水稻叶色与病中发生关系及其机制研究

The Relationship between Rice Leaf Color and Occurrence of Rice Diseases and Insects and Its Mechanism

在盆栽和田间条件下研究了不同施氮量产生的不同叶色水稻群体与稻纹枯病、白叶枯病、褐飞虱和白背飞虱发生的关系及其机制．深绿色叶片水稻的纹枯病、白叶枯病、褐飞虱和白背飞虱的发生程度显著或极显著大于浅绿色叶片水稻、其原因为叶色深后，叶片低分子态氮含量增加，净光合率提高，碳氮比值降低，为病虫生存繁殖提供了较为适宜的营养条件；稻侏分蘖数猛增，形成庞大面郁闭的群体结构，为病虫滋生创造了合适的环境条件．根据叶色深浅追施氮肥、既可满足水稻高产氮素需求，又可抑制病虫发生。

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 cstablished 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 as pects: 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)decrcased which might supply diseases and insects a good nutrient condition.On the other hand.rapidly increasing tillers of rice in dark-colored leafcreated 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.