当大棚保护地内的最低温度低于蔬菜正常生长所需要的最低温度时,植株就会表现出一系列的症状,从而影响植株的生长发育,造成较大的经济损失。所以早春遇寒流、连阴天来临,要创造出适宜蔬菜生长发育的温度条件,防止出现低温危害。症状的主要表现为:当发生冻害时,冻害植物体内水分结冰,致使细胞组织死亡。轻者仅有部分叶片受冻,重者则大部分叶片被冻死。冷害,又称寒害、低温障碍。它是由于棚室内的温度长时间低于蔬菜生长的最适宜温度时,植株出现萎蔫、生长缓慢; When the minimum temperature in the greenhouses is lower than the minimum temperature required for the normal growth of vegetables, the plants will exhibit a series of symptoms, which will affect the growth and development of plants and cause greater economic losses. So early spring when the storm, even the cloudy advent, to create a suitable temperature for vegetable growth and development, to prevent the occurrence of low-temperature damage. Symptoms of the main manifestations are: When the occurrence of frost damage, frost damage to plants in the water freezing, resulting in cell death. Only part of the light leaves were frozen, and most of those leaves are mostly frozen to death. Cold damage, also known as cold damage, low temperature disorders. It is due to greenhouse temperature for a long time lower than the optimum temperature for vegetable growth, plant wilting, slow growth;