【摘要】 在不同的氮肥施用水平下 ,覆膜均使玉米的绝对株高增加 ,株高日增速、叶面积增长速率提高 ,这为提高光能利用率创造了良好的条件。在各氮素水平下 ,覆膜使叶片中叶绿素含量前期 (7月 2 8日前 )降低 ,后期增加 (7月 2 8日后 )。覆膜并没有明显地改变氮素肥料效应形式 ,只是提高了肥料效应 ,氮素的增产作用更加明显。经济分析结果表明 ,覆膜后增加了氮肥施用利润 ,在最佳施肥点 (R=0 )比露地亩增利润 2 5 .5 6元 ,而施肥量却降低了0 .3kg/亩 ,肥料成本降低了 0 .91元 /亩 ,因此覆膜也降低了氮肥的投资风险更多还原

【Abstract】 Under the different level of applying nitrogen fertilizer,the absolute plant height was increased with film,and the growth rate of plant height and leaf area was increased,too. It brought about good condition for increasing light utilization.Under the different level of nitrogen fertilizer,the chlorophyll content of leaf was decreased with film before 28 on July,but it was increased after 28 on July.It indicated that the nitrogen element productivity was improved.The effect form of nitrogen fertilizer was not changed evidently,only was the effect of fertilizer increased and the function of increasing yield was more obvious.The economic analyzing results indicated that the profit of applying nitrogen fertilizer was increased with film,and it was increased by 25.56 Yuan per mu at the best spot of application,but the amount of applying fertilizer was decreased by 0.3 kg per mu and the fertilizer cost was decreased by 0.91 Yuan per mu.So the risk of investment was also decreased with film.更多还原