Powdery mildew susceptibility of spring wheat cultivars as a major constraint on grain yield

Powdery mildew infection caused by Blumeria graminis f. sp. tritici and grain yield of 23 spring wheat cultivars were investigated under controlled and natural conditions during two growing seasons (2016/17 and 2017/18). Under controlled greenhouse conditions, seedling infection types of 9 cultivars, Sids-12, Sids-13, Gemmeiza-3, Gemmeiza-10, Sakha-61, Sakha-93, Sakha-94, Giza-160 and Giza-163 revealed susceptibility to the disease, while 14 cultivars, Misr-1, Misr-2, Sids-1, Gemmeiza-1, Gemmeiza-5, Gemmeiza-7, Gemmeiza-9, Gemmeiza-11, Gemmeiza-12, Sakha-8, Sakha-69, Giza-167, Giza-168 and Giza-171 showed resistance during both seasons. In the field, adult plant infections revealed susceptibility of 8 cultivars, Gemmeiza-3, Gemmeiza-5, Gemmeiza-7, Sakha-8, Sakha-61, Sakha-93, Giza-160 and Giza-163, while 7 cultivars, Misr-2, Sids-13, Gemmeiza-11, Gemmeiza-12, Giza-167, Giza-168 and Giza-171 exhibited resistance during both seasons. These last-mentioned 7 cultivars also showed best resistance in seedling infection tests during both seasons. The highest levels of disease severity were recorded with Gemmeiza-3, Sakha-61 and Sakha-94, while the lowest ones were in Giza167 and Giza-168 as resistant cultivars. Significant losses in grain yield (1000-kernel weight) were recorded with highly susceptible cultivars, reaching 26.68% in Gemmeiza-3, while insignificant loss was recorded with resistant cultivars, 2.06% in Giza-168. A strong positive correlation was observed between % disease severity and % loss in 1000-kernel weight, recording r = 0.9195 in the first season and r = 0.9402 in the second season. In susceptible cultivars, disease was an important yield constraint. Resistant cultivars may be incorporated in breeding programs to prevent yield losses.