How to prevent and control acute dead cucumber seedlings in greenhouse

In the process of out-of-season cucumber cultivation covered with plastic film, when the cucumber enters the flowering and fruiting stage, there are often cucumbers which are growing well in the previous period, and the acute death of seedlings suddenly occurs within a few days. This kind of acute atrophy of cucumber occurs rapidly and is difficult to be prevented and treated. the causes are as follows: weather problems, continuous rain or steep sunshine after snow, temperature inversion leading to rapid death of seedlings; release problems, cucumbers enter the flowering and melon stage, sunny days with high temperature, large air volume, rapid foliar transpiration, some plants with poor roots begin to wither, and those with severe water loss wither. Chilling injury or freezing injury damaged part of the film surface of the greenhouse, and the cold wind caused wilting seedlings; the problem of excessive concentration of fertilizer, especially the application of chemical fertilizer near the stem base of cucumbers, was very easy to burn dead seedlings. Using greenhouse heat preservation cultivation places, cucumber acute atrophy occurs to varying degrees every year, in order to prevent it as soon as possible, the following measures should be taken. 1. The seedlings should be properly watered at the right time. The root system of cucumber is relatively developed, but it is mostly concentrated on the surface of the soil to produce new roots. It is necessary to avoid watering mistakes and restrain the growth of root populations, and pay attention to watering seedlings in time. Irrigate less fixed planting water, drink back to the seedling water. The temperature is low, the soil moisture is high, or encounter continuous rainy weather, less or no return seedling water. Enter the peak period of melon, combined with topdressing, water with fertilizer, irrigated every 10 days or so, strictly prevent excessive fertilization to burn melon seedlings. It is appropriate to water in the morning on a sunny day, and avoid watering in the afternoon and evening. It is not suitable to water the whole shed on cloudy and rainy days. Small water should be watered frequently, not flooding. 2. Control the temperature in the shed reasonably. At the initial stage of planting, it was generally not ventilated, keeping 25 ℃-30 ℃ in the greenhouse during the day and 12 ℃-15 ℃ at night, no less than 10 ℃. With the growth of melon seedlings, it is necessary to regulate gas and control temperature in time, and its functions are: preventing diseases, avoiding plant aging, and replenishing carbon dioxide. However, the regulation of temperature must be beneficial to the growth of cucumber. It is generally ventilated when the temperature rises to 30 ℃ in the daytime and closes the greenhouse film when it drops to 28 ℃ in the afternoon. The temperature during the melon setting period should not be lower than 12 ℃. Often dredge the ditches around the cucumbers planted in the shed to ensure smooth flow, so as to drain and irrigate in time and filter water quickly. Every day to check whether the greenhouse film is damaged or leaking cover, we should pay attention to repair, so as to keep warm and warm. Cover the grass and lock the rope before the strong wind cools down to prevent the cold wind from invading and injuring the melon seedlings.