黄淮海地区夏玉米田一年生杂草的生态经济防治阈期研究

ECO-ECONOMIC THRESHOLD PERIOD FOR CONTROLLING WEEDS IN SUMMER MAIZE FIELD OF HUANG-HUAI-HAI REGION

本文通过北京和唐山多年多点田间试验，研究了黄淮海地区夏玉米田苗后放任和免除自生一年生杂草生长的相对时间与夏玉米相对产量的函数关系，并据此导出了该区夏玉米田一年生杂草的生态经济防治阈期计算模型。结果发现，该区夏玉米田一年生杂草的生态经济防治阈期约处在夏玉米苗后总生育期的（天）第１１．２－５０．９％之间．核区夏玉米生长季节中只要此期田间保持无草，便可望以最小的代价和费用，最大限度地使杂草弃害扬利，从而获得较高的生态经济除草效益。

Field experiments were conducted in 1992 and 1993 in Beijing and Tan- gshan regions, two representatives of the Haung-Huai-Hai region,to study the functional relationships between the relative weedy or weedfree days of naturally infecting weeds and the relative yield of summer maize,Models for calculating the eco-economic threshold period for controlling the weeds in aize feild were established.The results showed that the eco-economic threshold period for controlling the naturally infecting weeds in summer mai- ze feild ranged from 11.2% to 50,9%of the total growth days of maize after crop emergence in this region,This is the critical period to remove all of the weed damage and to maximally utilize the role of the weed flora in reducing theloss of water,nutrients and soil during the growth season of maize in this region.