Evaluation of reaction of drought tolerant wheat lines to stripe rust in adult plant and seedling plant stages.

rust caused by Puccinia striiformis f. sp. tritici (Pst) is the most important disease of wheat in many wheat growing areas in Iran. Evaluation of rust responses in selected preliminary, advanced and elite wheat lines prior to their release for widespread cultivation is very important in breeding program. Wheat materials were included of 198 selected Preliminary, advanced and elite wheat lines from drought project of Seed and Plant Improvement Institute. In relation to rust resistance studies at the adult plant stage in the field, each of the lines and susceptible check cultivars were grown on two one meter rows in yellow rust trap nurseries of Zarghan and Mashad. Artificial inoculations with rust isolates from mentioned areas (pathotypes 6E130A+, 134E22A+ in Zarghan and 2E2A+ in Mashad) were down for three times since late winter to early spring. Adult plant responses to stripe rust were recorded at three 7 to 10 days intervals after the disease was reached to 100S on the flag leaf of susceptible check Bolani. In addition a study was carried out to determine seedling reactions of these lines to stripe rust using pathotype 166E6A+ of Cereal Pathology Department of Seed and Plant Improvement Institute under greenhouse condition in Karaj. Seeds of the above lines and susceptible check were sown in small pots and inoculated with stripe rust at two leaf stage. Recording was accomplished after 17 days. The result showed that the majority of lines in each experiment had resistance reactions at both adult plant and seedling stages. In this regard a sum of 157 lines had different resistance reaction including Immune (0), resistant (R),moderately resistant (MR) and moderate (M), and the rest of lines showed to be moderately susceptible or susceptible at the adult plant stage in one or both sites. At the seedling test from a total of 104 lines examined, 75 lines had immune reaction and the remaining lines were susceptible (3+ or 3++). In conclusion lines with susceptible reaction at the seedling stage and resistance reaction R to 30MR at the adult plant stage are of first priority in selection for subsequent breeding programs. Besides among lines with resistance reaction at both stages, those that had R to 30MR resistance reaction at the adult plant stage are also recommendable for subsequent breeding programs.