Techniques of planting out-of-season vegetables in vegetable greenhouses

Producing out-of-season vegetables in winter is one of the effective ways to ensure the annual vegetable supply. Mainly refers to the spring and summer vegetables postponed in autumn and produced in advance in spring. Cold-proof measures must be taken when planting to achieve the purpose of early listing.

(1) site selection

In areas where vegetables are produced out of season in winter, it is required to choose places with warm climate, abundant sunshine, low altitude or hills in plain areas, convenient water sources, suitable soil conditions and wind barriers (such as mountain barriers or other buildings in the north) to avoid direct attacks by cold air.

(2) Variety selection

Cold-resistant, disease-resistant and early-maturing varieties should be selected for off-season vegetable production in winter, and autumn-delayed varieties should also be heat-resistant at seedling stage. For example, there are Update No.4, Update No.5, Xiang Yan No.9, Xiang Yan 10, Xiang Yan 1 1, Guangjiao No.2, Layou No.4, Eggplant Fengqie 1 and Fengqie No.2, Cucumber Jinza No.3, Jinza No.4 and Jinchun No.4.

(3) High-quality and efficient cultivation techniques

1, greenhouse vegetables keep warm and cold in winter.

Seedling raising in nutrition bowl: The black plastic nutrition bowl has the functions of absorbing heat during the day and protecting roots at night. When the outside temperature is about-10℃, the temperature in the border is about 6 ~ 7℃, and the temperature in the nutrition pot is about 10℃, the seedlings grow slowly and will not be frozen. ?

Preparation of hot nutrient soil: chicken manure is hot manure, cow manure is breathable manure and rich in mucus. After they are decomposed, 20% is taken away and 60% is mixed with fine soil. This nutrient soil has good heat absorption and power generation performance, good seedling ecological environment, developed root system, strong absorption capacity and strong plant frost resistance. ?

Root irrigation with rooting element during seedling division: Rooting element is reasonably prepared from several nutrient elements related to long roots, such as calcium, phosphorus and zinc. Calcium determines the thickness of roots, phosphorus determines the number of roots, and zinc determines the growth speed and length of roots. After using rooting agent, the root system can be increased by about 70% and the deep root can be increased by 25%. The root system is developed and the absorption capacity is strong, and seedlings and vines will not be frostbitten because of poor cold resistance caused by lack of water and elements. ?

Adequate water for heat preservation and antifreeze: the specific heat of water is higher than that of air, and the heat dissipation is slow. In winter, the indoor soil moisture content is moderate, the pore cracks in the plough layer are fine, the roots are not suspended, the soil is warm, and the roots are not damaged by freezing. Therefore, the frost damage of seedlings is mostly caused by lack of water. Therefore, pouring enough water before winter or when the weather is fine (watering above 20℃) can prevent freezing injury. ?

Heat preservation and cold protection of intertillage: the ground is hard, and hot air is restricted from entering the plough layer during the day, so the soil stores less heat energy. In addition, the hardened soil has large and deep cracks, poor aggregate structure, easy heat dissipation in the first half of the night, and low room temperature in the second half of the night, which is easy to cause freezing damage. Shallow intertillage can break the ground and close the seam, which can not only control the transpiration of groundwater to take away heat energy, but also keep moisture, keep warm, prevent cold and protect seedlings. ?

Spraying nutrients on leaves to resist cold: the temperature is low in winter, the light is weak, and the absorption capacity of roots is weak. Spraying photosynthetic micro-fertilizer on leaves can supplement the element deficiency caused by insufficient absorption of nutrients by roots. Spraying rice vinegar on leaves can inhibit bacteria and repel insects, and mixing with white sugar and calcium superphosphate can increase the sugar content and hardness of mesophyll and improve the cold resistance. After freezing injury, the leaf surface is alkaline atrophy, and spraying vinegar can reduce the degree of injury. It is advisable to use 100 ~ 300 times liquid, and use less or no growth hormone to prevent the cold resistance from decreasing.

Repeated drying in sunny days: the maximum temperature in the shed can reach above 32℃ in sunny morning in winter. At this time, it is necessary to dry it repeatedly, reduce the temperature difference between indoor and outdoor, and let the plants slowly adapt to the environment and grow healthily. Beware of sudden growth in one day and sudden cold in ten days, causing flash seedlings and freezing damage. ?

Supplementing carbon dioxide: the ratio of carbon and nitrogen to crop yield is 1: 1, and the demand for carbon and nitrogen ratio is 30: 1. At present, most farmers have realized the influence of nitrogen on crop yield, but neglected the influence of carbon on crop yield. In winter, vegetables in greenhouses grow yellow easily. The carbon dioxide produced by crop respiration and soil microbial decomposition at night can be absorbed after the sun comes out 1 hour, and it will be in a state of carbon hunger about 12 hours. When the temperature is high, the greenhouse film can be opened and closed to release external carbon dioxide and improve resistance and yield. When the temperature is low, closing the greenhouse and artificially supplementing carbon dioxide can enhance the cold resistance of crops and greatly increase the yield. ?

Cover in time to keep warm: in general greenhouses, heat is absorbed and stored during the day, and energy is released at night, accounting for 50% ~ 60% of the indoor total; Soil heat absorption and release accounts for 20% ~ 30%; Space thermal storage accounts for 20% ~ 30%. Depending on the temperature of the day, after covering 1 hour, the room temperature may remain around 18℃. It can be covered later when it is higher than 18℃, and earlier when it is lower than 18℃.

Selection of straw mulch: the thermal conductivity of straw mulch is lower than that of cattail mulch, and it has good cold resistance. In addition, the soft and compact texture of straw mulch can reduce heat loss and increase the lowest indoor temperature by 2 ~ 3℃ at night.

Covering with multilayer film for heat preservation: raising seedlings in greenhouse, covering the seedbed with film, then supporting a small arch shed at the height of 1 m, and covering a film outside the small arch shed or 20 cm away from the greenhouse at night. In this way, various seedlings can be cultivated without heating. After planting, cover the ridge with plastic film, keep moisture, control humidity and raise the temperature, but don't seal the ground too tightly, leaving 15 ~ 20 cm, so that the heat energy stored in the soil can slowly radiate to the space through the bare ground at night, and the minimum temperature will increase 1 ~ 2℃ at 5 ~ 7 in the morning. Cover the grass with a film, or support a film 20 cm away from the film to form an insulation layer, which can increase the room temperature by 1 ~ 3℃. ?

Choose purple film: The ultraviolet in the solar spectrum in winter is only about 5% of that in summer. The white film can't penetrate ultraviolet rays, but the purple film can. Ultraviolet spectrum can inhibit diseases and sterilization, control plant overgrowth and promote nutrient accumulation. The room temperature of purple film is 2 ~ 3℃ higher than that of green film in winter.

There is a professional book "Off-season Vegetable Planting Technology".