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研究了在持续低温(1～7d,≤20℃)作用下,具有不同抗性的品种汕优多系1号(抗病)和汕优63(感病)对稻瘟病菌的抗性变化。结果表明:(1)持续低温(≤20℃)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(如7d以上),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。其病斑增长率大小依次为:处理5d>处理3d>对照>处理1d>处理7d,处理过长则不利于病斑扩展,过短则效应不明显。(3)低温处理使过氧化物酶(PO)活性值显著高于对照。低温处理1d苯丙氨酸解氨酶(PAL)活性值比对照要高,但1d之后却开始下降,感病品种下降更快。经低温处理后总酚含量值比对照下降,且抗病品种在第3d、感病品种在第5d分别出现最低峰,表明低温削弱了稻株的抗病性。因此,持续低温3～5d不仅有利于稻瘟病菌的侵入和病斑显现,而且也有利于病斑扩展,从而使病害得以发生和流行。
The changes of resistance to Magnaporthe grisea in Shanyouduo 1 (resistant) and Shanyou 63 (susceptible) cultivars with different resistances under continuous low temperature (1 ~ 7d, ≤20 ℃) were studied. The results showed that: (1) The treatment of continuous low temperature (≤20 ℃) occurred 2 ~ 3d earlier than that of the untreated rice blast; the number of lesions was the highest at 3 ~ 5d after low temperature treatment, Over time (such as 7d above), is not conducive to disease. (2) Continuous low temperature treatment 3 ~ 5d significantly affected the spread of lesions. The lesion growth rate of the order: treatment 5d> 3d> control> 1d> treatment 7d, the treatment is too long is not conducive to disease spread, too short, the effect is not obvious. (3) The activity of peroxidase (PO) was significantly higher than that of the control at low temperature. Phenylalanine ammonia-lyase (PAL) activity at 1 day after cold treatment was higher than that of the control, but decreased after 1 day, and the susceptible varieties declined more rapidly. After low temperature treatment, the content of total phenols decreased compared with the control, and the resistant cultivars showed the lowest peak at the 3dth and the susceptible cultivars at the 5th day respectively, which indicated that low temperature weakened the disease resistance of rice plants. Therefore, continuous low temperature of 3 ~ 5d not only conducive to the invasion of M. grisea and lesions show, but also conducive to disease spread, so that disease can occur and prevalence.