ارزیابی مقاومت ارقام گندم در دست معرفی دیم کشور نسبت به بیماری زنگ زرد در شرایط گلخانه ای و مزرعه ای با استفاده از محاسبه سطح زیر منحنی پیشرفت بیماری ‭(AUDPC )‬

‭In the present investigation, resistance of 16 bread wheat candidate lines for release from Dryland Agricultural Research Institute (DARI) were evaluated to yellow rust for two years in greenhouse and field conditions. Wheat entries were evaluated at adult-plant stage in field (under artificial epidemics of the disease in eight locations) and at seedling stage in greenhouse to identify adult-plant and seedling resistances respectively. Field tests were conducted in a Randomized Complete Block Design (RCBD) with three replications. Wheat entries were planted in November 2000 (first year) and 2001 (second year), at the rate of 10‬ص ‭15 g of seed in two 1 m long rows and spaced 30cm apart. A susceptible cultivar (Bolani) was planted in a few rows as borders of the nurseries. Anificial inoculation of the nurseries was done four times in a period of two months starting at tillering stage using the relevant race ofeach location. The infection type (IT) and the percentage leaf area affected of each entry was evaluated when the disease started to develop on susceptible check. and was continued by intervals 7-10 days until wheat genotypes had been evaluated at least three times. The infection type and percentage leaf area scored each time were used to calculate coefficients of infection (CI) and finally Area Under Disease Progress Curve (AUDPC) and relative AUDPC (rAUDPC). To evaluate the resistance of the genotypes at seedling stage. seeds of the entries were planted in 5cm diameter pots (4-6 seeds per pot) in the greenhouse. The seedlings were inoculated .with fresh harvested urediniospores of an isolate of Puccinia slriiformis f.sp. tritid (isolates collected from Karaj. Miandoab, Moghan, and Sari) 9 days after sowing, when the first seedling leaves were fully expanded. Inoculated plants were placed inside a small plastic covered cage and kept at 10 IIC and 90% RH in the darkness for 48 hrs. and then transferred into a greenhouse at 15 C. The reaction of each line or cultivar was evaluated using McNeal et al.. (1971) scale 15-17 days at\cr inoculation. A heavy epidemic of the disease was established in the nurseries of Karaj and Moghan in the lirst year. and Karaj and Maragheh in the second year of field tests but it was light in other locations. So only data collected from Karaj (in 1379-80 and 1380-81 cropping scasons). Moghan (1379-80). and Maragheh (1380) were used for analysis. Results of combined analysis of data (rAUDPC) by SAS for 1379 (in Karaj and Moghan). 1380 (in Karaj and Maraghd\). and Karaj (in 1379-80 and 1380-81 cropping seasons) showed signiticant differences (on level%1) between treatments (genotypes). Genotypes No. 4 (DMN/ISUT/AG (ES-S67‬ص‭) 13/0PATAl4rrX7IAI039-VI.3/AMI). (87ZHONG291), 2 (PVN"S"/CHIIISABALAN). and 10 (PVN"S"/CHIIISABALAN) had high levels of resistance to yellow rusts at all conditions in field. The results of seedling tests indicated that genotypes No.7. 2. and 10 were rcsistunt to the all tested isolates of yellow rust (isolates of Karaj. Miandoab. Moghan. and sari).‬