Identification of drought tolerant genotypes in selected wheat genetic resources in the National Plant Gene-Bank of Iran

Exploiting advanced breeding materials to accelerate the development of new cultivars by breeders has created global concern about the narrow genetic basis of modern wheat cultivars. This is in contrary with the extensive genetic diversity stored in plant gene banks. Therefore, identifying landraces with useful characteristics would be of great value. Seventeen accessions of wheat collection of the National Plant Gene-Bank of Iran together with three check varieties, Kavir, Mahooti and Roshan, were evaluated in four different conditions; normal irrigation and irrigation ceased at different growth stages of; stem elongation (E1), heading (E2) and grain filling (E3) in 2007-2008 grown season. The highest grain yield belonged to genotypes 3, 2 and 15 in non-stress condition, 13, 11 and Mahooti in E1, 15, 11 and 1 in E2 and 2, 1 and 5 in E3. Genotypes 3 and 15 located at A region of Fernandez diagram in all three stress conditions and were superior to other genotypes, based on stress tolerance indices. Genotypes 4 and 11 had the lowest yield loss due to stress at grain filling as compared to non-stress condition and stress at heading, respectively. MP, GMP and STI were identified as the most favorable indices for all three stress conditions;E1, E2 and E3. Cluster analysis grouped the genotypes in 5, 3 and 4 groups at E1, E2 and E3 conditions, respectively. Results indicated that tolerant genotypes should be identified according to the growth stage at which the drought occurred.