In winter, the low temperature, short sunshine and weak light cause the greenhouse vegetables to grow slowly, water consumption is small, the leaf evapotranspiration is small, and the soil water is scattered less. Therefore, there is a saying that the greenhouse vegetables are not watered for hundreds of days in winter. . Although this kind of statement has great one-sidedness, it is cold in winter and spring, and the water temperature is low. If water is frequently watered, the plants not only do not need to, but also cause harm, causing the ground temperature to drop, poor soil ventilation, and damaged roots. Absorption capacity is greatly reduced, and rooting occurs in a low-temperature, high-humidity environment. In addition, the winter and spring seasons are characterized by low temperatures and low ventilation. Frequent watering will not allow the humidity in the shed to fall for a long time. The â€œdew condensationâ€ time of the leaves is long, which creates conditions for the occurrence and spread of diseases. Therefore, the watering of greenhouses in winter must grasp the principle of â€œfive-to-five and no-floodâ€.
First, do not cast cloudy water: sunny watering, cloudy water. The specific watering time should be selected according to different weather conditions. Strictly abide by the watering on sunny days, little or no pouring on cloudy days, avoid the principle of watering on rain and snow days, especially in the cold and cloudy snow weather, you should try to avoid During this period of watering, so as to avoid causing the temperature drop caused by vegetable roots dead trees, or cause the air humidity in the shed to increase, resulting in the occurrence and spread of the disease. Watering time should be arranged on sunny days. After watering, it is best to have several consecutive sunny days.
Second, do not pour before pouring: Watering before noon and no water in the afternoon. Before the watering, the ground temperature recovered quickly and there was enough time to exclude the humidity in the shed. Don't water at noon so as not to affect the physiological function of the root when the water is heated. It is also not suitable to water in the evening so as to prevent the temperature in the shed from falling and then failing to recover. The death of the plants and the excessive humidity are also likely to cause serious vegetable diseases. Most vegetable farmers are now watering after 10 a.m., which is very inappropriate. Because when the weather is fine, the temperature of the shed is rising fastest after 9:00 am, and the temperature of the shed can reach 25Â°C at 10 o'clock. At this time, the ground temperature is not lower than 20Â°C. If this time watering, well water temperature is generally around 14 Â°C, well water temperature and ground temperature difference is too large, it is easy to cause rooting, dead tree phenomenon. In the morning, when the grass seed was just uncovered, the temperature of the shed was 13-15Â°C and the temperature was 10-12Â°C. If the water is poured at this time, the temperature of the well water is not much different from the ground temperature, and it is not easy to cause root damage after watering.
Third, pouring a small watering: pouring water, not flood irrigation. In winter, the temperature is low, evaporation is small, and the amount of water required for vegetables is also small. Therefore, the frequency of watering is small and the amount of watering is small. Under normal circumstances, the watering is the interline water, avoid bountiful irrigation, each time the amount of watering only 1/3 to 1/2 of the amount of water in summer. Such as overwintering cucumbers, when planting, large and small rows of ridge cultivation are adopted. Watering in the winter and spring seasons can be performed by watering the rows alternately, watering the small rows twice, watering the large rows once, and alternately irrigating the water to reduce the temperature of the groundwater. influences. Avoid flooding to prevent the spread of roots and diseases caused by low temperature and high humidity.
Fourth, do not cast water pouring cold: the water temperature is low in winter, watering the water to be first warmed in the shed, until the water temperature close to the ground temperature and then poured. Watering should use well water as much as possible, because the well water temperature is higher, which can reduce the physiological stimulation of vegetables. The temperature of the water should not be lower than 12Â°C. Never use the river water, reservoir water and cold water in the pond directly. After watering, turn off the ventilation openings even when the water is turned off, so that the temperature can reach and stabilize at 32Â° C. for 1 to 3 hours, increase the temperature in the greenhouse, promote the ground temperature with the air temperature, and promptly ventilate and exhaust the air after the ground temperature rises.
Fifth, pouring dark not poured: pouring dark water, not pouring water. The cultivation of vegetables in winter should insist on under-membrane irrigation. Under conditions, micro-irrigation under the membrane can be carried out. This can effectively prevent evaporation of ground water, reduce air humidity in the greenhouse, and prevent diseases. Especially in the deep winter season, the use of micro-irrigation has a positive effect on the balance and coordination of water, fertilizer, gas and heat required for vegetable growth. In particular, the use of micro-irrigation in the middle and early stages is conducive to root control and control of air humidity in the shed. , reduce the occurrence of pests and diseases. Micro-irrigation can also effectively control the amount of water, reduce the leakage of water in the deep layer and fertilizer loss, improve soil structure and performance, promote crop growth and improve vegetable quality.
In addition to the above five points, it should be noted that compound fertilizers with high nitrogen content must be used with caution, since the use of the compound fertilizers will reduce the water temperature and cause a significant decrease in ground temperature after watering. Therefore, it is necessary to apply more biological bacterial fertilizer and organic fertilizer in the deep winter to facilitate the improvement of the ground temperature.
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