水稻田周围几种植物上飞虱着卵株率与密度的关系

1984年晚季水稻及其田边几种植物上飞虱着卵株率与密度调查结果表明,飞虱着卵株率与卵密度呈曲线相关,着卵株率随卵密度的增加而增加,可用方程式P=αe~(bx)表示。当卵密度低时,着卵株率上升较慢,卵密度较高时,着卵株率上升较快。上述理论曲线是以卵的密度来计算着卵株率的。但在实际运用上要求以着卵株率来估计卵密度,这样省工、省时.又能准确估计卵的密度。文中列出了7种植物上飞虱卵密度与着卵株率的关系方程式,可供估算这几种植物上飞虱卵密度时参考。

STUDIES ON EGG DENSITIES AND PERCENTAGES OF TILLERS INFESTED WITH DELPHACID EGGS IN SEVEN PLANTS IN AND AROUND RICE FIELDS

In order to understand the relationship between egg densities and percen- tages of tillers with one or more Delphacid eggs,a series of observations were made in and around rice fields in later rice cropping,1984.It was found that this relationship can become curvilinear correlation shown in Fig.1,P is the function of x,and can be generally expressed by:P=αe~(bx) where α and b are constant,P is the percentage of tillers with one or more eggs,x is tile logarithm of egg density. But,in practice,we usually use P to estimate x.So we can transform above equation into x=1/b ln P-1/b ln α By calculating the parameter α's and b's,the following equations were obtained respectively in seven plants to facilitate the estimation of Delphacid egg densities. x=1.7787 ln P+4.2890(Zizania caduciflora) x=0.9431 ln P+3.9928(Echinochloa crusgalli) x=0.7663 ln P+3.8476(Oryza sativa L.) x=0.7362 ln P+3.7192(Cynodon dactylon) x=0.5589 ln P+3.5642(A species of Cyperaceae) x=0.4993 ln P+2.9912(A species of Graminaceae) x=0.4712 ln P+2 8623(Panicum repens)