小麦田阔叶杂草的生态经济杀除阈期研究

在麦田阔叶杂草达180－200株／m^2的情况下，进行了阔叶杂草的生态经济杀除阈期的研究，结果表明：苗后杂草干扰的相对时间（x)与相对产量（y)呈二次logistic曲线关系，表达式为：y=109.778/(1 exp(0.0071x-2.3281)）。苗后杂草的相对出苗时间（x）与小麦的相对产量（y)之间也呈二次logistic曲线关系，其表达式为：y=103.36(1 exp(-0.02x^2 0.0057x-1.5322)。根据上述两个模型进一步求出麦田阔叶杂草的生态经济杀除阈期约在小麦苗后的89－179天。此期间保持无草，有利于极大限度地控制杂草对小麦的危害。

STUDIES ON ECO- ECONOMIC THRESHOLD PERIOD FOR CONTROLLING BROAD- LEAFE WEEDS IN WHEAT FIELDS

The experiments were carried on the farm of Shandong Agricultural University in 1999-2000.The Eco-economic Threshold Period(ETP) of broad-leafe weeds such as Capsella bursa-pastoris , Descurainia sophia and Silens conoidea were studied in the wheat fields. The relation between the relative interfering time or emerging time of broad-leafe weeds and relative grain yield could be simulated by Miehaels-menten function:y=109.778/(1+exp(0.0071x-2.3281)) and y=103.36/(1+exp(-0.02x 2+0.0057x-1.5322)).Calculated by using these models,the results indicate that the ETP for controlling broad-leafe weeds in wheat fields ranges from 89 to 179 days after planting ,which is the critical period for removing all of the weed damage and controlling the loss created by the weeds maximally.