Why is it necessary to sun-dry wheat seeds before sowing?

Before planting winter wheat, taking preparatory measures such as selecting superior varieties, sunning the seeds, and applying seed coatings is the most critical task in the pre-sowing stage. Many farmers are unclear about why seeds should be sunned prior to sowing; let’s explore this issue further.

Why is it necessary to sun-dry wheat seeds before sowing?

Sun-drying wheat seeds before sowing helps prevent mold and insect infestation, promotes post‑harvest maturation, and enhances both germination vigor and germination rate, thereby fostering robust seedlings and boosting yields. Trials have shown that sun‑dried seeds exhibit a 14.6% to 17% higher germination rate than untreated seeds, with an average yield increase of 14.5% per mu.

Benefits of Sunning Wheat Seeds Before Planting

1. It can increase seed germination rate and enhance seed vigor.

After wheat becomes damp, the endosperm near the seed coat is hydrolyzed into a gelatinous substance, and the stomata on the seed coat become blocked, thereby hindering both water absorption and gas exchange. Seed germination requires adequate moisture and oxygen; when uptake of water and air is impeded, germination is inevitably compromised. Following sun‑drying, the seeds lose moisture and shrink, increasing the permeability of the seed coat. This facilitates the uptake of water and air after sowing, thereby enhancing both the germination rate and vigor of the seeds.

II. Promote post-harvest ripening of seeds.

Under high-temperature and dry conditions, sun-drying seeds promotes the synthesis of assimilates, completes physiological seed maturation, and facilitates the post‑ripening process.

3. It can kill pathogenic bacteria and pests.

By sunning the seeds, ultraviolet radiation in sunlight can kill pathogens adhering to the seed surface, thereby reducing wheat diseases such as smut, powdery mildew, and rust.

4. Sun-drying seeds helps prevent mold from further developing on damp seeds and allows for the prompt identification of severely moldy seeds, enabling timely replacement to ensure that planting schedules are not delayed.

The method for sun-drying wheat seeds is:

Choose a sunny, clear day and spread the wheat seeds evenly on a mat (be careful not to lay them directly on asphalt or concrete drying yards to avoid overheating and damaging the seeds), with a thickness of 10–15 centimeters. Turn the seeds frequently during the day, and pile them up and cover them at night; typically, drying in the sun for 2–3 days is sufficient.