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本研究分别用“湘矮早9号”(早稻)及“洞庭晚籼”(晚稻)孕穗期叶片饲养稻纵卷叶螟幼虫,饲养期间温度分别为26-30℃及18-22℃,结果平均每虫食叶面积分别为20.38cm~2及22.68cm~2。幼虫食量增长规律类同“Dyar氏法则”,其中四龄食量约占20%,五龄约占70%。1982年在常德县湖区进行人工模拟试验,品种“湘矮早9号”,每亩施纯氮12.5公斤,剪叶叶位为剑叶(倒一叶)、倒二叶、倒三叶、剪叶面积为0、9、10、15cm~2四个级别。结果剪叶面积(X)与减产率(Y)的关系式为:Y=-1.34’+0.616X(r=0.85),当Y为2%时(经济允许水平),则X为5.7270cm~2,相当于每亩81,355头幼虫的取食量。所得结果与人工接虫试验基本一致,本文并讨论了产生差异的原因。
In this study, the larvae of C. medinalis were fed with booting stages of “Xiangchaowak 9” (early rice) and “Dongting late indica” (late rice) at the booting stage respectively. The temperature during the feeding was 26-30 ℃ and 18-22 ℃, respectively. The average leaf area per insect was 20.38cm ~ 2 and 22.68cm ~ 2 respectively. The law of growth of larvae appetite is the same as “Dyar’s law”, in which the fourth age food intake accounts for about 20% and the fifth age about 70%. In 1982, artificial experiment was carried out in the lake area of Changde County. The variety “Xiang-dai-zao 9” had 12.5 kg of pure nitrogen per acre. The leaf-cutting position was flag leaf (inverted one), inverted two leaf, inverted three leaf, Leaf area of 0,9,10,15 cm ~ 2 four levels. Results The relationship between the area of cut leaf (X) and yield (Y) was Y = -1.34 ’+ 0.616X (r = 0.85). When Y was 2% (the economic allowable level), X was 5.7270cm ~ 2, equivalent to 81,355 larvae per mu. The results obtained are basically the same as the artificial insects test, and the reasons for the differences are discussed in this article.