Technical Guidelines for Protecting Cotton Seedlings in Spring Planting

"Half the yield comes from good seedlings." Since late March, cotton sowing has been rolled out across the country. Because cotton prices opened high and kept rising last year, cotton production has shown a recovery trend this year, seed markets in various places started early, and seed@#@136@#@ has rebounded noticeably. In view of last year's abnormal climate, with rainy and low-temperature autumn weather, many rotten bolls and generally poor seed quality, plus the low temperature and drought of last winter and this spring, preparations must be made in advance and active responses taken to unfavorable weather of low temperature, drought or high humidity. According to forecasts from the Central Meteorological Observatory, there is a high probability of high temperature and drought this spring, so it is even more necessary to lay a good foundation, strive for full stands from a single sowing, and strong seedlings that develop early,

Direct seeding in the field: sow at the right time for a full stand from one sowing

1. Master the suitable sowing period. Cotton is a warm-loving, light-loving crop. Seed germination and emergence require the soil temperature at 5 cm to stably pass 14°C, and to rise to 16°C within a short period as the suitable temperature for sowing. In production, pay attention to weather forecasts and generally choose to sow at the end of a cold spell and the beginning of a warm one. In the inland areas, plastic film mulching and open-field sowing are generally done in mid-to-late April. In the northwest, the suitable sowing period is generally early to mid-April. On saline-alkali land in northern North China, soil temperature rises slowly, **and the northern slope of the Tianshan Mountains has heavy cold air, so sowing later within the suitable sowing period is advocated.

2. Build soil moisture and preserve it, and prepare the land finely. For direct seeding in the field, the Yellow River region and the northwest require sufficient subsoil moisture, so irrigate the root-zone subsoil moisture early, prepare the land finely, sow with sufficient soil moisture, and ensure good surface moisture. Generally, building soil moisture 20 days in advance is the best time. Considering the continuous drought and little rain since last winter and this spring, and tight water sources, soil moisture should be built in a timely manner according to local water source conditions, and after building moisture, harrow and level promptly to preserve it. Where there is no irrigation condition, it is recommended to cover with film early to raise moisture. About 30 days before sowing, after preparing the land while taking advantage of (or seizing) the moisture, cover with plastic film immediately and compact both sides of the film; when the temperature is suitable, punch holes in the film and do spot sowing. This method can reduce surface evaporation and maintain soil moisture, with notable effects on drought-prone and saline-alkali cotton fields, especially after a small amount of rainfall or after building moisture in advance and then covering with film at the right time; the effect is even better and it is worth promoting.

3. Plastic film mulching to increase soil temperature. Plastic film mulching can significantly increase soil temperature, cultivate strong seedlings, and promote early development. For direct seeding in the field, wide film mulching is advocated in the northwest. In North China, it is advocated to cover with plastic film first and then sow. Bury the film edges more than 5 cm deep and press them firmly; release seedlings in time to prevent high-temperature seedling scorching and film being lifted by strong winds. After sowing, check seedlings and reseed, and transplant to fill gaps. Generally, seedlings emerge completely 7-10 days after sowing; afterward, check seedlings plot by plot and bed by bed, and fill in with seeds and seedlings.

4. Do a good job in pest and disease control. Damping-off, seedling blight and anthracnose are the main diseases at the seedling stage. On the basis of seed coating, it is advocated to use half-strength Bordeaux mixture for control. Cutworms, snails, seedling aphids and cotton thrips are the main pests at the seedling stage; use trichlorfon to make poison bait or phoxim and other appropriate pesticides for control.

Raising seedlings in nutrient pots: cultivate strong seedlings

The area of seedling raising and transplanting accounts for around 45% of the national cotton field area all year round. It is distributed in the cotton areas of the Yangtze River basin and the Huang-Huai Plain and has a relatively good yield-increasing effect.

1. Choose a good bed site and fertilize the bed soil. The bed site is required to be high-lying, sheltered from wind and facing the sun, and the bed soil fertile and disease-free. Fertilize the bed soil, make beds to standard, 1.2 m wide and no more than 15 m long, dig surrounding ditches well, and ensure smooth drainage.

2. Use medium-sized pots in sufficient quantity. Prepare twice the number of pots needed according to transplanting density, water the pots sufficiently before sowing, sow 1 coated cotton seed per pot, cover with loose soil at a suitable thickness, and spray with carbendazim for disinfection to prevent seedling diseases.

3. Sow at the right time for a full stand from one sowing. Nutrient pot seedling raising requires the soil temperature to stably pass 10°C. Sowing time: for single-crop cotton fields, late March to early April; for cotton intercropped with wheat, early April; for cotton after rapeseed, sow in mid-April.

4. Strengthen management and cultivate strong seedlings. For sowing at low temperature, double-film mulching of the seedling bed is advocated. During this period, combine warming, cooling and good heat preservation; do not transplant seedlings, and do not remove the film from the bed. Move pots to harden seedlings, and remove the film before transplanting to acclimatize the seedlings.

5. Transplant at the right time and ensure density. Open furrows or punch holes for planting according to the planned density. When transplanting, ensure the pots are not broken, roots are not broken, the pot shoulders are not exposed, and the plants do not sink into pits. After planting, water thoroughly to settle the roots so as to shorten the post-transplanting recovery period.