The defense technology of wheat late frost

Wheat frost falls below 0°C in the ground and falls below the minimum temperature that wheat can withstand in a certain developmental stage, causing wheat to suffer freezing injury. After the jointing of wheat, the cold-resistance ability gradually weakens, and it is vulnerable to frost damage. From the external shape of the plants, some of the wheat damaged by frost may be damaged by the stem, some may turn yellow and twisted, and the plants may wither. They may also cause the male and female of the panicle. The core is frozen and the floret is degraded. The seed setting rate is reduced and the yield is affected. Therefore, to strengthen forecasting and defense, common defense methods are as follows: First, the effect of irrigation and water frost protection: First, the water temperature of irrigation, higher than the soil temperature during frost occurrence, and sometimes higher than 10 °C, so the irrigation energy before frost Bring a lot of heat; Secondly, after irrigation, the moisture content of soil moisture enhances the thermal conductivity of the soil. Third, because water has a much larger potential capacity than air and soil, it can reduce ground temperature after irrigation. In order to avoid hot and cold; Fourth, after the water, the air in the near-surface air increased, in the occurrence of condensation can be latent heat. In areas with sprinkling conditions, spraying water in the event of frost and adjusting the microclimate in the field are very effective in preventing frost. According to the investigation, before the occurrence of frost, the ground temperature can be increased by 1 to 3°C, the maximum value is 4.1°C, and the temperature of the foliage is increased by 0.2 to 0.7°C. The frost damage is significantly reduced. Second, smog smoke around the application of firewood smoke anti-frost has a long history. In areas with insufficient fuel, CHN chemical smokers can be used. The agent is a mixture of ammonium nitrate, residual oil and sawdust. The main effects of frost prevention are: first, the formation of a smoke screen during combustion, and the attraction of radiant heat inside the smoke, which can reduce the radiation cooling on the ground and prevent the soil and plants from losing heat; second, the smoke can burn and release heat to make the temperature Thirdly, when the water vapor condenses on the smoke, it releases latent heat and it also raises the temperature. The time for smoking must be mastered. It should not be too early or too late. Generally, when the temperature of the leaf surface drops to 1°C higher than the frost index, it is necessary to publish the cigarette lightening time and ensure the quality, so as to obtain good results. Third, the use of frost-resistant varieties of frost-prone areas, generally frost damage. Therefore, it is necessary to select and match the cold-tolerant varieties that are planted late in the festival. Because the early jointing varieties are susceptible to freezing damage, the late jointing varieties come in the form of late frosts and show strong cold resistance and light freezing injury. Fourth, strengthen the cultivation and management to improve the antifreeze ability of wheat (1) timely sowing early sowing start jointing early, vulnerable to freezing injury. (2) Implementation of repression before jointing can inhibit the growth of roots, promote root development, and reduce the effects of frost. (3) Based on the situation of the seedlings, based on antifreeze and reasonable fertilization. Excessive application of nitrogen fertilizer plants prosperous, susceptible to frost damage, and more phosphorus and potassium fertilizers, can increase frost resistance, have a significant effect on defense frost. (4) Foliage sprayed with chlormequat and paclobutrazol at the jointing stage can inhibit plant growth and reduce plant height, and it can both prevent and freeze.