Determination of suitable indices for evaluation of drought tolerance in bread wheat double-haploid lines (Triticum aestivum L.)

In order to evaluate the drought tolerance of wheat cultivars and identification of tolerant and sensitive genotypes based on sensitivity and tension tolerance indices, a research was carried out under two conditions of water and drought tension in the form of a simple lattice design of 7 in 7 (including 7 incomplete blocks) and with 2 replications for 49 wheat genotypes including 45 double haploid lines of wheat (double haploid) with parents and two local cultivars (Gascogen and Pishtaz) as control in Shahrood in 2015-16 cropping year. The results of correlation between drought tolerance indices and grain yield under tension and non-tension conditions showed that there was a positive and significant correlation between Mean Productivity (MP), Harmonic Mean (HM), Geometric Mean Productivity (GMP) indices and Stress Tolerance Index (STI) with grain yield in both environmental conditions and were identified as suitable indicators for selecting high yielding cultivars in both tension and non-tension conditions. Among these indicators, the STI index was determined as the best indicator. The maximum amount of the above indices also belonged to the double haploid line 43 (DH43). Main components analysis based on seven indices of drought tolerance and grain yield in two conditions without tension and tension showed that the main component of the first, 68.15 percent and the main component of the second, 31.39 percent justify the variation of the initial data and thus, these two main components described a total of 99.5 5 percent of the total variation. By plotting the bi plot chart, it was determined that DH43, DH22, DH89, DH19 and DH13 double haploid lines were the most tolerant lines to drought tension among genotypes studied. The results of cluster analysis also corresponded to the results of the analysis of the principle components and the bi plot charts.