Winter and spring seasons are low temperatures, short sunshine, and weak light. These natural conditions are important factors influencing the formation of strong seedlings. However, under the current production level conditions, it is difficult to solve the problem fundamentally, especially in the lighting conditions. Therefore, in the winter and spring nursery season, if the management is not good, the melon seedlings are prone to two situations: one is the aging seedlings, and the other is the long seedlings. The so-called aging seedlings are that the calendar seedling age (days) does not match the physiological seedling age (size). Under normal conditions, the physiological seedling age is four-leaf, and the calendar seedling age is about thirty days. If the seedlings of the 30-day breeding are only two-three leaflets, and the short internodes are short and the roots are underdeveloped, they are called "aging seedlings". Or called "small old seedlings." The main reason for the formation of "aging seedlings" in the spring season is the low temperature, especially the lower night temperature. The ground temperature is often below 12 degrees, the root absorption capacity is weak, and the amount of growth in the shoots is small. Low temperature is the main contradiction affecting the growth of seedlings. As long as the temperature rises, the problem will be solved. The so-called long seedlings are seedlings that are large and thin, with pale green color, long internodes, poor root development, late melons, thin melons, weak disease resistance, and difficult to produce high yields. The main reason for the cause of the seedlings is that the light is weak. Some greenhouse nurseries, small arch sheds on the seedbed, no film is exposed during the day, causing only 30% of the natural light in the seedbed; some use old membranes, the membrane is seriously polluted, and it is exposed for six hours in time. . In the late stage of nursery, the branches and leaves are mutually occluded, which is also an important reason for the formation of long seedlings. In the case of short illumination time and weak illumination, if the soil moisture is increased, the temperature difference between day and night is small, and the seedlings are more likely to grow. 4 Wire Intercom Villa,Analog System 4 Wire Intercom Villa Video Doorbell,4 Wire Intercom System Villa,4 Wire Intercom Video Doorbell Villa Single House Zhuhai Mingke Electronics Technology Co., Ltd , https://www.mingke-tech.com