan (normal irrigation), normal irrigation till flowering and then irrigation after 120 mm evaporation (mild water stress), and water withholding after flowering (severe water stress). Were considered as main plot and five genotypes including cultivars Kimiya and Sepideh and promising lines KGS15, KGS23 and KGS32 as subplot. The results of combined analysis of variance showed that fresh fodder, biological yield and grain yield in irrigation treatments and genotypes for all traits had significant differences at 1 level of probability. Based on Stress Tolerance Index (STI) and Geometric Mean Productivity (GMP) indices, KGS23 line and Kimiya cultivar had higher grain yield than mean in all irrigation treatments. These genotypes had also the highest STI and located at zone of high yield potential and low sensitivity to drought in the biplot. Results of biplot analysis and correlation between drought tolerant indices and Ys and Yp showed that STI, GMP and MP were the best indices for selection of the suitable genotypes in drought stress conditions.