In greenhouse cultivation of cucumbers, after entering April, as the temperature gradually increases, if the ventilation is not timely or the ventilation is not smooth, the temperature in the greenhouse can sometimes reach as high as 40-50°C, and sometimes it can reach as high as 50°C or more in the afternoon, which may cause growth of cucumbers. Development damage, light plants wilting to stop growing, in serious cases the whole plant leaf wilting, has a great impact on the yield and quality of cucumber.
Symptoms When the seedlings encounter high temperatures, the seedlings appear cropped, small cotyledons, drooping, and sometimes flowering; seedlings encounter high temperatures, light leaf color, large and thin leaves, do not stretch, internode elongation or leggy In adult plants, the chlorotic spots of 1~2mm near-circular to elliptic were first appeared on the leaves, and then gradually expanded. After 3~4d, the leaves and veins of the whole plant turned green and yellow from top to bottom. The onset was severe in the upper part and the plants stopped growing when severe. When the temperature in the greenhouse reaches 48°C, the leaflets near the growth point of the cucumber will be wilted and the leaf margin will be dark within a short time. When the time is long, the whole leaf is wilting, such as hot water.
One of the reasons is the lack of cucumber cultivation experience, the management of cucumber growth temperature is not clear, that cucumber is a kind of thermophilic vegetables, so blindly to the pursuit of high temperatures, resulting in the greenhouse temperature exceeds the appropriate temperature for its growth Causes high temperature barriers.
Second, under normal circumstances, due to people's attention to temperature management, it will not cause thermal damage in the greenhouse. However, due to the low temperature in the previous year, workers may neglect cooling and wait until noon and afternoon temperatures in the greenhouse. Suddenly rising to 48°C, the relative humidity of the air is reduced. If the duration is short, the leaves are injured. If the time is too long, the whole plant will die.
Prevention methods ◎ strengthen ventilation. Every stage of cucumber has its proper temperature. When raising the seedlings, the temperature in the bed should be maintained at 25 to 30°C during the day and at 16 to 18°C ​​during the night; after 80% of the seedlings are unearthed, the temperature must be reduced in time, during the day at 20 to 25°C, and at night at 14 to 16°C; During the day, the temperature reaches 30-35°C, and the temperature is not lower than 18-16°C at night. After the seedlings are slowly grown, the room temperature reaches about 30°C during the day and 16-14°C at night; during the melon period, the shelf temperature is maintained at 28-30°C during the day. , control at 16 ~ 18 °C at night, relative humidity below 85%. In production, the temperature gauge should be read at any time to grasp the temperature changes. When the temperature is slightly higher, the greenhouse door and vents can be used to cool the air. If the temperature is still high, then the bottom of the south side must be opened so that The temperature of the shed is lowered, and at the same time, attention should be paid to watering, preferably from 8 to 10 o'clock in the morning. Do not water at night or on cloudy days. Also note that the difference between the water temperature and the ground temperature should be below 5°C.
◎ The relative humidity of cucumber in the appropriate period of growth is about 85%. When the relative humidity of the greenhouse is higher than 85%, it should be ventilated and dehumidified; when the temperature is 18 to 20°C in the evening, it should be ventilated for 1 hour to reduce the humidity at night so as to prevent “extreme length†and avoid high temperature obstacles.
â—Ž Due to the high temperature, the plants are too long. In production, the plants can be forced to suppress their leggy so as not to cause excessive growth. For this reason, 100% liquid can be used to spray flowers or flowers, can promote early maturation and prevent leggy.
â—Ž Appropriate application of phosphorus and potassium fertilizers can also be sprayed with multiple organic active liquid fertilizers or potassium dihydrogen phosphate 0.2% solution or 0.1% urea solution for extra-root dressing 2 or 3 times to effectively improve the plant's resistance to heat.
â—Ž In case of persistent high temperature or atmospheric drought, cucumbers in the greenhouse have large evaporation and strong respiration. At this time, the water consumption is very large. If the duration is long, there will be snoring and other phenomena. In this case, the number of waterings should be appropriately increased and the water should be poured once. Penetrate once more every two days, so that the seedlings fully absorb enough water.
Author: Hebei City, Hebei City Agricultural Technology Promotion Center
Symptoms When the seedlings encounter high temperatures, the seedlings appear cropped, small cotyledons, drooping, and sometimes flowering; seedlings encounter high temperatures, light leaf color, large and thin leaves, do not stretch, internode elongation or leggy In adult plants, the chlorotic spots of 1~2mm near-circular to elliptic were first appeared on the leaves, and then gradually expanded. After 3~4d, the leaves and veins of the whole plant turned green and yellow from top to bottom. The onset was severe in the upper part and the plants stopped growing when severe. When the temperature in the greenhouse reaches 48°C, the leaflets near the growth point of the cucumber will be wilted and the leaf margin will be dark within a short time. When the time is long, the whole leaf is wilting, such as hot water.
One of the reasons is the lack of cucumber cultivation experience, the management of cucumber growth temperature is not clear, that cucumber is a kind of thermophilic vegetables, so blindly to the pursuit of high temperatures, resulting in the greenhouse temperature exceeds the appropriate temperature for its growth Causes high temperature barriers.
Second, under normal circumstances, due to people's attention to temperature management, it will not cause thermal damage in the greenhouse. However, due to the low temperature in the previous year, workers may neglect cooling and wait until noon and afternoon temperatures in the greenhouse. Suddenly rising to 48°C, the relative humidity of the air is reduced. If the duration is short, the leaves are injured. If the time is too long, the whole plant will die.
Prevention methods ◎ strengthen ventilation. Every stage of cucumber has its proper temperature. When raising the seedlings, the temperature in the bed should be maintained at 25 to 30°C during the day and at 16 to 18°C ​​during the night; after 80% of the seedlings are unearthed, the temperature must be reduced in time, during the day at 20 to 25°C, and at night at 14 to 16°C; During the day, the temperature reaches 30-35°C, and the temperature is not lower than 18-16°C at night. After the seedlings are slowly grown, the room temperature reaches about 30°C during the day and 16-14°C at night; during the melon period, the shelf temperature is maintained at 28-30°C during the day. , control at 16 ~ 18 °C at night, relative humidity below 85%. In production, the temperature gauge should be read at any time to grasp the temperature changes. When the temperature is slightly higher, the greenhouse door and vents can be used to cool the air. If the temperature is still high, then the bottom of the south side must be opened so that The temperature of the shed is lowered, and at the same time, attention should be paid to watering, preferably from 8 to 10 o'clock in the morning. Do not water at night or on cloudy days. Also note that the difference between the water temperature and the ground temperature should be below 5°C.
◎ The relative humidity of cucumber in the appropriate period of growth is about 85%. When the relative humidity of the greenhouse is higher than 85%, it should be ventilated and dehumidified; when the temperature is 18 to 20°C in the evening, it should be ventilated for 1 hour to reduce the humidity at night so as to prevent “extreme length†and avoid high temperature obstacles.
â—Ž Due to the high temperature, the plants are too long. In production, the plants can be forced to suppress their leggy so as not to cause excessive growth. For this reason, 100% liquid can be used to spray flowers or flowers, can promote early maturation and prevent leggy.
â—Ž Appropriate application of phosphorus and potassium fertilizers can also be sprayed with multiple organic active liquid fertilizers or potassium dihydrogen phosphate 0.2% solution or 0.1% urea solution for extra-root dressing 2 or 3 times to effectively improve the plant's resistance to heat.
â—Ž In case of persistent high temperature or atmospheric drought, cucumbers in the greenhouse have large evaporation and strong respiration. At this time, the water consumption is very large. If the duration is long, there will be snoring and other phenomena. In this case, the number of waterings should be appropriately increased and the water should be poured once. Penetrate once more every two days, so that the seedlings fully absorb enough water.
Author: Hebei City, Hebei City Agricultural Technology Promotion Center
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