地膜覆盖栽培的最大效应是提高土壤温度，春季低温期间采用地膜覆盖白天受阳光照射后，0－10厘米深的土层内可提高温度1－6℃，最高可达8℃以上。进入高温期，若无遮阴，地膜下土壤表层的温度可达50－60℃，土壤干旱时，地表温度会更高。但在有作物遮荫时，或地膜表面有土或淤泥覆盖时，土温只比露地高1－5℃，土壤潮湿时土温还会比露地低0.5-1.0℃，最高可低3℃。夜间由于外界冷空气的影响地膜下的土壤温度只比露地高1－2℃。地膜覆盖的增温效应因覆盖时期、覆盖方式、天气条件及地膜种类不同而异。
因此，当无灌溉条件降雨又少时，地膜覆盖甜菜受干旱威胁更大，故在干旱无灌溉地区不宜推广地膜覆盖技术。
Therefore, there were more menace to sugar beet covered with plastic film when in dry condition, no irrigation and little rain. So, the techniques of cover...
因此，当无灌溉条件降雨又少时，地膜覆盖甜菜受干旱威胁更大，故在干旱无灌溉地区不宜推广地膜覆盖技术。
Therefore, there were more menace to sugar beet covered with plastic film when in dry condition, no irrigation and little rain. So, the techniques of covered with plastic film...
因此，当无灌溉条件降雨又少时，地膜覆盖甜菜受干旱威胁更大，故在干旱无灌溉地区不宜推广地膜覆盖技术。
Therefore, there were more menace to sugar beet covered with plastic film when in dry condition, no irrigation and little rain. So, the techniques of covered with plastic film is inadvisable to...
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