Five key measures for cotton seedling stage management

Cotton takes about one month from emergence to squaring, which is a single vegetative growth stage and an important growth period for promoting deep root penetration, preventing seedling diseases, promoting early development, and thereby achieving early squaring. Field management of plastic-film cotton mainly includes: timely releasing seedlings, intertillage and loosening soil, checking and replanting seedlings, disease and pest control, thinning and final thinning, etc. Cotton farmers everywhere have a lot of experience in cotton seedling stage management, which is worth promoting, and is summarized as follows:

Release seedlings early, seal holes late. When 50% of cotton seedlings have emerged and the cotyledons have flattened and turned green, the seedlings can be released in batches. The principle for releasing seedlings is: release in the morning and evening on sunny days, and release throughout the whole day on cloudy days. Some cotton farmers dare not release seedlings early and release them too late, so the cotton seedlings stay under the film for too long, which easily forms leggy seedlings and diseased seedlings, and they may even die from sunscald when exposed to high temperatures at noon. This practice is not advisable. Sealing the seedling release holes late is mainly aimed at preventing seedling diseases. Although Qixing Duokang cotton has disease resistance, it is also susceptible to disease under prolonged low-temperature, rainy, and cold conditions. Therefore, when soil moisture is high, sealing the seedling release holes late for ventilation and drying is a powerful measure for preventing cotton seedling diseases.

Transplanting to fill gaps: Full stands are the foundation of a bumper harvest. We should seize the good opportunity of rainfall after emergence and promptly check and replant seedlings. For plastic-film cotton with 20% to 30% missing plants, large seedlings with soil can be transplanted. Select healthy cotton seedlings of uniform size with 1 to 2 true leaves and transplant them with a seedling transplanter. The 13 cm seedling transplanter should be pushed all the way down to ensure the depth of the soil block, so the survival rate of transplanted cotton seedlings can reach 100%.

Thinning and final thinning. Immediately after a basically full stand is achieved, thin the seedlings. For hole sowing, 2 healthy seedlings can be retained; for drill sowing, thinning should be done so that leaves do not touch leaves. Where the sowing rate is small, thinning and final thinning can be completed in one operation. If seedling disease is severe, or in saline-alkali cotton fields, the time for final thinning should be appropriately delayed, and final thinning at 3 to 4 true leaves is suitable. For Qixing Duokang cotton, thinning at one true leaf and final thinning at 3 true leaves are suitable.

Intertillage and earthing up: After cotton emerges, intertillage and earthing up should be carried out in a timely manner, achieving early intertillage, frequent intertillage, and deep intertillage, shallow first and then deep. In rainy and low-temperature conditions, it should be deepened. Before 3 true leaves, the intertillage depth should gradually increase from 3 to 4 cm to 6 to 9 cm. After 4 true leaves until squaring and flowering, deepen it to 12 to 15 cm.

Topdressing at seedling stage. We generally do not advocate topdressing at the seedling stage, because the base fertilizer has already been applied sufficiently. If base fertilizer was not applied, topdressing at this time needs to be deeply applied 9 to 10 cm at a distance of 10 cm between plants, and deeply buried after application. When preparing the land before sowing, sufficient base fertilizer must be applied to achieve balanced fertilization, increase the application of organic fertilizer and potassium fertilizer, adjust nitrogen fertilizer, apply phosphate fertilizer steadily, and supplement trace fertilizers. Before and after final thinning, spraying a 600-fold dilution of Shengtaiyuan foliar fertilizer once combined with pest control has a very good effect.