麦田土壤中麦根腐离蠕孢菌量消长规律研究

关中粮田土壤中麦根腐离蠕孢繁殖体量于9月底前后处于低峰,小麦秋苗期有所上升,冬春逐渐减少,4月上旬前后达到另一个最低点。以后随着病害的发生发展,菌量回升,收麦前后达到最高峰。小麦后复种玉米或休闲的地块,菌量随病残体的分解而逐渐减少,下季小麦播种时达最低点。导致小麦灌浆期离蠕孢叶斑病流行的大量接种体源于本田麦株发病过程中菌量的积累,而非染菌土壤。

Population Growth and Decline of Bipolaris sorokiniana Propagule in Soils of Wheat Fields

Propagule population of Bipolaries sorokiniana (Sacc. ) Shoem. in soils of croplands was generally at a low tide around the late September in Guanzhong Plain. It might slightly increase at the autumn seedling stage of wheat,and later,gradually dcrease in winter and early spring time and reach another low tide a little before or after the first ten days of April. Afterwards, the propagule population of the fungus rapidly increases and reaches the highest peak of a year as a result of rapid development of root rot and Bipolaris leaf spot of wheat before or after harvest. In the fields with maize growing and/or fallow lands with winter wheat,population of Bipolaris sorokiniana in soil tends to decline along with the decomposition of wheat residues and reaches the lowest point in late September as mentioned above. The abounding inocula which caused epidemic Bipolaris leaf spots of wheat at milk stage were produced from diseased bases and spoted leaves developed from below to above the plants rather than infected soil.