零频率估计二化螟危害株密度方法的研究

Methods of Estimating Density of Rice Plants Damaged by Chilo suppressliss Walker by Zero Frequency

零频率估计二化螟危害株密度的３种方法为：（１）Ｘ＝０．８７４３（Ｐ０－１．１４３８－１）；（２）Ｘ＝ｅｘｐ｛［ｌｎ（－ｌｎＰ０）＋０．６９９７］÷０．９５１４｝；（３）Ｘ＝２．０１３１（－ｌｎＰ０）１．０１５３。其中以第３种方法估计精度最高，误差小，应用效果最好。依据Ｇｅｒｒａｒｄ方法建立了理论抽样数模型：ｎ＝ｂ２（１－Ｐ０）／Ｐ０（ｌｎＰ０）２（ｃｖ）２。田间验证表明，样本数５０～１００丛，即可把抽样误差控制在２０％以内，完全符合田间调查精度要求。

Abstract Three methods for estimating the density of rice plants damaged by Chilo suppressalis Walker based on zero frequency were compared. The model based on the Gerrare′s method was best for higher precision and lower error in estimation the sample quantity was calcalated as n= b 2(1-P 0)/P 0(lnP o) 2(cv) 2 The field test results showed that the sample error was less than 20% with sample quantity of 50-100 clusters Investigation precision in fields was good and working efficiency increased by using new method.