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试验结果表明,在自然情况下,杂交中稻田害虫及天敌的种群密度,随着施氮量的增加而增加,其幅度因年度而异,中等发生年大于大发生年。在同一施氮量下,田水深浅对害虫的效应,因害虫种类而不同,白背飞虱和褐稻虱明显,稻纵卷叶螟和稻蓟马没有差异。杂交中稻在不防治害虫的情况下,因受害虫为害而造成的损失,与施氮量呈正相关。多施氮肥区比药剂保护区减产5成以上;一般施氮水平减产3成;少施氮肥的减产2成左右。
The results showed that under natural conditions, population density of pests and natural enemies in mid-season hybrid rice increased with the increase of nitrogen application rate. Under the same nitrogen application rate, the effect of the depth of field water on pests was different according to the species of pest, but there was no difference between the white-backed planthopper and the brown planthopper. In the case of non-pest control hybrid rice, the damage caused by pest infestation was positively correlated with the amount of nitrogen application. Multi-application of nitrogen fertilizer area than the chemical reduction of more than 50%; general nitrogen level reduction of 3 percent; less nitrogen fertilizer reduction about 2 percent.