随着近年来西瓜保护地栽培的发展,各地应用塑料大棚、塑料小棚等保护设施进行早熟西瓜栽培也越来越多,并且取得了明显的经济效益。但是保护地栽培由于受到科技发展水平和自然条件的限制,北方地区在3～4月如果遇到连续阴雨天气,在苗床或在其它保护地条件出现低温、弱光等不利情况下,将导致西瓜幼苗生长出现抑制。其主要表现为,新蔓与幼叶生长明显变缓甚至停止,严重者幼苗的生长点弯曲并消失,呈现自封顶现象。 保护地栽培的西瓜幼苗生长点消失现象,因不同品种、低温弱光等逆境的程度和栽培管理条件的区别而有所差异。一般在1～2片真叶期,当设施内夜间气温低于15℃时,西瓜幼苗就会出现矮化和生长停止现象,低于10℃～13℃时有些品种开始出现生长点消失现象。这种现象在中晚熟大果型品种往往比早熟品种严重,因为大果型品种生长通常需要比早熟品种更高地温度和光照强度,因此也就更加容易受到低温和 With the development of cultivation of watermelon protected areas in recent years, the application of plastic greenhouses, plastic sheds and other protective facilities to carry out precocious watermelon cultivation is also more and more, and has achieved obvious economic benefits. However, cultivation in protected areas is limited by the level of technological development and natural conditions. If it encounters continuous rainy weather from March to April in the north, adverse conditions such as low temperature and poor light in the seedbed or other protected areas will result in watermelon Seedling growth appears to be inhibited. The main manifestations of the new vine and young leaf growth significantly slowed down or even stopped, in serious cases, the growth point of seedlings bent and disappeared, showing self-captive phenomenon. The disappearance of growth point of cultivated watermelon seedlings in protected area may be different due to the differences of the adversities of different cultivars, low temperature and poor light, and the cultivation and management conditions. Generally in 1 ~ 2 true leaf stage, when the night temperature in the facility is lower than 15 ℃, dwarfing and growth arrest will occur in the watermelon seedlings. When the temperature is below 10 ℃ ~ 13 ℃, some species begin to disappear. This phenomenon tends to be more severe in medium to late-maturing large fruit varieties than in early-maturing varieties, as large fruit varieties generally require higher temperature and light intensity than the precocious varieties and therefore are more susceptible to low temperature and