玉米大斑病菌生理小种温度效应的初步研究

PRELIMINARY STUDY ON TEMPERATURE EFFECT OF PHYSIOLOGICAL RACES OF EXSEROHILUM TURCICUM IN CHINA

对玉米大斑病菌1号和2号2个小种的4个代表菌株的温度效应研究表明,2个小种在菌丝生长速度、菌丝生长量、孢子产生量以及致病毒素产生量等生物学特性方面的温度效应存在着一定的差异。1号小种对温度的适应范围较广,其上述各生物学特性的最适温度分别是25、25、20、20～25℃;而2号小种对温度的要求较1号小种严格,其上述各生物学特性的最适温度分别是20、20、25、15℃。此外还发现在适宜的产孢温度时,2号小种的产孢量极显著地高于1号小种。结论指出,长期以来温度可能是限制2号小种扩展、蔓延的主导因素之一,温度一旦适宜,大斑病菌2号小种会成为优势小种,并迅速导致Ht_1基因玉米的抗性丧失。

The temperature effect on 4 isolates belonging to race 1 and race 2 of Exsero-hilum turcicum (= Helminthosporium turcicum) have been studied. There were differences between the two races in temperature effect on some biological characteristics such as growth speed of hyphae,dry weight of hyphae ,sporulation and toxin production. The experimental results indicated that race 1 had wider temperature range than race 2. The optimum temperatures of the two races in nutritious growth,reproduction and toxin production were 25,25,20,20 -25℃ (race Dand 20,20,25,15℃ (race 2) respectively. Moreover, the sporulation quantity of race 2 was obvious higher than race 1 under optimum temperatures. It is resonable to conclude that the temperature may be one of key factors which limit spreading and pathogenecity of race 2 and this race may become dominant race and cause resistance lose of corn varieties with Ht1 gene under suitable temperature condition.