Is rice resistant to high temperature? How to deal with the heat damage caused by high temperature? What's the impact?

The damage of high temperature to rice plant is closely related to the growth period of rice. Many studies have shown that in the flowering stage, high temperature heat injury will affect pollen maturation, anther cracking, pollen germination in stigma and elongation of pollen tube, resulting in the most serious damage to rice by non-fertilization, which is the sensitive period of rice to high temperature. especially when there is high temperature stress on the flowering day, it is easy to induce floret sterility, cause fertilization obstacle, and seriously affect seed setting rate and yield. Due to the intensification of industrialization, the increase of human activities and the influence of Greenhouse Effect, the climate has a gradual warming trend, and the frequency of high temperature heat damage is increasing, which should be paid attention to in production.

1. Pathogeny

Rice is extremely sensitive to temperature at budding and heading stage (10 days before and after heading). The most suitable temperature is 25 ℃ ~ 30 ℃, and the daily average temperature above 30 ℃ will have an adverse effect. If there is a continuous high temperature of more than 35 ℃ at the booting stage, the floral organ development is not complete, the pollen development is poor, and the vitality is decreased; if the high temperature is more than 35 ℃ at the heading and flowering stage, heat damage will occur, which will affect the loose powder and pollen tube elongation, resulting in the formation of empty shell grains, resulting in the decrease of seed setting rate, low 1000-grain weight and even no harvest.

two。 Influence characteristics

⑴ has a large disaster area.

In 2003, out of more than 500,000 mu of rice in Lai'an County, Anhui Province, more than 400,000 mu of rice were affected, and the area of no harvest reached more than 50,000 mu, resulting in a direct economic loss of 100 million yuan. In 2006, the heat-damaged area of Chuzhou, Hefei, Lu'an and Chaohu alone reached about 2 million mu, of which 500000 mu were seriously affected.

There are differences among ⑵ varieties and combinations.

Because the genetic characteristics of different rice varieties determine their tolerance to temperature is different, so the harm degree of high temperature heat damage to each variety is different.

In general, the high temperature heat damage of japonica rice or parent combinations containing japonica rice genes is more serious than that of indica rice.

The high temperature heat damage of hybrid rice is more serious than that of conventional rice.

The varieties without heat-resistant genes were more harmful than those with heat-resistant genes.

3. Prevention method

⑴ chooses varieties resistant to high temperature.

There are some differences in the damage degree of different varieties to high temperature heat damage. Farmers should first choose high-yield and high-temperature-tolerant varieties in production to reduce the effect of high temperature on grain filling and fruiting. For example, high temperature tolerant varieties Hongliangyou 166 and Hongliangyou 5 were widely planted in Anhui, Hubei, Jiangxi and other provinces from 2003 to 2006, showing the characteristics of high temperature resistance, strong drought resistance, high yield and good comprehensive condition, and were welcomed by farmers.

⑵ sowing and transplanting in time

According to the situation of high temperature in previous years, sowing and transplanting should be timely, so that the best heading and flowering date of mid-season rice should be arranged in the middle of August, so as to effectively avoid the frequent high temperature and summer drought weather from late July to early August.

⑶ adopts deep water irrigation and uses water to regulate temperature.

Keeping a certain water layer in the paddy field can significantly reduce the degree of yield loss in the climate of high temperature and drought. When the field water layer is kept at 5-10 cm during heading and flowering stage, the field microclimate temperature can be reduced by 2-3 ℃, and the heat damage can be reduced. Especially for the fields that are short of water and dry, it is necessary to raise water for irrigation as early as possible to increase field humidity and prevent the superimposed effects of drought and high temperature heat damage. Where there are conditions, daily irrigation and night drainage or long running water irrigation can be adopted.

⑷ adopts spraying fertilizer outside the root to enhance the stress resistance of rice.

3% superphosphate solution or 0.2% potassium dihydrogen phosphate solution was sprayed outside the root, plus foliar nutrient liquid fertilizer was sprayed to enhance the resistance of rice plants to high temperature and improve seed setting rate and 1000-grain weight.

⑸ topdressing Grain Fertilizer to prevent and treat late premature senility

For the fields with less heat damage at booting stage, the grain fertilizer was applied once before and after the break stage, generally applying urea 3kg / mu to restore the normal filling and fruiting of the plant.

⑹ can prevent and control diseases and insect pests and promote healthy growth of plants.

To achieve the combination of disease and insect prevention and heat damage prevention. Rice mainly controls diseases and insect pests such as rice planthopper, rice leaf roller, rice blast, sheath blight and so on. Foliar spraying fertilizer must have a good grasp of spraying concentration and time. The solution concentration should not be too high, otherwise, too high concentration can easily lead to plant leaf damage and affect nutrient absorption; the best time is in the evening.

4. Remedial measures

⑴ stores ratooning rice. The fields that suffered from high temperature from late July to early August, with a seed setting rate of less than 20%, a yield of less than 100 kg per mu, and a good water source, should be cut for stubble and ratooning rice before August 15. When cutting seedlings, it is necessary to keep low stubble in early cutting and high stubble in late cutting, and the earlier the better, the better. At the same time, the management of regenerated rice fields should be strengthened to ensure safe full heading and higher yield.

⑵ was converted to autumn crops. For fields with a seed setting rate of less than 20% and poor water source conditions, the storage of recycled rice may fail due to high temperature and drought. We should choose the cultivated land of cutting seedlings and plant autumn crops in time, such as vegetables, red mung beans, autumn buckwheat, fresh sweet corn and other grain crops with short growth period, so as to make up for the loss caused by high temperature damage.