小麦白粉菌分生孢子离体后存活时间与温度的定量关系研究

The Correlation between temperature and survival time of conidia of Blumeria graminis f.sp.tritici in vitro

小麦白粉病是我国小麦生产上的重要病害之一，由专性寄生真菌Blumeriagraminisf．sp．tritici引起。此病害是典型的气传病害。病菌分生孢子可借助高空气流远距离传播为害，高空传播距离与病菌的分生孢子存活时间有直接关系，而温度是影响病菌孢子存活时间最主要的因子之一。

Blumeria graminis f. sp. tritici （Bgt）, which caused wheat powdery mildew disease, survive in very short period away from the host wheat. In order to determine the survival time of conidia of Bgt in vitro, conidia germination and disease severity of wheat leaves infected by Bgt conidia were studied after treatments with serial temperatures and time. The results showed that conidia germination rates and disease severities were decreased as temperatures increased. There was no conidia germination and wheat infection when the conidia were kept at 30℃ for 1 d. After keeping at 25℃-28℃ for 1 d, the conidia germination rate was 11.1%-21.8%, and disease severity was 10.6%-15.5%. At 14℃-22℃ for 1 d, the conidia germination rate was 27.4%-29.1%, and severity was 35.5%-69.1%, while no conidia germination and wheat infection for 4 d. As well as, the conidia were kept at 4℃-8℃ for 1 d with 36.6%-43.2% germination rate and 82.5%-91.0% severity, while the germination rate was 5.0%-6.7%, and severity was 7.8%-16.0% after kept for 8 days. All these data indicated that there was a significantly negative correlation between survival time of conidia of Bgt in vitro and temperature, the lifetime of conidia decreased along with temperature increased, such as 8 d at 4℃-8℃, 3 d at 18℃-22℃, 1 d at 25℃-28℃, and less than 1 d at 30℃. Based on these results, a model of relationship between survival time of conidia of Bgt in vitro and temperature was constructed. These could provide the basis for modeling dispersal distance of wheat powdery mildew.