ارزيابي مزرعه‌اي مقاومت تدريجي (Slow rusting) نسبت به بيماري زنگ زرد در برخي از ارقام گندم ديم

Field-based assessment of slow rusting resistance against yellow rust in some dryland wheat cultivars

زنگ زرد گندم با عامل Puccinia striiformis f. sp. tritici يكي از مهمترين بيماري‌هاي گندم مي‌باشدكه توليد گندم را در مناطق خنك تهديد مي‌كند. در اين مطالعه، پارامترهاي مقاومت تدريجي (Slow rusting) شامل ضريب آلودگي (CI)، شدت نهائي بيماري (FRS)، مقدار نسبي سطح زير منحني پيشرفت بيماري (rAUDPC) و نرخ آلودگي ظاهري (r) براي 21 ژنوتيپ گندم ديم همراه با شاهد حساس ارزيابي شدند. اين مطالعه در ايستگاه تحقيقات كشاورزي آلاروق اردبيل تحت شرايط آلودگي طبيعي و مصنوعي انجام شد. آلودگي مصنوعي ژنوتيپ‌ها با استفاده از جمعيت نژادي زنگ زرد كه داراي پرآزاري بر روي ژن‌هاي مقاومت مهم بود، انجام شد. واكنش گياهچه‌اي نيز تحت شرايط مزرعه‌اي ارزيابي شد. نتايج ارزيابي‌ها براي پارامترهاي مقاومت نشان داد كه ارقام سرداري، اوحدي، هما همراه با رقم حساس بالاترين مقادير FRS ، CI، r و rAUDPC را داشتند، و بنابراين به عنوان ارقام حساس گروه‌بندي شدند. شش رقم در هر دو مرحله گياهچه‌اي و گياه كامل مقاوم يا نيمه مقاوم بودند. دو رقم در مرحله گياهچه‌اي مقاوم يا نيمه‌مقاوم و در مرحله گياه كامل واكنش متوسط (MR, M) نشان دادند. نه رقم (شماره هاي 6، 9، 10، 12، 14، 15، 19، 20 و 21) در مرحله گياهچه‌اي حساس ولي در مرحله گياه كامل واكنش متوسط (MR, M, MS) نشان دادند. بنابراين، اين ارقام با داشتن مقادير پايين پارامترهاي مختلف مقاومت به احتمال زياد داراي درجات متفاوتي(سطح مطلوب تا متوسط) از مقاومت تدريجي يا HTAP (مقاومت غير اختصاص- نژادي يا پايدار) مي‌باشند. بقيه ارقام سطح پاييني از مقاومت تدريجي داشتند.

Yellow rust caused by Puccinia striiformis f. sp. tritici is an important disease that threatens wheat production in the world. Host resistance is the most economical and safe strategy to manage wheat stripe rust; and slow rusting resistance, a kind of quantitative resistance, has been reported to be more durable than other kind of resistances. Slow rusting parameters including final rust severity (FRS), apparent infection rate (r), relative area under disease progress curve (rAUDPC), and coefficient of infection (CI) were evaluated in a set of twenty-one dryland wheat genotypes along with susceptible control in 2017 and 2018 growing seasons. This study was conducted in field plots at Ardabil and Agricultural Research Stations under natural and artificial infection conditions. Artificial inoculation was carried out by yellow rust inoculum containing virulent genes against Yr1, Yr2, Yr6, Yr7, Yr9, Yr17, Yr21, Yr22, Yr23, Yr24, Yr25, Yr26, YrA, YrSU, Yr27, Yr31, and Yr32. Seedling reaction was also evaluated under field conditions. Results of evaluations for resistance parameters showed that cultivars Sardari, Ohadi, Homa along with susceptible check (Morocco) had the highest values of FRS, CI, r, and rAUDPC, therefore they were mined as susceptible cultivars. Six cultivars were resistant or moderately resistant both at the seedling and adult plant stages, two cultivars including Sabalan and Cheheldaneh, showed resistant or moderately resistant reactions at seedling, but moderate or moderately susceptible reactions at the adult plant stage. Nine cultivars; Alvand, Rijaw, Baran, Zagrous, Dehdasht, Zardak, Sadra, Saein and Saji were susceptible at the seedling and had moderate (MR, M, or MS) reactions at the adult plant stages. Hence, these cultivars with a low level of different parameters supposed to be having gene/s for varying degrees (good or moderate level) of slow rusting resistance or high-temperature adult plant (HTAP) resistance. The remaining cultivars/lines had low level of slow rusting resistance. Cluster analysis of different cultivars/lines based on adult plant resistance parameters and seedling infection types revealed different groups/clusters which indicate considerable diversity for a level of resistance of these wheat genotypes. Genotypes with good and moderate levels of slow rusting resistance that have been identified in this study can be cultivated instead of susceptible cultivars or used in wheat breeding programs for yellow rust.