苜蓿锈病病菌侵染条件的研究

通过恒温箱和温室试验,探索了不同的保湿时间和温度对苜蓿锈菌孢子堆密度的影响以及不同培养温度对病害潜育期的影响。19℃下保湿(相对空气湿度100%)一定时间,再在25℃下生长15 d,可见保湿时间在12～48 h处理中植株叶片上孢子堆密度高于4～8 h。不同保湿温度下,保湿(相对空气湿度100%)24 h,再在25℃下生长15 d,试验结果表明随着保湿温度的升高,孢子堆密度先逐渐增加,在19℃左右达到最大,之后逐渐降低。19℃下,100%相对湿度下保湿24 h,然后分别置于15,20,25,30和35℃下生长,只有35℃下不发病,其余温度下潜育期分别为11,10,7和7 d;培养温度在25和30℃下的孢子堆密度显著高于15和20℃;培养温度对孢子堆显现时间的长短影响不大。

Factors influencing pathogenicity ofUromyces striatus

Uromyces striatus is the causal organism of alfalfa rust. The effects of humidity, temperature and time on disease severity and the effects of incubation temperature on the latent period of alfalfa rust were investigated using growth chamber and greenhouse experiments, respectively. Alfalfa plants were inoculated with U. striatus and incubated at 19℃ with 100% relative humidity (RH) for different periods before being transferred to 25℃ conditions for 15 days. Subsequently, spore densities on the leaves of inoculated plants were assessed. The results showed that spore density of treatments incubated at 19℃ for 12 h to 48 h was significantly higher than those incubated for 4 h to 8 h. Plants were also inoculated and incubated at 19℃ with 100% RH for 24 h and then transferred to different temperature environments; 15, 20, 25, 30 and 35℃. Plants transferred to 35℃ conditions did not display any alfalfa rust symptoms. The disease latent period on inoculated plants grown at 15, 20, 25 and 30℃ was 11, 10, 7 and 7 days, respectively. The spore density on leaves in the 25 and 30℃ treatments was significantly higher than the 15 and 20℃ treatments. There was no relationship between incubator temperature and disease latent period.