Eight key points of vegetable cultivation techniques in greenhouse 1. The total soil salt required for the normal growth of greenhouse vegetables by balanced fertilization is 2000~3000 mg/kg. When it exceeds 6500 mg/kg, the root system will appear reverse osmosis and die, and the yield will naturally decrease. The greenhouse has high temperature and humidity, and the organic fertilizer decomposes quickly, and the availability of phosphorus is 2~3 times higher than that in the open air. The volatilization of nitrogen is large, and excessive fertilization is easy to cause fertilizer damage. In the greenhouse, more phosphorus and potassium fertilizers should be applied, less nitrogen fertilizers should be applied, and cake fertilizer, human excrement and urine, and immature green manure straws should not be applied. Topdressing should be "eat less and eat more meals" to prevent the concentration from being too high. Generally, the cow dung of greenhouse chickens planted for more than three years is controlled within 2500 kg each, and the chemical fertilizer is reduced by about 50%. For plots with high total salt concentration, pay attention to the application of organic cattle fertilizer, humic acid fertilizer and EM bacterial fertilizer, improve soil carbon-nitrogen ratio, loosen soil ventilation, dissolve salt and reduce fertilizer damage. At the same time, boron, zinc and magnesium are supplemented to balance soil nutrition. Second, the number of seedlings left in greenhouse vegetables with dense seedlings directly affects the yield. According to the measurement, two tomatoes with 1 m2 consume 50% of photosynthetic products and get 50% of fruits. If four trees are planted per square meter, the vegetative body consumes 70%~80% of photosynthetic products, and the products can only account for 20%~30%. On the contrary, close planting will lead to low yield, plants will grow up in vain because of the competition for sunlight, and it is easy to be infected with various mycoses and bacterial diseases due to poor ventilation. At the same time, in winter, the temperature is low, the light is weak, the photosynthesis is poor, and the carbohydrate synthesis is less, so it must be planted thinly. Generally, close planting in the early stage, thinning plants in the middle stage and thinning branches in the later stage, with the principle of not crowded branches and leaves, make full use of space and improve the total output and benefit of greenhouse. Third, the prevention and management of vegetable vines in greenhouses Generally, the seedlings are weak and the roots are deep. It is necessary to control water and plants to promote roots, so that the underground part absorbs about 60% of photosynthetic products, and the underground and aboveground absorption accounts for 50% in the middle and late stages. In the early stage, plants consume 60% of nutrients, and reproductive growth accounts for 40%. 50% in the medium term; Late reproductive growth accounts for 60%~70%, and vegetative growth only accounts for 30%~40%. That is to say, ensure a certain assimilated leaf area in the early stage, control vines to promote fruit and increase yield in the later stage. Too many vines will inevitably affect the nutrient accumulation of products, and the consumption of photosynthetic products will be high and the yield will be low. So vine overgrowth is not a good vegetable. Fourth, scientifically fight drugs to treat diseases At present, the main way for vegetable farmers to solve vegetable pests and diseases in greenhouses is to fight drugs, but how to fight drugs well is also very particular. First of all, we should make clear the symptoms and choose the appropriate drugs. Generally, chemicals containing copper and zinc should be selected, which can not only sterilize, but also enhance the ability of plants to resist the invasion of germs and promote crop growth. Second, improving the ecological environment, reducing the humidity in the shed, such as drip irrigation under the film, reducing the number of plants, enhancing ventilation and light transmission, can reduce pests and diseases and reduce the amount of pesticides. Thirdly, seedling death caused by soil-borne bacteria should be prevented by medication at seedling stage. If it is not solved well in the early stage, it will occur in the seedling stage and attack in the later stage. Germs and bacteria have invaded the plants, and the effect of diligent application is not good. 5. Rational use of "greenhouse gases" in the process of greenhouse vegetable planting, especially in winter and spring, it is easy to produce harmful gases because it is sealed for a long time, which is harmful to greenhouse vegetables. For example, when nitrate nitrogen fertilizer and immature organic fertilizer are applied to greenhouse soil, a large amount of nitrous acid gas will be produced during decomposition and decay. When it reaches a certain concentration in the greenhouse, it will hurt solanaceae vegetables, make the leaves on the ground burn like boiling water, and in severe cases, the mesophyll will turn white and die. At the same time, greenhouse vegetables are particularly short of carbon dioxide under the irradiation of morning sunlight. Therefore, in winter and spring, for all kinds of vegetables digested overnight, adding appropriate amount of carbon dioxide gas fertilizer between the sun exposure the next morning can make vegetables grow fast, prolong the growth period and increase the yield. When the temperature is high at noon, open the ventilation vent regularly to reduce gas damage. 6. Drip irrigation under plastic film solar greenhouse belongs to a closed and semi-closed environment, and the evaporation and diffusion of water are slow. Generally, the transpiration of plants and the evaporation of soil moisture are only 50% of those in the open field, especially at night, on cloudy days and when the temperature is low, the relative humidity of the air is often saturated. Excessive humidity in greenhouse is the main cause of vegetable diseases. If drip irrigation under film is used to irrigate greenhouse vegetables instead of flood irrigation, the greenhouse environment can be greatly improved, the humidity can be reduced, the greenhouse temperature can be increased, the vegetable diseases can be reduced, and the purpose of increasing production and improving quality can be achieved. Greenhouse vegetables are covered with plastic film. According to the measurement, the indoor humidity before plastic film mulching can reach 95%~ 100% at night, and it will drop to 75%~80% after plastic film mulching. The incidence of drip irrigation under film is lower than that of flood irrigation 10%~ 15%, saving water by 60% and increasing yield by 40%. Therefore, drip irrigation under plastic film is the most ideal irrigation method for greenhouse vegetables. Seven, arrange the appropriate number of stubble. Many vegetable farmers believe that it takes a lot of money to build a greenhouse, and the land cannot be idle all the year round, so the main stubble is covered with a second stubble, which is the same as the main stubble. The result is not as good as 25 10. In fact, it is better to plant one crop a year after the long winter, and two crops a year in spring and autumn. Old plants of eggplant, pepper, tomato and cucumber can be regenerated for one crop, and seedlings should be left to dry when the price is low. Leave a period of time in summer to dig deep into the rain to suppress salt, sterilize in the sun, close the shed to kill insects, and solidify the soil, and the main crop problem will be less, and the income will be several thousand yuan or even ten thousand yuan. Eight, master the greenhouse temperature Many vegetable farmers believe that the higher the greenhouse temperature, the faster the vegetables grow. Actually, it's not. There is an upper limit for the maximum temperature of vegetable growth, that is, the maximum temperature is 25℃~30℃. For different vegetables, the maximum temperature is different. The optimum temperature of warm cucumber and eggplant is 25℃~32℃, and the suitable temperature of cold-resistant vegetables such as celery and leek is 15℃~22.