栽插密度、施氮量对水稻主要病虫害的综合生态效应

THE SYNTHESIZED ECOLOGICAL EFFECT OF RICE DENSITY AND NITROGEN FERTILIZER ON THE OCCURRENCE OF MAIN RICE PESTS

作者应用回归最优设计,评价了水稻栽插密度与施氮水平对稻飞虱、稻纵卷叶螟和水稻纹枯病发生为害的综合生态效应。结果表明,密度与氮肥均是诱发稻飞虱、稻纵卷叶螟和水稻纹枯病发生为害的主要因子,但影响的侧重点不同,密度主要影响稻飞虱、稻纵卷叶螟迁入虫量的再分配;氮肥对稻飞虱、稻纵卷叶螟种群动态的影响,以及对水稻纹枯病的水平扩展作用要大于密度的作用;而密度对水稻纹枯病的垂直扩展作用略大于氮肥的作用,二者的交互效应对稻飞虱、稻纵卷叶螟种群动态以及对水稻纹枯病的水平扩展与垂直扩展均有显著的影响。并应用数学原理进一步分析,探讨了利于水稻生长发育而不利于病虫繁殖流行的密度与氮肥的最佳组配方案。

An optimum regression design experiment was conducted in paddy rice field to estimate the synthesized ecological effect of transplantation density (X1) and application amount of urea (X2) on the occurrence of planthoppers (PH), composite populations of white-backed rice planthopper Sogatella furcifera (Horvath) and brown planthopper Nilaparvata lugens Stal), rice case worm (RCW) Cnaphalocrocis medinalis Guenee and rice sheath blight disease (RSB) caused by Rizoctonia solani Kuhn. The results showed that X1 and X2 were important factors with different actions separately on PH, RCW and RSB. The rice density mainly affected on the immigrated number and redistribution of PH and RCW,and the nitrogen mainly on their population dynamics. The effect of nitrogen was more stronger than that of rice density on the horizontal dispersion of RSB and some what weaker than that of the latter on its vertical dispersion. While all the population dynamics of PH and RCW as well as horizontal and vertical dispersion of RSB were significantly affected by the interaction of the two factors. Based on further mathematical analyses, the optimum combination of rice density and nitrogen favorable to the growth and development of rice and unfavorable to the rampancy of pests were explored.