How to keep warm in vegetable greenhouse in winter

First, raise seedlings in a nutrition bowl. The black plastic nutrition bowl has the function of absorbing heat during the day and protecting the roots at night. When the external air temperature is about 10 ℃, the temperature in the border is 6 ~ 7 ℃, and the temperature in the nutrition bowl is about 10 ℃. The seedlings can grow slowly and not be damaged by freezing.

Second, cultivate hot nutrient soil. Chicken dung is hot dung, and cow dung is breathable manure rich in mucus. After the two are mature, each of them takes 20%, and 60% of the soil is mixed with Yang soil. The nutritive soil has good heat absorption and heat generation performance, good seedling ecological environment, large and long root system, strong absorption capacity, and natural freezing resistance of the plant.

Third, irrigate the roots with rooting element when dividing the seedlings. Rooting element is reasonably prepared with calcium, phosphorus, zinc and other nutrient elements related to long roots. Calcium determines the thickness of roots, phosphorus determines the number of roots, and zinc determines the growth rate and length of roots. After use, the roots can be increased by about 70%, deep roots by 25%, roots developed, absorption capacity increased by about 70%, deep roots by 25%, absorption capacity increased by about 70%, deep roots by 25%, developed roots and strong absorption capacity, so that seedlings will not be frostbitten due to poor cold resistance caused by lack of water and elements.

Fourth, foliar spraying nutrients to resist cold. In the severe cold winter, the temperature is low and the light is weak, the absorption capacity of the root system is weak, and spraying micro-fertilizer on the leaf surface can supplement the deficiency of the root system caused by insufficient absorption of nutrition. Foliar spraying rice vinegar can inhibit bacteria and disinfect insects, and when mixed with white sugar and calcium superphosphate, it can increase the sugar content and hardness of mesophyll and improve cold resistance. The leaf surface showed alkaline atrophy after frost injury and air injury. Spraying vinegar can alleviate the damage degree, and 100-300 times liquid should be used. Use little or no growth hormones to prevent cold resistance.

Fifth, enough water to keep warm and prevent frost damage. The specific heat of water is higher than that of air, the heat dissipation is slow, the water content of indoor soil is moderate in winter, the pore cracks of tillage layer are fine, the root system is not suspended, the soil is insulated, and the root system is not damaged by freezing. Therefore, the freezing injury of seedlings is mostly caused by lack of water, so pouring enough water before winter or choosing a good weather (more than 20 ℃ can be watered) can prevent frost injury.

Sixth, ploughing, heat preservation and cold protection. The ground is hardened, the entry of hot air into the tillage layer is limited during the day, the soil heat storage is less, coupled with the large and deep cracks in the consolidated soil, poor aggregate structure, easy to lose heat 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 ploughing can break the cracks in the ground, which can not only control groundwater transpiration and take away heat energy, but also preserve soil moisture, heat preservation and cold protection.

Seventh, keep watch on sunny days. The external temperature of the standard greenhouse with good seedling performance is about-10 ℃, and the highest indoor temperature in the morning on a sunny day in winter can reach more than 32 ℃. Many people think that this is the best time for long freezing and temperature promotion, so it is not suitable to keep out the wind. In fact, the air should be released repeatedly at this time to reduce the temperature difference between indoor and outdoor, which is close to the room temperature a few days ago, so that the plant can slowly adapt to the environment and grow healthily. Beware of sudden growth in one day and cold in ten days, resulting in flashing seedlings and freezing injury.

Eighth, replenish carbon dioxide. The yield-increasing effect ratio of carbon and ammonia to crops is 1 ∶ 1, and the requirement of crops for carbon-nitrogen ratio is 30 ∶ 1. At present, most farmers recognize the yield-increasing effect of nitrogen, but ignore the yield-increasing effect of carbon. Greenhouse vegetables are easy to grow and yellowed in winter. the carbon dioxide produced by crop respiration and soil microbial decomposition at night can be absorbed one hour after sunrise, and the greenhouse film can be opened and closed at about 12:00, and the greenhouse film can be opened and closed when the temperature is high. put carbon dioxide into the outside world to improve resistance and yield. Closing the shed when the temperature is low and artificially replenishing carbon dioxide can enhance the cold resistance of crops and greatly increase the yield.

9. Cover and keep warm in time. The wall is generally 1 meter thick. Heat absorption and storage temperature during the day, energy release at night accounts for 50% / 60% of the total indoor heat, soil heat absorption and heat release accounts for 20% / 30%, and space heat storage accounts for 20% / 30%. According to the winter and current temperature, the room temperature may be kept at about 18 ℃ an hour after the cover. If it is higher than 18 ℃, it can be covered later, and if it is lower than 18 ℃, it will be covered earlier.

10. The rear wall is heated by a reflective film. Greenhouse vegetable production in winter, not afraid of cold, afraid of light, afraid of even cloudy days. Therefore, before and after the Winter Solstice, hanging a plastic film reflection on the back wall can improve the light intensity of the cultivation bed, slowly release the heat energy stored in the wall indoors at night, maintain a higher temperature in the middle of the night, and prevent the seedlings from freezing injury.