Magnesium and sulfur fertilisation - effects on foliar disease infection in perennial ryegrass

摘要

A three-year field experiment demonstrated that magnesium (Mg) and sulphur (S) supplementation in addition to standard nitrogen, phosphorus and potassium fertilisation significantly (P < 0.001) reduced the crown rust [Puccinia coronata; PC) infectionof 33 perennial ryegrass (Loliumperenne L.) cultivars cultivated in Mg-deficient soil. The coverage of leaf area by pustules was reduced from 2.6 to 2.4 points on a 1 to 9 scale, with one designating the absence of disease. Leaf spot (Drechslera siccans;DS) infection with supplemental Mg-S treatment was increased by 0.1 points (P < 0.001) in relation to standard fertilisation. Crown rust resistance of the tetraploid cultivars was significantly (P < 0.001) better than diploid cultivars, but tetraploid cultivars were more susceptible to DS (P < 0.001). Leaf spot was more injurious to perennial ryegrass than PC as its symptoms developed earlier in summer and occupied a larger leaf area (4.0 and 2.5 points, respectively).