Seed Selection Methods and Precautions for Sowing Winter Wheat

The wheat grown in our country is mainly winter wheat. Winter wheat is generally sown from mid-to-late September to early October and matures from late May to mid-to-late June of the following year. Because climate conditions and production conditions have changed abnormally in recent years, extra attention is needed during the wheat sowing process, so how should seed selection be done? What precautions need attention?

I. How to select winter wheat seed?

Choosing the variety is very important. Sowing spring-type and weak winter-type varieties on medium and early stubble fields will cause the wheat seedlings to grow excessively before winter, which is not conducive to safe overwintering. On the basis of early hoeing and pressing, the roots should be banked with soil before winter, or top-dressing with “mulch manure” should be applied, to protect the wheat seedlings for safe overwintering.

1. Cold resistance

Wheat varieties have three different types: spring type, semi-winter type and winter type. Wheat varieties must have a certain degree of cold resistance, but the requirement is not that the more cold-resistant the better; it is enough to ensure safe overwintering under local autumn sowing conditions. For planting winter wheat in the Kuitun reclamation area, varieties such as Xindong 22, Xindong 33 and Xindong 41 can be selected.

2. Disease resistance

The main threats to wheat production include: the three rusts, powdery mildew and take-all disease, etc. Therefore, when growers buy seeds, they should carefully understand the introduction of the variety's disease resistance.

3. Early maturity

Early maturity or an appropriate maturity period is an important condition for high and stable wheat yields. Early-maturing varieties can avoid or reduce certain natural disasters, for example: during grain filling and maturity they can escape dry hot winds and high-temperature diseases.

4. Lodging resistance

Only by selecting varieties with strong lodging resistance can yields be further increased and high and stable yields achieved. Generally, in field production, a plant height of 70--85 cm is relatively ideal. Xindong 22 has strong lodging resistance, while Xindong 41 is weaker; growers should choose according to their own soil fertility level and management level.

II. What precautions are there for sowing winter wheat?

1. Pay attention to tillage and land preparation

The purpose of tillage and land preparation is to make the wheat field achieve a deep plough layer, coordinated water, fertilizer, air and heat in the soil, moderately loose soil, strong water and fertilizer retention capacity, and good level ground, meeting the requirements for wheat sowing and creating conditions for full stands, strong seedlings and good plant growth.

In recent years, the area that is only rotary-tilled without deep ploughing is very large. In wheat fields that have been only rotary-tilled without ploughing for many consecutive years, a solid plough pan forms below the 15cm rotary tillage depth, affecting root penetration and water infiltration, resulting in less soil water storage and making wheat prone to premature senescence in the later stage. After 2 to 3 years of rotary tillage, ploughing should be carried out for 1 year to break the plough pan. In addition, the surface soil of rotary-tilled wheat fields is loose. If sowing is carried out without harrowing and smoothing first, the seed may be sown too deep, forming weak seedlings from deep sowing, affecting the occurrence of wheat tillering, causing insufficient spike number and reducing yield. Therefore, attention should be paid to harrowing and smoothing before sowing after rotary tillage.

In addition, pressing after sowing is also very important. Through investigation it has been found that under drought conditions, wheat fields pressed after sowing have stronger drought resistance, so pressing after sowing is advocated.

2. Sowing must not be too early or too late

(1) Sowing too early

If wheat is sown too early, after the seedlings emerge the leaves are narrow and long and drooping, with insufficient tillering, and the main stem and some large tillers enter the double-ridge stage of young spike differentiation before winter. When encountering a low temperature of -10℃ in winter, freezing damage will occur. Therefore, during sowing, timely pressing should be carried out to inhibit the growth of the main stem and large tillers; after pressing, hoe in time, and when necessary, spray the leaves with a 0.2%-0.3% chlormequat solution to control excessive growth and resist freezing damage.

(2) Sowing too late

Because the pre-winter growth period is short and accumulated temperature is insufficient, wheat seedlings grow thin and weak with few tillers. Therefore, wheat farmers should mainly hoe and supplement fertilizer and water, and topdress nitrogen fertilizer in time at the three-leaf stage; for wheat fields with poor soil moisture and rapid water infiltration, irrigate tillering water in time after the three-leaf stage. If soil moisture is suitable or the plot has heavy clay and poor water permeability, it should not be watered before winter.

3. Sowing must not be too deep or too shallow

(1) Sowing too shallow

The sowing depth of wheat is preferably 3-5 cm. If sown too shallow, wheat seedlings grow prostrate, the tillering nodes are exposed, and tillers are numerous but small, making them susceptible to freezing and premature senescence. It is recommended that wheat farmers press the field several times in time before wheat emergence, and after emergence combine hoeing with banking soil around the roots. When necessary, during the overwintering period, foreign soil covering or top-dressing with “mulch manure” can be used to prevent freezing damage during overwintering.

(2) Sowing too deep

If wheat is sown deeper than 5 cm, it is considered too deep. Sowing too deep will cause wheat to emerge slowly, with slender leaves, few and small tillers, few and weak secondary roots, and yellow, thin seedlings. The soil should be scraped away in time to clear the seedlings, using a bamboo rake or iron rake starting from the center of the plot, raking horizontally along the rows, and when clearing the last row, drag all the remaining soil onto the ridge back. A reminder to wheat farmers: for wheat sown at the appropriate time, pre-winter seedling clearing generally starts from the two-leaf stage and ends at “Minor Snow.”

4. Do not use herbicides when wheat seedlings are weak and roots are exposed

Generally, winter wheat fields undergo straw return, and the plot is relatively loose. If an abnormal weather year occurs, such as a warm winter and drought year, attention must be paid to the possibility that wheat roots cannot penetrate deeply because the soil is too loose, or that part of the root system is exposed. Such wheat is very prone to freezing injury and water shortage, and these wheat seedlings are the most sensitive and fragile. If herbicides are applied at this time, they are likely to cause certain harm to the wheat.