皖西南直播棉田杂草群落出苗模式

为明确皖西南直播棉田杂草群落出苗模式及其与气象因子的相关性,采用定点定时调查法,于2010—2012年对棉田杂草种类、数量及群落结构进行调查,分析物种多样性,并以灰色关联度法分析直播棉田杂草群落出苗数量与气象因子的相关性。结果表明,皖西南棉区直播棉田杂草种类有13科24种。棉田杂草出苗有2次高峰,分别在5—6月和8—9月。棉田杂草群落多样性指数年度间变化较一致,但物种丰富度变化较大。周积温、周最高积温和周最低积温是影响皖西南直播棉田杂草群落出苗数量季节变化的主要因素,另外还受降水量影响。5—6月的杂草出苗高峰期是棉田杂草重点防治时期;相对占优势的杂草有牛筋草、千金子、旱稗、通泉草和马齿苋,是棉田杂草重点防治对象。

Emergence pattern of weed seedling community in direct-seeding cotton fields in the southwest of Anhui Province

To clarify the emergence pattern and its influential factors of weed communities in direct-seedling cotton fields, weed density, species number and community structure were investigated by fixed time and location survey in southwestern Anhui Province. The species diversity and the relationship between meteorological elements and the seedling pattern were analyzed by using grey correlation analysis. The results showed that 24 weed species, which belong to 13 families, existed in direct-seedling cotton fields. Weed emergence showed two peaks, the first between May and June, and the second between August and September. The diversity characteristic values in weed community had the same trend among different years, while species richness was different. The seasonal fluctuation of weed seedlings was affected dominantly by weekly accumulative temperature, maximum weekly accumulative temperature and minimum weekly accumulative temperature; rainfall was the secondly important factor. The weed emergence peak between May and June was key weed control period in cotton fields. The key control objects were the relatively dominant species, such as Eleusine indica, Leptochloa chinensis, Echinochloa hispidula, Mazus japonicus and Portulaca oleracea.