杂草对冬小麦的危害损失及经济防除阈值

1997—1999年在山东省桓台县的田间试验表明，荠菜 播娘蒿杂草群落有两个萌发出苗高峰期，除草临界期为小麦苗后的125-175天。杂草发生密度(株／m^2)与冬小麦产量(kg／hm^2)、有效穗数(万穗／hm^2)及秸秆生物量(kg/hm^2)的最佳模型均为直线函数关系，方程分别为Y3=-5．4545X 5995．5，Y4=-0．0293X 31．098和Y5=-8．329X 6987．1。使用巨星除草的经济防除阈值为20株／m^2，人工除草的经济防除阈值为70株／m^2。考虑到杂草群落的生长动态，本区秋季用巨星防除的最低密度为12株／m^2，并认为可以用步测法来粗略测定田间杂草防除密度。

Studies on the damage and economic threshold of weeds to winter wheat

In 1997 - 1999, field experiments were carried out to study the dynamics of shepherd-spurse-.sophia ( Capsella bursa-pastoris ) -tansymustaid ( Descurainia sophis ) community and its effect on the yield loss of winter wheat in Huantai, Shandong Province. There were two seedling emergence peaks of this weed community; the critical period to weed out these weeds was from 125 to 175 days after the wheat seedlings emerged. All the relationships among the weed density (plant number/m2, X) with wheat yield (kg/hm2, Y3) , effective wheat ear number (one unit= ten thousand ears/hm2, Y4 ) and biomass of wheat straw ( kg/hm2, Y5 ) were linear functions, i. e. Y3 = - 5.4545X + 5995.5; F4 = - 0.0293X + 31.098; and Y5 = - 8. 329X + 6987.1. By using tribenuron and hand weeding, the economic thresholds were derived as 20 and 70 plants/m2, respectively . While in consideration with the growth dynamics of this weed community, the least weed density to use tribenuron in autumn was determined as 12 plants/m . An ocular estimate method was recommended for deciding the weed density in wheat field.