Introduction of New Landrace Varieties Adapted to Drought Stress

Screening and introducing landrace varieties (as useful cultigens) is important for cultivation under abiotic stresses in temperate regions with low precipitations. To evaluate the response of wheat (Triticum aestivum L.) landraces to post-heading drought stress, two types of cultigens including commercial cultivars and landrace varieties were cultivated under drought stress and fully irrigated conditions in 2010/11 and 2011/12. Drought stress reduced grain yield by 22 and 19% compare to fully irrigated conditions in the first and second year respectively. Regression models indicated that genotypes with higher grain yield under fully irrigated had higher grain yield under drought conditions. Thousand- grain weight and harvest index strongly affected by drought stress although plant height and heading date were less affected. Under drought condition, the highest grain yield (5.8-8.1 ton ha-1) was found in the landrace varieties KC4557, KC4633, KC4542, KC4862, KC3891 and KC4551 in both years. Grain yield of Shiraz and Cross-Boolani were 4.7 and 5.5 ton ha-1 respectively. Significant correlations of grain yield in fully irrigated (Yp) and drought (Ys) conditions with the indices of mean productivity (MP) and stress tolerance index (STI) support the idea that these indices are able to discriminate genotypic differences under drought conditions. Heading was not significantly correlated with grain yield. Therefore, selection for earliness does not affect grain yield under drought stress. Analysis of principal components indicated that the landrace varieties numbers KC4557 and KC4551 in 2010/11 and KC4633, KC4537, KC4862 and KC3891 in 2011/12 had higher grain yield under drought conditions. Results showed that landrace varieties had better performance than commercial cultivars under drought and KC4557, KC4633, KC4542, KC4862, KC3891 and KC4551 were more tolerant to drought conditions.