持续低温对水稻稻瘟病抗性的影响

研究了在持续低温作用下，具有不同抗性的品种汕优多系１号和汕优６３对稻瘟病菌的抗性变化。结果表明：（１）持续低温处理比未经处理的对照稻瘟病病斑要早出现２－３ｄ；低温处理３－５ｄ出现病斑数目最多，对病害发生最为有利；但处理时间过长，则不利于病害；（２）持续低温处理３－５ｄ对病斑扩展的影响显著。

EFFECT OF CONTINUOUS LOW TEMPERATURE ON RESISTANCE OF RICE TO RICE BLAST CAUSED BY PYRICULAR1A GRISEA

Two rice cultivars, Shanyou duoxi 1, resistant, and Shanyou 63, susceptible to rice blast were used to analyze the variation of the resistance to Pyricularia grisea under low temperatures, <20 C that is. The results showed that lesion appeared two or three days earlier than the control which was not exposed to low temperature. The rate of infection increased after 3 - 5 days under low temperature but not long exposure to low temperature, such as longer than seven days. Low temperature lasted for 3 - 5 days favored lesion spread significantly. The order for the rate of lesion spread was 5-day>3-day>control>l-dayL>7-day. This indicated that treatment for too long or too short period time was not advantageous to lesion development. The activities of peroxidase and phenylalanine ammonia lyase were higher than that of the control while the total phenol content was lower than that of the control. This indicated the low temperature decreases the resistance of rice. As a result, continuous low temperature for 3 - 5 days favored not only the infection of P. grisea but also the development of lesions. The disease was apt to occur and become epidemic.