Seasonal changes in pathotype complexity in French populations of barley powdery mildew

Airborne conidia of Erysiphe graminis f.sp. hordei were sampled in three regions and a single locality in the northern part of France for 2 years. Sampling was carried out in early spring, in late spring and in autumn, in order to separate the effects of winter barley cultivars, carrying few specific resistance alleles, and of spring barley cultivars, carrying diverse resistance alleles, on the structure of the pathogen population. Although complex pathotypes with three to 10 virulences were selected by spring cultivars, simple pathotypes, including a pathotype with the single unnecessary virulence allele Va22 , which formed a clear majority of the samples, remained dominant in early spring, when winter but not spring cultivars were growing. In early spring, simple pathotypes were more prevalent in the north, where the winter cultivars represented 90% of the barley acreage, than in the east, where winter cultivars represented 65%. In the west, the frequency of simple pathotypes was limited compared to the north, possibly because of the resistance allele Mlg in winter cultivars. The high frequency of simple pathotypes in early spring could be explained by a differential adaptation between simple and complex pathotypes or by delayed epidemics on spring cultivars compared to winter cultivars.     

西藏高寒区禾-豆混播对牧草营养品质及土壤养分的影响

采用随机区组试验设计,以燕麦(Avena sativa)、箭筈豌豆(Vicia sativa)、饲用豌豆(Pisum arvense)为材料,于2019年在拉萨墨竹工卡具开展单播、禾-豆混播种植方式下牧草产量和品质的比较.通过分析种植后土壤养分的变化,在确保牧草生产性能的同时,探讨禾-豆混播的土壤改良作用.结果表明:(...