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(2) 关棚与揭盖保温膜塑料大棚的保温能力很差,夜间的棚温只比外界高2℃左右,有时甚至相同。因此大棚栽培瓜叶菊通常必须有多层覆盖保温。覆盖多用薄膜,草帘笨重易潮,遮阳网不密封,只起辅助使用。将它们在下午至傍晚时层层覆盖(为提高保温效果,两层保温膜之间应有一定的空间)在植株上方,通过防对流防辐射的方式阻挡夜间棚温的急剧下降。
(2) Off the shed and uncovering the thermal insulation ability of the plastic shed is very poor. The shed temperature at night is only about 2 ℃ higher than the outside world, sometimes even the same. Therefore, greenhouse cultivation of cineraria usually must have multiple layers of insulation. Cover with multi-purpose film, straw blind easy to tide, shade net is not sealed, only from the auxiliary use. They are covered layer by layer from afternoon till evening (there should be some space between two layers of insulation film to improve the insulation effect). Above the plants, the nighttime shed temperature is blocked by the anti-convection radiation protection.