From mid-June to July of each year, due to the northern jump of the Pacific subtropical high and control of Guangdong Province, the precipitation is relatively reduced and the light is intense. Sunny and hot weather often occurs, affecting the normal flowering grouting of early rice. This is the case with the “high-temperature ripening†of the agricultural reclamation. The suitable humidity for early rice grouting is 25-28 degrees. Higher than 32 degrees has a bad influence. High humidity at 35 degrees has a significant effect. If air drying is added, the impact on early rice is even greater. (a) What is called high-temperature heat damage? High-temperature damage to crop growth and production, known as high-temperature heat damage. Early rice in Guangdong, during flowering and grouting, is often affected by high temperatures, which raises the temperature of the leaves, reduces the photosynthesis ability of the leaves, increases the respiration rate of the plants, decreases the level of material supply, and causes high temperature and heat damage during early flowering and may cause pollen Starch accumulation of granules is not sufficient, so that the cracking of anthers is inhibited, and pollination is not normal. As the temperature rises, the early flowering peak period of early rice affects the fertilization process and forms empty shells; the early rice filling stage suffers from high temperature and low humidity, which may easily cause the leaves. Withered yellow, the whole grain filling period is shortened, grain filling is not sufficient, and thus the seed setting rate and 1000-grain weight are reduced. Experiments show that the most obvious decline in seed setting rate is the occurrence of high-temperature heat damage weather within 6-10 days after flowering; the most reduction in 1000-grain weight is encountered in high-temperature dry weather within 11-15 days after flowering; Carbohydrates (photosynthetic products) are prematurely attenuated or stopped transiting into the panicle grains, thus resulting in a decrease in the 1000-grain weight and an increase in impractical grains. High temperature intensity, duration time, and temperature difference between day and night all have a direct impact on the open space rate. Different varieties of rice or the same variety have different resistance to high temperature at different developmental stages; the degree of damage is also related to seedling quality, plant growth status, cultivation conditions, and management level. (2) Damage index of high-temperature heat damage The indicator of high-temperature heat damage is that the daily maximum temperature is above 35 degrees for more than 3 days, and the sensitive period is at the flowering stage of rice. Practice has shown that in the flowering period, high temperatures above 35 degrees for one hour will cause high infertility of spikelets, among which flowers that are being opened are most affected. (3) Measures to prevent heat damage at high temperatures generally adopt four measures: avoidance, rectification, prevention, and anti-inflation. Avoid: In order to reduce and avoid the threat of high temperature and heat damage, we can reasonably arrange early rice production according to the local climate law of high temperature, select high-quality, high-yield and high-quality varieties that are resistant to high temperature and heat damage, and arrange suitable sowing and cutting periods so that the key growth period of early rice can be avoided. High temperature heat damage. Change: Use high-quality, high-yield and high-temperature resistant varieties, build farmland shelterbelts, improve the ecological environment of rice fields, improve soils, and increase soil water storage and water retention capacity. Improve water conservancy grouting facilities and increase the ability to resist high temperature and drought. Prevention: Before the high temperature season arrives, the Tangba Reservoir will store good water to prevent high temperature dehydration. Increasing fertilizing materials, controlling the growth and growth of early rice, and improving the ventilation and light transmission conditions between the flowering and the beginning of filling can reduce the high temperature and heat damage. For the seedlings with insufficient stamina, when the last one is fully developed, urea is applied at 2 kg to 2.5 kg or 400-500 kg of vegetation ash per acre. Spraying fertilizer with urea, superphosphate, etc. during flowering to grain filling also helps to increase the seed setting rate and 1000-grain weight. Anti-inflammation: that is, taking measures during the high temperature, mainly scientific management, seeing the irrigation, cooling and humidifying with water. (1) Flowering to filling stage: The groundwater should be grounded in shallow water, filled with night water, and drained at the right time to prevent premature water cut, so as to improve the microclimate of paddy fields, promote strong root systems, and enhance the ability to resist high temperatures. Deepening the water layer at high temperature during the day can reduce the spikes by 1-2 degrees. When the high temperature and drought are combined, the body temperature can be reduced and the temperature between the plants can be increased. Day irrigation night row can increase the temperature difference between day and night, the effect is better. According to experiments, the temperature difference between day and night increases by 1 degree, and the grain weight can increase by 0.5-1 grams. (2) Sprinkler irrigation: It can significantly reduce the temperature and increase the humidity. After the sprinkler irrigation, the field temperature can be reduced by more than 2 degrees, the relative humidity is increased by 10-20%, and the effective time is about 2 hours. Sprinkling irrigation can reduce the empty rake rate by 2-6% and increase the grain weight by 0.8-1 gram. The time is appropriate from flowering to milking. (3) Spray chemicals: 0.1 kg of zinc sulfate per acre, or 0.1 kg of potassium dihydrogen phosphate is sprayed on the foliar; or 50 ppm of vitamin c or 3% of superphosphate solution is sprayed before the high temperature occurs. Has the effect of reducing heat and heat damage.
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