Evaluation of 14 winter bread wheat genotypes in normal irrigation and stress conditions after anthesis stage
In order to evaluate wheat genotypes in terms of tolerance to drought stress after anthesis stage, some experiments were conducted using 14 winter bread wheat genotypes in a randomized complete block design with three replications in normal irrigation and drought stress conditions at the research stations of Ardabil, Bilesavar and Namin in the 2009 to 2010 cropping years. Evaluation of genotypes for drought tolerance was performed by indices including stress tolerance index (STI), stress sensitivity (SSI), tolerance (TOL), mean proficiency (MP), the geometric mean (GMP) and the mean rating (mean R), and also by the earlier mentioned indices for all the genotypes and relevant biplot drawing. The results of the combined variance analysis of grain yield showed that the effect of location was meaningful under normal irrigation conditions; this was obtained under drought stress conditions. The interaction of genotype with location in normal irrigation conditions was meaningful in a probability level of 5, while it was not meaningful under drought stress. The effect of genotypes was not meaningful under normal irrigation conditions, while it is significant under drought stress. Considering indices correlation with yields of two normal and stress conditions, indices MP and STI were identified as the best indices. Using biplot graphic method, comparison of indices amounts and mean rating of indices for each genotype observation of placing position of genotypes in the biplot of genotypes 6, 10, 7 and 13 were identified as tolerant genotypes. However, genotype 14 was identified as the most sensitive genotype to end drought stress.
Key words: Bread wheat, drought stress, grain yield, drought tolerance and drought sensitive indices, biplot.