□ Wang Chengye Feng Xiaoxi
During the period from 2013 to 2017, in addition to 2015, the city's corn production was affected by high temperature and heat damage "four times in five years". In particular, last year's high temperature heat damage ranged the largest, affecting the province and the Huanghuaihai region, resulting in a decline in the vitality of summer corn pollen and filigree, pollen failure, and the ability of filigree to accept pollen became poor, resulting in poor pollination and poor fruiting, which brought great losses to summer corn production.
This year's volt period is as long as 40 days, and after the city enters the volt period, the high temperature above 35 ° C has become normalized. Judging from the medium- and long-term weather forecast, the high-temperature baking mode will continue. Due to the continuous rainfall during the wheat harvest, the summer corn sowing in our city this year is relatively concentrated, basically around June 1. From late July to early August, summer maize will be concentrated into the powdering period. If there is no effective precipitation for more than 8 days, or if the maximum temperature is greater than 35 °C for more than 5 days, summer maize will have drought and will suffer from high temperature and heat damage.
This year, the city's summer corn early rain is sufficient, and there is no seedling drought in previous years. On July 12, the city's general rain was moderate to heavy, and the soil moisture was relatively good, but the summer high temperature field evaporation was large, and the current good soil moisture could only be maintained for about a week. Summer corn in our city is entering the powder extraction period, and if there is no effective rainfall from July 20 to 30, high temperature and heat damage are very easy to occur. According to the forecast of the Central Meteorological Observatory, the next 20 days of the city will be affected by subtropical high pressure, will be mostly high temperature and little rain sweltering weather, the temperature will continue to be above 35 ° C, the maximum temperature will be between 38 ° C ~ 40 ° C, such weather will have an extremely adverse impact on the loose powder fertilization of summer corn, and the high temperature heat damage of corn will be formed with a high probability. Therefore, remind farmers and friends to be vigilant against the occurrence of high temperature and heat damage to corn.
To prevent the recurrence of high temperature heat damage, we must pay attention to the following points:
1. Understand the characteristics of male spikes of varieties and grasp the ability of varieties to resist high temperature and heat damage in time. Zhengdan 958 white shaft varieties have strong adaptability to the climate of the Huang-Huai-Hai region, the male spikes are relatively developed, the amount of pollen is large, the powder cycle is long, and there is a strong adaptability and resistance to high temperature and continuous rainy weather. The 335 types of red shaft varieties of American xianyu generally have few branches and short ears, the shell is not full, the amount of pollen is small, the powder cycle is short, the resistance to high temperature heat damage is poor, and it is susceptible to high temperature heat damage. For such varieties, farmers and friends should pay special attention.
2. Predict the bulk period. Go to the field in time to observe whether the maize powder period is in the high temperature and drought period from July 20 to 30. If it is a variety that is susceptible to high temperature heat damage, and the powder release period is during the high temperature and drought period, effective prevention and control measures must be taken.
3. Be prepared and watered in time. Plots with irrigation conditions should be quickly inspected and prepared for irrigation facilities, and the weather forecast should be constantly monitored. If the forecast is from July 20 to 30, there is no moderate to heavy rain or continuous light rain, and the corn is in the flowering and powdering stage, it is necessary to take advantage of the cooler time of the day to water as soon as possible to reduce the temperature of the field, maintain the water of the plant at a reasonable level, which is conducive to pollination, and pay attention to prevent heat stroke. If there is no irrigation condition, artificial auxiliary pollination can be carried out in the cooler morning, that is, artificial shaking of the plant, so that the pollen falls on the filament as soon as possible, pollination before the pollen inactivation, to ensure that the ear of the fruit is fertilized and expanded. (The authors are the director of Zhumadian Comprehensive Experimental Station of Henan Corn Industry Technology System and the associate researcher of Maize Research Institute of Municipal Academy of Agricultural Sciences)