واکنش خزانه بین‌المللی گندم نان به بیماری زنگ زرد در مرحله گیاه کامل در منطقه گرگان

Variation and selection play a key role in breeding programs and the proper selection is related to the desired variation in the desired trait. It seems to take advantage of the existing variation; the evaluation of germplasm resources is necessary. Yellow rust disease (Puccinia striiformis f. sp. tritici) is the most important wheat disease in Iran that is observed in most parts of the country. The warm and humid agro-climatic zone of northern Iran is prone to the emergence of this disease due to high relative humidity. The use of resistant cultivars is the most economical way to reduce the application of chemical fungicides. In order to select the top lines of 52thIBWSN Nursery (International Bread Wheat Screening Nursery); received from the International Maize and Wheat Improvement Center (CIMMYT), 273 spring bread wheat genotypes were evaluated as observational approach at Gorgan Agricultural Research Station in the 2019-2020 cropping season. To further spread the yellow rust infection, Falat cultivar (susceptible) was cultivated in the margin of the trail. Tirgan cultivar was also used as a resistant control. After the complete establishment of the disease on the susceptible cultivar in the adult plant stage, taking notes in the stage of flag leaf emergence were recorded based on the infection type, as susceptible (S), moderately susceptible (MS), resistant (R), moderately resistant (MR) and immune (O). Infection severity was also graded from 0-100. The coefficient of infection (CI) was calculated by multiplying the disease severity in the constant values that is related to the plant response (O = 0, R = 0.2, MR = 0.4, MS = 0.8 and S = 1). Due to the favorable climatic conditions for the pathogen, in March and April, yellow rust disease was well established and spread. The results showed that based on the infection type, 121 lines (44%) were moderately resistant and 53 lines (19%) were moderately susceptible and 50 lines (18%) were susceptible to yellow rust. Also, no signs of infection were observed in 49 lines (18%). Based on the coefficient of infection (CI), 166 lines (61%) were resistant, 29 lines (11%) were moderately resistant, 15 lines (5%) were moderately resistant to moderately susceptible and 15 lines (5%) were moderately susceptible. Of the top 10 lines in terms of grain yield, four, six and four lines were immune and resistant to yellow rust disease, respectively.