久阴低温由于光照不足,光合作用弱,营养不良,生长缓慢,叶色淡。易发生僵苗和猝倒病.防治方法:白天上午揭去草苫,扫除薄膜上的尘土,拍掉凝集在薄膜内侧的小水珠,保持透明度.增加光照,提高温度.夜间加盖草苫保温.久阴曝晴许久阴雨,突然曝晴,会使床内温度剧烈升高,瓜苗失水过多、过抉,发生生理水分 Long Yin low temperature due to lack of light, photosynthesis weak, malnutrition, slow growth, pale leaf color. Prone to stiff seedlings and damping off disease. Prevention and treatment methods: the day when the grass was removed, remove the dust on the film, shot off the small droplets of water gathered in the film inside, to maintain transparency. Increase the light, raise the temperature. Long-lasting shade exposed a long time rainy, suddenly exposed to the sun, will make the temperature of the bed violently increased, too much water loss melon seedlings, too much, the occurrence of physiological moisture