When people eat cucumbers, they often experience bitter melons, which are more common in winter and spring. Bitterness seriously affects the quality of the cucumber. Bitterness is a physiological disease of cucumber caused by the accumulation of bittersin in cucumber. According to the survey, the incidence of cucumbers in greenhouses is often several times that of cucumbers cultivated in open fields. The correct use of the following methods can reduce or prevent the occurrence of bitter cucumbers. The selection of disease-resistant varieties for selection of disease-resistant varieties is one of the most cost-effective disease prevention measures. It is necessary to select varieties that do not produce bittersin. Practice has shown that the cucumber varieties such as Shandong Miaotong and Changchun Mickey are very easy to produce bittersin. On the other hand, cucumber varieties such as Jinza No.2, Jinza No.4, and Jinyan No.4 are not only high-yielding and high-quality, but also produce very few bitter melons. Therefore, it is a good choice to use resistant varieties. Regulate the humidity through the watering and adjusting the vents and other measures to regulate the greenhouse soil moisture and air humidity. Due to the fast growth and development of cucumber, thin and large leaves, high indoor temperature, and rapid evaporation of water, it must be timely watering, often maintaining adequate moisture and high air humidity, in order to meet the needs of cucumber growth and development. When the humidity is too low, physiological drought occurs in cucumbers, and drought can easily cause accumulation of bittersin. Watering should be timely and appropriate, should not flood flooding, so that "eat less meals," keep the soil dry and not wet, so that the relative humidity of the air, maintained at 75% in the morning, remained at 70% in the afternoon. If the indoor air humidity reaches more than 75%, it is necessary to use the high-temperature period before and after noon in order to promptly ventilate and dampen. Good temperature control studies have shown that bittersin is increased at temperatures below 13°C or above 30°C. To combine watering and adjusting vents and other measures, keep the temperature of the greenhouse at 25°C~30°C in the morning and 20°C~25°C in the afternoon. This will not only prevent the production of bitter, but also conducive to the growth and development of cucumber. There are too many nitrogen fertilizers for scientific fertilization, and insufficient phosphorus, potassium, and organic fertilizers can easily cause leggy seedlings, leading to poor reproductive growth and an increase in bittersin. According to the requirement of 5:2:6 ratio of nitrogen, phosphorus and potassium required for cucumber life, scientific fertilization is required. The quality farmyard fertilizer per hectare of basement is 5,000 to 6,000 kilograms, mixed with 50 kilograms of diammonium phosphate and 12 kilograms of potassium sulphate, and applied in the planting ditch to evenly mix the fertilizer with the soil. Fertilizer to control nitrogen fertilizer dosage at seedling stage, topdressing phosphorus and potash fertilizers to prevent plant growth; mid-term to increase the amount of nitrogen fertilizer, combined with the application of phosphorus and potassium fertilizers to meet the needs of a large number of flowering results; late spraying 0.3% of the phosphoric acid Potassium dihydrogen solution, once every 7 days, was sprayed 2~3 times. This fertilization can not only meet the needs of cucumber for nutrients, but also effectively prevent the production of bittersin. Proper dense planting density is too high, poor light transmission, will cause decreased photosynthesis, dry matter accumulation decreased, accumulation of bitter pigment increased. In order to improve the conditions for ventilation and light transmission, and to control the increase in bittersin, it is necessary to achieve proper close planting and carry out large and small rows of plants. At present, the varieties planted are 80 centimeters wide, 60 centimeters small, 30 centimeters long, and about 4,000 colonizations per acre are appropriate. To build scaffolds, tie vines and pick up cucumbers during the growth period should be based on the principle of increasing the light between the plants as much as possible. When the main vine grows to 30 to 35 centimeters, the first vines are tied, and then every 3 to 4 knots are tied together, and when the main vine climbs to the top of the rack, it picks up the heart. Topping the seeds can promote the fruiting of the vines, so as to control the length of the shoots, ensure good light transmission, improve the photosynthetic function of the leaves, and have a good effect on the prevention of bitterness. Spraying Rare Earth Microelement Fertilizers at the seedling stage, initial flowering stage and young stage of cucumber, spraying primary Rare Earth Microelement Fertilizer, can increase the photosynthetic efficiency of leaves, increase the disease resistance of leaves, control the production of bitter pigment, and increase the sugar content of cucumber. The amount of 1%-2% results in a significant increase in the yield and quality of cucumber. According to the experiment, spraying rare earth fertilization for 3 times can increase production by 5% to 6.8%. Premix Veterinary Medicine,Veterinary Multivitamin Premix,Veterinary Florfenicol Premix,Veterinary Oxytetracycline Premix Shandong Unovet Pharmaceutical Co.,Ltd. , https://www.unovetcn.com