1. Low-light barrier In low-light conditions, fruit development is inhibited, the weight of single fruit is reduced, and empty fruit and fruit rot are increased.
Preventive measures to improve lighting conditions in the shed as much as possible. When planting, increase the row spacing and reduce shading between the plants; keep the shed membrane clean and prevent the membrane surface from adhering to water droplets and dust; when the temperature reaches 15°C before and after noon in the middle and late stages of tomato growth, properly expose some of the shed film and let the sun shine. Directly into the shed. According to another test, a 2-meter-wide, 3-meter-long reflective screen made of polyester aluminized film was hung on the upper end of a post in a plastic greenhouse (or greenhouse) and hung down to the ground, adding 40 to 43% of light to the floor. The temperature increased by 3～4°C, the ground temperature increased by 1.8～2.9°C, the tomato yield increased by 41.8～58.1%, and the fruit quality was improved. The laying of silver ash film or aluminum foil on the ground could also increase the light intensity between the plants, so that the tomato could be well colored and could Prevent the premature decay of the lower leaves.
2. Low-temperature-tolerance tomatoes can't normally set fruit when the temperature is lower than 13°C. When the night temperature is lower than 15°C, they cause flowering and fruit drop. When the temperature is below 10°C, it is prone to cold injury. If the temperature is lower than 6°C, the plant will die. The low temperature duration is long, the leaves are dark green and dark, or the top bud growth point is frozen, the root growth is obstructed or malformed flowers are formed, causing low temperature drop or fruit malformation, and the fruit is not easy to be colored or lightly affected the commercial value.
Preventive measures: low-temperature exercise: After soaking, the seeds to be germinated will be frozen at a temperature of about 0°C for 1 or 2 days, and then sown to promote germination and enhance the cold resistance of the seedlings; the seeds to be germinated will be between 1 and 5 times a day. Placed at a lower temperature of °C for 12 to 18 hours, and then transferred to a higher temperature of 18 to 22 °C for 6 to 12 hours. Repeated for several days, it can also significantly improve the cold resistance of the seedlings and accelerate their growth and development. speed.
2 Before the planting, carry out the low-temperature hardening seedlings, choose sunny days when planting, in order to restore the growth of the root system.
3 The multi-layer covering of small arches in a plastic greenhouse can increase the temperature in small arches by 2 to 4°C over greenhouses and 1 to 2°C at low temperatures. In plastic greenhouses, two-layer curtains are made of plastic film and covered at night. The temperature and ground temperature in the shed can be increased by an average of 1 to 2°C. A layer of grasshoppers 1 meter high covering the greenhouse can also increase the temperature of the shed by 1 to 2°C.
4 Temporary warming Temporary warming equipment should be prepared as early as possible. Do not heat up and prevent carbon monoxide poisoning. The heating equipment should have a long flue with good heat dissipation to increase the utilization of heat energy.
5 According to the weather forecast, spray 80 to 100 times of 27% high fat film emulsion and 250 times of Bamlan's harvest liquid film in the evening. In addition, we must pay attention to the choice of low temperature resistant varieties, such as Tianjin Powder 65 and so on.
3. High-Temperature Barriers When the daytime temperature is higher than 35°C, or the high temperature of 40°C lasts for 4 hours, and the nighttime temperature is higher than 20°C, stem and leaf damage and fruit abnormalities will be caused.
Preventive measures 1 Ventilation reduces the temperature of the foliage.
2 shading. Strong sunlight can partially shade or shade the shade.
3 spray water cooling.
4. The tendon rot, also known as strip rot and stripe disease, is a common physiological disease in greenhouses (or greenhouses) in recent years. Sensitive fruits turn brown along the vascular part of the epidermis. The skin appears greenish due to delayed coloration; when the fruit is colored, internal browning can be seen from the outside. The cause of the rib rot disease is mainly the excessive application of nitrogen fertilizer, especially in the excessive application of ammonium nitrogen. In addition, the lack of light in the shed, the air does not circulate, irrigation is too much, the temperature is too high, the temperature difference between day and night is small, or the supply of nutrients such as potassium, boron, and calcium in the soil is insufficient, and tendon rot is easily induced.
Prevention measures Rational fertilization to prevent the single application of large amounts of nitrogen fertilizer; Diligent cultivation, less watering, keeping the soil loose, suitable moisture content, to promote root development, appropriate increase of lighting in the shed, and timely ventilation and prevent shed according to temperature changes in the shed The internal temperature is too high.
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