How to control rice heat damage?

In China, rice heat damage mainly occurs in the flowering period of early and middle rice and the filling period of early rice. The heat damage during flowering mainly affects the opening, pollination and fertilization of spikelets, and the normal pollination is disturbed, and the pollen vitality is weakened, resulting in an increase in empty shell rate. The main symptoms of heat damage during grain filling stage are the increase of empty shell rate, the decrease of solid grain rate and 1000-grain weight. At the initial stage of grouting, the damaged shriveled grains (empty shells) increased and the solid grains decreased; The 1000-grain weight decreased in the later stage. High temperature and heat damage seriously affect rice yield and quality. In order to better control and prevent such diseases, the preventive measures of rice heat damage are summarized as follows.

1. Select high-temperature resistant varieties and arrange them reasonably.

Reasonable selection and application of high temperature resistant varieties in production. Early rice varieties with high temperature tolerance can also be reasonably matched with early maturity and high yield varieties, and varieties with high temperature tolerance can be selected to reduce the damage to grain filling and fruiting. Use early, middle and high yield varieties, avoid high temperature season, appropriately increase the number of basic seedlings, ensure enough panicles per unit area, and realize large-scale balanced yield increase. This measure should be applied flexibly according to the local climate characteristics.

2. Sow in time to avoid heading and flowering in high temperature weather.

According to the whole growth period of rice varieties and local climate characteristics, the sowing date should be adjusted to avoid heading and flowering in high temperature weather. Generally speaking, in the midsummer season from mid-July to early August, high temperature and heat damage are prone to occur. Therefore, the sowing date should be arranged according to the principle of heading date, avoiding the high temperature in midsummer, ensuring heading before the safe heading date and not affecting the subsequent crop planting.

3. Tian Tuan management

(1) Rational fertilization should be carried out earlier, depending on seedling conditions and proper fertilization. After booting stage, topdressing urea 15 ~ 20kg every 667m2. Spraying 0.2% ~ 0.3% potassium dihydrogen phosphate solution at the time of rice flowering and applying 50kg per 667m2 can effectively reduce the degree of heat damage.

(2) Reasonable shallow water irrigation, daily irrigation and night row, and timely drying at flowering stage to prevent premature water cut-off, so as to improve the microclimate of rice fields, promote strong roots and enhance high temperature resistance. Keeping the water layer 5 ~ 10 cm during the day can reduce the microclimate temperature in the field by 2 ~ 3℃. Daily irrigation and night drainage can increase the temperature difference between day and night, and the effect is better. Sprinkling irrigation before and after full flowering period can obviously reduce the temperature and increase the humidity. After sprinkler irrigation 1 time, the field temperature can be reduced by more than 2℃, the relative humidity can be increased by 10% ~ 20%, and the effective time is about 2 hours. Sprinkling irrigation can reduce the empty chaff rate by 2% ~ 6% and increase the 1000-grain weight by 0.8 ~1.0g. ..

(3) spraying chemicals: spraying water on the leaves with 0. 1kg zinc sulfate, 0.25kg salt or 0. 1kg potassium dihydrogen phosphate every 667m2; Or spraying 50mg/kg vitamin C or 3% calcium superphosphate solution before high temperature appears, all of which can reduce high temperature injury. Strengthen pest control, especially drug control of rice planthopper and rice leaf roller.

4. Store ratooning rice

After the occurrence of high temperature and heat damage, for the crops that have not been harvested, early-maturing varieties can be selected, and the empty ear can be cut off to store ratooning rice. The ratooning rice should be grown sooner rather than later, and measures such as fertilizer and water regulation can be taken to promote the early growth, early reproduction and early heading of ratooning rice to achieve ideal results.