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根据有代表性的２ 县１０５ 块夏玉米田调查，菏泽地区夏玉米田杂草种类共１７ 科３５ 种，分析探明优势种类１２ 种。试验表明不同杂草混合种群密度与夏玉米产量损失率相关极显著，相关式为ｙ＝４ ．７２３ ６ ＋ ０ ．１８７ ４ｘ 。提出其化学除治指标为每平方米有杂草２０ 株。
According to the survey of 105 summer maize fields in 2 counties, 35 species of weeds were found in summer maize fields in Heze area, and 12 species of dominant species were analyzed. Tests showed that the density of mixed weed populations was significantly correlated with the yield loss of summer maize, the correlation was y = 4. 723 6 + 0. 187 4x. Put forward its chemical removal indicator 20 per square meter of weeds.