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对几种螟害调查取样方法进行比较试验,并研究必要的样本数目。在不同栽植密度、不同螟害种类和螟害程度的田块中,一致麦示平行线取样法螟害率平均数的代表性误差最小,平均仅0.1,变异系数亦最小,平均23.56%,显著性测定结果:t 值亦最小,平均为0.6639,与对照的差异最小,可见平行线取样方法具有最大的准确程度。对角线和棋盘式取样法均显著差于平行线取样法,这两种取样法之间,基本上没有明显的差别。将样本数由240丛减少至120丛的平行线取样结果:240丛表现了明显的准确度;120丛在经验值螟害率0.8%以下的密度内,显现得很不准确;而在螟害率0.8%以上的密度尚勉强可用。根据大数定律原理,从理论上算出192丛即能满足所要求的准确度。根据试验结果,认为可以把目前螟害调查办法中的样本数240丛改为200丛。
Several test methods for the investigation of stem borers were compared and the number of samples required was studied. In fields with different planting densities, different stem borer species and the degree of stem borer damage, the representative error of the average number of stem borer was the smallest with an average of only 0.1 and the average coefficient of variation was 23.56% with an average of 23.56% Sex determination results: t value is also the smallest, with an average of 0.6639, the smallest difference with the control, showing the parallel sampling method has the greatest degree of accuracy. Diagonal and checkerboard sampling methods were significantly worse than the parallel line sampling method, the two sampling methods, basically no significant difference. The results of parallel lines sampling reduced the number of samples from 240 to 120 plexus: 240 plexus showed obvious accuracy; 120 plexus showed very inaccurate in density less than 0.8% Density of 0.8% or more is still barely available. According to the law of large numbers, 192 clusters can be calculated theoretically to meet the required accuracy. According to the test results, we think that it is possible to change the current number of 240 clusters in the investigation method of pest damage to 200 clusters.