豫北露地直播棉田杂草的发生及其与棉花的竞争作用

Mixed Weeds and Competition with Directly Seeded Cotton,North Henan Province,China

为了明确棉田自然混生杂草对棉花的危害程度及其关键防除时期,通过田间杂草共生期试验,研究了豫北露地直播棉田杂草的发生及其与棉花的竞争临界期。结果表明,豫北地区露地直播棉田的优势杂草为牛筋草、马齿苋、藜和鳢肠,杂草出土高峰期集中在棉花苗期和花蕾期,且存在3个出土高峰,分别在5月中旬、6月上中旬和7月中下旬。当杂草与棉花竞争持续时间少于4周时,由于杂草与棉花植株均较小,且土壤中养分相对充足,因此杂草对棉花生长和产量的影响不大;当杂草与棉花竞争期达8周以上时,杂草对棉花的竞争作用明显增强,棉花的株数减少,茎秆变细,形成瘦高植株,且单株结铃数、铃重等产量指标明显降低。因此,豫北棉田自然混生杂草群落与棉花的竞争临界期为棉花出苗后4～8周,在此期间应采取相应措施,保证田间无草害。

In order to understand the degree of damage caused by mixed weeds,and the critical control period,a field experiment was conducted to investigate weed occurrence and the critical period of competition in a directly seeded cotton field in North Henan Province.Eleusine indica（L.） Gaerth,Portulaca oleracea L.,Chenopodium aldum L.,and Eclipta prostrata L.were dominant weed species in the cotton field over the whole growing season.Weeds germinated mainly between the seedling stage and the budding stage of the cotton,with three peaks in weed seedling emergence in mid-May,early to mid-June,and mid to late July.Duration of weed competition less than four weeks did not significantly affect cotton growth and yield because soil nutrients were sufficient for both weed and cotton seedlings.However,the number of cotton plants,stem diameter,and yield component factors including boll number per plant and boll weight,were reduced when weed competition lasted up to 8 weeks.Therefore,the critical period for weed control in cotton was between 4 and 8 weeks after cotton emergence,and effective weed control measures should be implemented to minimize cotton losses