Evaluation of Drought Resistance in some Iranian Landraces of Durum Wheat (Triticum turgidum)



Drought stress is considered as the most important environmental abiotic stress, affecting grain yield of crop plants especially in arid and semi arid regions. Increasing and utilization of the genetic diversity can be a useful strategy in breeding for drought resistance. In this study, twenty Iranian durum wheat landraces along with two check cultivars were evaluated in a randomized complete block design with three replications, under stress and under non-stress conditions, in 2005 in Karaj, Tehran. Lines showed significant differences for most of the traits examined in either stress or non-stress conditions except for the number of leaves. The highest reduction, in stress condition, was observed for spike weight, grain yield and as well as for the leaf relative water content. Correlation analysis indicated that in both conditions, yield components including number of spiklets per spike, seed weight, number of kernels per spike and spike weight as well as biological yield, harvest index and peduncle length, exhibited the highest positive correlation with grain yield. The stepwise regression showed that harvest index, biological yield, number of spiklets per spike and days to flowering could be used as desirable criteria for yield improvement under non-stress condition, whereas spike weight, number of grains per spike, harvest index and biological yield could be considered as useful criteria under stress conditions. Principle component analysis and biplot graph showed that Stress Tolerance Index (STI), Geometric Mean Productivity (GMP), Harmonic Mean (Harm), and Mean Productivity (MP) might represent the best indices for drought resistance selection. Based upon bi-plot graph, lines 9, 15 and 21 were found to be the most resistant, while lines 5, 6, 4 and 8, the most susceptible.