Latest Factors Affecting Corn Harvests and Countermeasures

The phenomena of corn failing to set ears, or producing ears that do not fill out with plump kernels, are widespread in corn production fields in our region, thereby limiting increases in corn yield.

Influencing factors

1. Variety selection

Severe mixing and degeneration of inbred lines, poor quality and low purity of parent seed, and poor individual development reduce the yield-increasing effect of the hybrid; intrinsic seed factors such as degeneration of physiological function, metabolic disorders, and obstruction of the internal transport system cause earlessness and affect yield.

2. Soil fertility

Fields with poor fertility, low organic matter content, an imbalanced ratio of nitrogen, phosphorus and potassium fertilizers, deficiency of boron and zinc fertilizers, and insufficient topdressing cause slow ear development, prevent normal pollination, and increase the rate of barren stalks.

3. Planting density

Excessive planting density causes plants to shade one another, which leads to poor development of the female ear silks and poor pollination, resulting in reduced yield.

4. Damage from pests and diseases

Corn has many pests and diseases, especially northern leaf blight (southern leaf blight), smut, the Asian corn borer, and leafhoppers, which destroy the tissues of the female ear, consume nutrients in the plant, affect ear development, and lower yield.

5. Climatic factors

Excessive rain, poor ventilation and light penetration, dry hot winds, or low-temperature cold damage in the middle period delay tasseling, affect or inhibit young ear differentiation, and cause reduced yield.

Countermeasures

1. Variety selection

Choose varieties with good yielding ability, high yield potential, excellent quality, strong stress resistance, wide adaptability, and a compact plant type. In the northern Xinjiang region, the main varieties grown are Xinyu No. 18, Denghai No. 9, SC-704, and Nongda 108.

2. Seed treatment

Before sowing, carry out seed coating and sun-drying of seed, and dress seed with carbendazim powder at 1:1000 to control pests and diseases.

3. Sowing time

The sowing date in each area must be determined according to the local climate records over the years and the patterns of meteorological disasters, arranging the corn tasseling and pollination period before the summer drought. For corn with plastic film mulching and for seedling transplanting, the sowing date is 10-15 days earlier than conventional planting, and it is best that the transplanting period and the emergence period of film-mulched corn avoid the local frost period. Within the suitable sowing period, sow early while there is sufficient soil moisture, making full use of the favorable climatic conditions of late spring and early summer to avoid the summer drought. In our region, temperatures are low in the early stage and aboveground growth is slow, which makes it easy to control seedling growth and promote vigorousness, enhancing drought resistance. Timely early sowing can also lengthen the growth period and increase the accumulation of nutrients, creating conditions for large ears, more kernels, plump kernels, and increased kernel weight.

4. Fertilizer and water management

Fertilize according to a formula, apply potassium fertilizer skillfully, and supplement boron, zinc and other micronutrient fertilizers. For topdressing, apply seedling fertilizer lightly, jointing fertilizer skillfully, ear-setting fertilizer heavily, and grain fertilizer as appropriate. When phosphorus and potassium fertilizers in the base fertilizer are insufficient, appropriately increase them at the jointing or large trumpet stage. At the corn jointing stage, apply 10 kg of urea per 667 sq m, and keep the field water-holding capacity at 65%-70%. At the large trumpet stage, apply 10-15 kg of urea per 667 sq m, and keep the field water-holding capacity at 70%-80%; if the soil water-holding capacity is below this level, irrigate promptly. During the flowering, pollination and grain-filling stage, apply 5 kg of urea per 667 sq m. During the corn growth period, spray plant growth regulators on the leaves to extend the functional period of the leaves, promote roots and strengthen stalks, and meet the nutrient demands of ear differentiation.

5. Planting density

Determine the corn planting density according to factors such as soil fertility, fertilization level, variety characteristics, and cultivation level. For example, for mid-late maturing varieties with a longer growth period and large ears, keeping 3800-4000 plants per 667 sq m is appropriate; for mid-early maturing varieties with a shorter growth period and small ears, keeping 4200-4500 plants per 667 sq m is appropriate. When determining density, for the same variety, not only the plant architecture must be fully considered, but also the sowing date and the fertility level of the planting plot; fertile fields should be sparser and lean fields denser, adjusting to local conditions and handling it flexibly.

6. Field management measures

When corn seedlings grow to 3 leaves, thin the seedlings, removing crowded seedlings, weak small seedlings, and diseased or damaged seedlings. When corn seedlings grow to 5 leaves, finalize the seedlings according to the planned retained plant density, removing the weak and keeping the strong, removing the small and keeping the large, striving for uniform and complete seedlings and strong seedlings. Do a good job of intertillage and weeding, and carry out pest and disease monitoring. Give priority to spot and localized control, prohibit blanket chemical control, and when insect pests occur, use the methods of dropping into the whorl and spraying, which give obvious control effects. For each 667 sq m, use 1.5-2 kg of carbofuran granules plus 15-20 kg of sand or fine cinder, mix evenly, and then broadcast it into the corn leaf whorl.

Before flowering, detassel every other row; for husks that are too long, cut off 3-7 cm from the top. At the same time, on sunny mornings after the dew has dried, pollinate by the rope-pulling method or the plant-shaking method, once every 2-3 days for 2-3 consecutive times, which can increase pollination opportunities and promote full ears. In the middle and late stages of corn silking, for individual plants that have not yet set ears, gently bend the stalk between the first and second leaves above without breaking it, to increase the chance of pollination.