High temperature heat damage can reduce corn production by 30% or even no harvest! How to prevent it, please see here!

This year there will be 40 days of summer, which is a serious challenge for corn growth, so what harm does high temperature heat damage do to corn? How to prevent these hazards?

High temperature and heat damage lead to maize yield reduction or failure

High temperature damage is a natural disaster encountered in maize production. After late July, summer maize in most areas is in the key period from vigorous vegetative growth to reproductive growth transformation, which is very sensitive to light, fertilizer, water, heat and gas. When the daily mean temperature of maize is above 35℃ and lasts for more than 5 days, and the ineffective rainfall lasts for more than 8 days, the high temperature heat damage will inevitably occur.

During this period, if suitable temperature, light and water conditions can occur synchronously with maize growth and development, it will be beneficial to growth and development and increase yield. On the contrary, if continuous high temperature and drought or rainy weather and other disastrous climatic conditions are encountered, growth and development will be seriously affected, resulting in reduced yield. Serious cases can reduce production by more than 30%, and more serious cases may lead to no production or harvest.

Grading of High Temperature and Heat Damage to Maize

The heat injury index of maize was 36℃ in seedling stage, 32℃ in reproductive stage and 28℃ in mature stage. Temperature higher than 32℃ during flowering is not conducive to pollination. According to the average temperature of the whole growth period, the light heat damage is 29℃, the yield is reduced by 11.9%, the moderate heat damage is 33℃, the yield is reduced by 52.9%, and the severe heat damage is 36℃, which will cause the yield failure. The maximum temperature of 38-39℃ causes high temperature damage, and the longer the time, the more serious the damage and the more difficult it is to recover.

Effect of high temperature on maize growth

1. Affect leaf photosynthesis

Under the condition of high temperature and drought, the chloroplast structure of leaves was destroyed, the leaves contracted, the photosynthetic area of leaves decreased, and the photosynthetic capacity of leaves decreased greatly.

2. Shorten the growth period

The high temperature forces various physiological and biochemical reactions in the growth process of maize to accelerate and shorten each growth stage. If the differentiation time of female ear is shortened, the ear becomes smaller, and the number of male ear floret differentiation decreases. High temperature at late growth stage makes maize plants die prematurely.

3. Affect female ear and male ear development

When the temperature was over 35℃, the number of male spike branches decreased, the floret degenerated, the anther thin and shriveled, and the pollen vitality decreased. When the temperature was over 38℃, the male spike could not bloom and the pollen shedding was blocked. High temperature caused abnormal differentiation of female panicle, delayed silking of female panicle, caused discordance between male and female, poor pollination and seed setting, thin and shriveled grain. In addition, high temperature is easy to cause diseases and reduce yield and quality.

Methods of Preventing High Temperature Heat Damage of Maize

In the prevention of corn high temperature damage methods, in addition to the selection of heat-resistant varieties, there are the following measures to choose from:

1. Artificial pollination to improve seed setting rate

During the period of high temperature and drought, the natural pollinating, pollination, fertilization and seed setting ability of maize decreased. If the weather of continuous high temperature above 38℃ was encountered during the flowering and pollinating period, artificial pollination was suggested to reduce the influence of high temperature on the pollination and fertilization process of maize and improve the seed setting rate. Fresh pollen is usually collected at 8-10 a.m., pollinated by self-made pollinators, and used as soon as it is collected. The yield increase effect of this method in rice cultivation field is very remarkable.

2. Reduce density appropriately and adopt wide and narrow row planting

Under the condition of low density, the contradiction between individuals competing for water and fertilizer is small, the individual development is strong, the ability to resist high temperature injury is strong, and the high temperature injury can be alleviated. Under the condition of high density, wide and narrow row planting is beneficial to improve the ventilation and light transmission conditions in the field, cultivate healthy plants and increase the resistance to high temperature injury.

3. scientific fertilization

In fertilizer management, increase the amount of organic fertilizer, focus on the application of basal fertilizer to promote early development, pay attention to the application of trace elements, promote early maturity of maize seedlings after emergence, and increase ear size from big bell stage to tasseling. In addition, combined with irrigation, the method of adjusting fertilizer with water is adopted to accelerate the fertilizer efficiency, improve the nutritional status of plants and enhance drought resistance. Foliar fertilizer can be sprayed during high temperature period, which is beneficial to cooling and humidifying, and can supplement water and nutrition necessary for corn growth and development.

4. irrigation at proper time

High temperature often occurs with drought. Spraying water ahead of time during high temperature can directly reduce field temperature. At the same time, maize plants get enough water after irrigation, transpiration is enhanced, canopy temperature is reduced, thus effectively reducing the degree of high temperature stress, but also partially reducing the respiratory consumption caused by high temperature, reducing high temperature damage. If conditions permit, sprinkler irrigation can be used to spray water directly on the leaves, and the cooling range can reach 1-3℃.