本研究分为三个部分:1.为害产量损失率的测定;2.田间虫口密度与产量损失率的回归分析;3.化防指标的确定。 一、损失率的测定及统计分析 1.取样方法 采用L_8(2)~7正交表三因素二水平完全组合的设计方案,将水稻成熟期间顶部三张叶片,即剑叶(A)、顶下第二叶(B)、顶下第三叶(C),看作是三个不同的因素,把它们受稻纵卷叶螟的为害与否 The research is divided into three parts: 1. Determination of yield loss rate; 2. Field regression analysis of insect population density and yield loss rate; 3. First, the loss rate of the measurement and statistical analysis 1. Sampling method using L_8 (2) ~ 7 orthogonal table three factors and two levels of a complete combination of design options, the top three leaves during ripening rice, that is, the flag leaf (A) Under the second leaf (B), under the third leaf (C), as three different factors, whether they are affected by the rice leaf roller or not