夏大豆田稗草的生态经济防治阈期研究

ECO-ECONOMIC PERID THRESHOLD FOR CONTROLLING BARNYARDGRASS (ECHINOCHLOA CRUS-GALL L ) IN SUMMER SOYBEANS

本文提出了杂草生态经济防治阈期的概念。并在北京地区1984和1985年田间试验的基础上,建立了苗后放任和免除夏大豆田稗草生长的相对天数与大豆相对产量的函数关系及其生态经济防治阈期的计算模型。利用此模型计算的结果表明,夏大豆田稗草的生态经济防治阈期处在大豆苗后生育期总天数的16.8％—26.0％之间;即按绝对天数计算,北京地区夏大豆田该杂草的生态经济防治阈期约处在大豆苗后15—23d之间。此期保持无草,可望既能生态经济地控制夏大豆整个生长季节期间发生的所有稗草的危害,又能最大限度地发挥稗草在防止农田水、肥、土流失等方面的有益作用。

A terminology of Eco-economic period threshold for weed control' was proposed, on this basis, field experiments were conducted during 1984 and 1985 in Beijing region to fit the functional relationships between the relative weedy or weedfree days of Echinochloa crus-gal-li and the relative yield of summer soybeans. Finally,calculating models of the eco-economic period threshold for controlling the wd were established.Results calculated by using these models showed that the eco-economic period threshold for controlling Echinochloa crus-galli in summer soybeans ranged from 16. 8% to 26. 0% days of the crop growch .Season after emerg ence This is the critical period to remove all of the weed damage and to maximize the role of the weed flora in reducing the losses of water,nutrients and soil during the growth season of summer soybeans.