Effect of different levels of calcium nitrate and potassium dihydrogen phosphate on powdery mildew (Erysiphe graminisDC) infection in resistant and susceptible barley and wheat

摘要

Cultivars of barley and wheat, resistant and susceptible to powdery mildew (Erysiphe graminis), were grown in perlite with added nutrient solutions in which the Ca(N03)2: KH2P04ratio was from one-third to three times the normal (1:1) amount in a balanced nutrient solution, i.e., 3:3, 3:1/3, 1/3:1/3, and 1/3:3. The degree of mildew infection was measured by planimetry, or by determining the number of conidia rer 10 g of leaf tissue or estimated visually. The Ethiopian barley cultivar CI 3926/3 was more resistant to mildew than #x2018;Kenia#x2019;, but the level of resistance varied depending on the Ca(N03)h : KH2P04ratio; both CI 3926/3 and #x2018;Kenia#x2019; were more resistant when grown in 1/3:3 than in the other treatments. Small darkbrown streaking lesions were produced on CI 3926/3 and to a lesser extent on #x2018;Kenia#x2019; grown in the high levels of Ca(N0}3h. #x2018;Aotea#x2019; wheat plants were also resistant to mildew when grown in 1/3:3 and to some extent in 3:3, but susceptible in 1: 1, 3:1/3 and 1/3:1/3. Chlorotic flecking lesions occurred on plants grown in Yd. #x2018;A Federation#x2019; wheat plants were immune to mildew in both 1/3:1/3 and 1/3:3.