Disasters Related to the Lesser Fullness of Grain
After the Lesser Fullness of Grain, temperatures above 35°C begin to appear in the area south of the Yellow River to the middle and lower reaches of the Yangtze River. Relevant departments and units should pay attention to heatstroke prevention.
In terms of climate, during the Lesser Fullness of Grain, most parts of China have successively entered summer. The temperature difference between the north and south further narrows, precipitation increases, and plants in nature become full and lush. The grains of wheat gradually become plump, summer-harvested crops are nearing maturity, and spring-sown crops are growing vigorously, entering the busy period of "Three Summers": summer harvest, summer planting, and summer management. During this period, wheat-growing areas across the country should intensify the prevention and control of pests and diseases in wheat fields. For the North China region, there is a saying, "If the Lesser Fullness of Grain is not full, the wheat faces a risk," which means that when winter wheat in North China reaches the Lesser Fullness of Grain stage, it enters the maturity phase and is most vulnerable to attacks of dry-hot wind. At this time, the rainy season in North China has not arrived, and it is a period of drought. Due to strong solar radiation, the ground temperature rises quickly. When a dry-hot weather forms with a temperature as high as 30°C, a minimum relative humidity of less than or equal to 30%, and wind speeds of 3-4 meters per second or higher, the wind that blows is a dry-hot wind. Dry-hot wind is extremely harmful to wheat from the flowering to the milk-ripe stage. It accelerates the crop's evaporation rate, causing water in the plant to evaporate quickly, destroys chlorophyll, stops photosynthesis, and causes stems and leaves to wither quickly. As a result, the grains become shriveled, have thick husks and deep grooves, and the thousand-grain weight decreases, generally reducing the yield by 5-10%, and in severe cases, by more than 30%.
To prevent dry-hot wind, early-maturing varieties should be used as much as possible. When encountering dry-hot wind, it is necessary to water the crops quickly and spray a solution of plant ash. The ratio is 1 jin of plant ash to 5 jin of water, with 40-50 jin sprayed per mu. Another method is to spray a growth promoter: 1 liang of promoter mixed with 100 jin of water. Spraying this can increase the water content in the leaves, enhance water retention, strengthen photosynthesis, and reduce respiration intensity, which helps defend against dry-hot wind. Additionally, applying nitrogen fertilizer in advance, controlling the use of nitrogen fertilizer during the grain-filling stage, and increasing phosphorus in the base fertilizer are all beneficial for wheat grain-filling and have a certain effect in preventing dry-hot wind. Furthermore, the period of frequent thunderstorms and strong winds has now arrived. All regions should pay close attention to weather forecasts and try to avoid losses caused by these disastrous weather conditions.