关键词: 发生机制, 氮肥, 叶色, 水稻, 病虫害

Abstract: The mechanism relationship between rice leaf color and diseases was discribed in this paper. Sheath blight(Thanatephorus cucumeris), bacterial leaf blight (Xanthomonas campestris pv. oryzae), brown planthopper [Nilaparvata lugens(Stal) and whitebacked planthopper [Sogatella furcifera(Horvath)] were selected to infest the different leaf color grade of rice population established by nitrogenous fertilizer application level in the experiments. The results showed that the damage caused by these diseases and insects in rice with dark-colored leaves were significantly greater than that in light-colored leaves. The occurrence could be explained in two aspects: On the one hand, amount of nitrogenous compound in lower molecular weight and net photosynthetic rate in creased with increasing color grade of the leaf, but carbon and nitrogen ratio(C/N) decreased, which might supply diseases and insects a good nutrient condition. On the other hand, rapidly increasing tillers of rice in dark-colored leaf created a crowded population, which might supply diseases and insects a suitable growth environment. The technique of nitrogenous fertilizer application according to rice leaf color was an effective measure for supplying seasonable nitrogenous nutrition for high yield and supressing both diseases and insect pests.

Key words: disease and insect pests, occurrence, nitrogenous fertilizer, leaf color grade, relationship