林木营养与虫害——油松施氮肥的抗虫效应

本文探讨了油松施氮肥后的抗虫效应。1981—1983年试验油松每年以两种方法施尿素5次。根施尿素每次用量为0.1和0.2公斤/株或采用重量比是1:200的尿素溶液进行叶面喷雾。实验结果如下:(1)枯梢率低于对照树;(2)松大蚜、松梢螟和红蜘蛛的虫口数量减少;(3)树皮和树叶中的总氮量、粗纤维素、粗灰分含量增加,而可溶性糖含量下降。经统计分析,上述结果和对照树相比有显著差异。结果表明,施氮肥不仅会增强树势,还会增强树的抗虫性而减轻虫害。我们认为,其主要作用机理是树木营养成分的明显改变影响了昆虫的生长发育和繁殖。

RELATIONSHIP BETWEEN TREE NUTRITION AND INSECT PESTS:THE EFFECT ON RESISTANCE TO INSECTS AFTER NITROGENFERTILIZER APPLICATION TO PINUS TABULAEFORMIS

This paper deals with the effect on resistance to insect pests after nitrogen fertilizer was applied to Pinus tabulaeformis. From 1981 to 1983 urea was used five times per year by two methods :soil application at. the rate of 0.3 and 0.2 kg/per tree each time or spray on foliage (urea: water=1 :200W/W). The results are summarized as follows: (a) The diebaek rate of branches and twigs was lower than that of control trees. (b) The amounts of Cinara sp., Dioryctria, splnuliddla and Oligonyclius berless in treated trees reduced, (c) The concentration of total nitrogen, crude cellulose and crude ash content in foliage and bark increased, but. the concentration of soluble sugars decreased. The statistical analysis indicated that all above mentioned results bad significant difference in comparasion with control trees. The results showed that the application of nitrogen fertilizer not only improved growth and development, of the trees, but, also improved the resistance of trees to the insect pests. The main reason for this was the great changes in nutrient composition of the trees, which affected the development and reproduction of the pests.