Detailed Explanation of Key Techniques for Achieving a Full Stand of Cotton from a Single Sowing

The technique of achieving a full stand of cotton from a single sowing has been a technical issue of concern to our cotton farmers and technicians for many years. It involves many factors - soil temperature, soil moisture, sowing methods, seed quality and treatment - all of which are key to achieving a full stand from a single sowing. Therefore, we discuss with cotton farmers how to achieve a full stand of cotton from a single sowing with strong seedlings and early development.

I. Pre-sowing preparation. Preparation before sowing is the prerequisite and foundation for a full stand from a single sowing. As the saying goes, "Troops and horses move only after provisions are ready" and "Ten months of pregnancy, one day of delivery" - both illustrate the importance of preparation.

Pre-sowing moisture building: Due to years of drought, the groundwater level has been declining sharply. Surface moisture formed by rainfall can no longer solve the drought situation, and can only play a role in alleviating it. Last year, sudden rainstorms during the sowing period were very favorable for sowing by capturing moisture, but during the period before the first fu day, the cotton fields encountered drought. All cotton fields that had not built moisture before sowing showed severe drought symptoms, and those that were not watered in time had reduced yields. This shows that pre-sowing moisture building in cotton fields is extremely important.

For moisture building in cotton fields, the best method is to plow dry first and then irrigate. That is, 15 days before sowing, before irrigation, apply sufficient base fertilizer, plow the land, and then water to build moisture. To save water, after dry plowing, harrow level 1-2 times, divide into small plots and irrigate. This can speed up the irrigation progress and achieve the effect of rapid moisture display and rapid temperature rise. Do not plow again. After 2-3 days, harrow the land level and compact it, then it is ready for sowing. The advantage of this method is that moisture will not be lost due to building moisture too early. It will not fail to achieve the loose top and firm bottom of the cotton field due to lack of harrowing. It is superior to fields that are irrigated first and then plowed, and to fields sown by capturing moisture, in terms of moisture conservation and controlling sowing depth. It is worth promoting.

Seed preparation: At present, the phenomenon of "many, chaotic, and mixed" cotton varieties in the market is quite serious. Companies are numerous, varieties are numerous, genuine and fake are mixed, and fakes pass as genuine. This brings difficulties to our cotton farmers in selecting superior seeds. Therefore, it is suggested that cotton farmers should buy cotton seeds from seed companies with all three certificates. What does "all three certificates" mean? That is, seed quality certificate, seed quarantine certificate, and seed distribution license. For the selected superior seeds, first, the comprehensive traits of the variety should be good, with high yield, good quality, strong disease resistance, and the right variety for the local conditions. Second, the seed purity should be high, quality good, and the healthy seed rate and germination rate relatively high. As for current varieties, conventional insect-resistant cotton seeds include Ji 668 and CCRI 45 (formerly Zhong 221), and hybrid cotton includes Lumianyan 15. Demonstrate and plant the new line Wang A03, a disease-resistant line that is free from pruning, to realize the wish of "easy cotton planting, still high yield." The insect resistance of the above varieties (lines) is comparable to that of American cotton, but their yield performance and disease resistance are superior to American cotton, so they can be used with confidence in production.

Due to last year's climate conditions, this year's healthy seed rate will generally decline, and maturity will be insufficient. Therefore, for field planting this year, it is best to choose delinted and coated seeds that have been processed and carefully selected. Coated seeds must strictly not be soaked. For uncoated cotton seeds, combine soaking with selection to eliminate seeds with yellow or red seed coats, so as to increase the germination rate. For fuzzy seeds, chemical seed dressing is advocated. The treatment method is to dress 10 kg of cotton seeds with 50 g of triadimefon (Triadimefon). This can effectively prevent seedling-stage diseases. Whether coated seeds or fuzzy seeds, 15 days before sowing, choose sunny days and sun the seeds for 2-3 days to break seed dormancy and increase the germination rate.

II. Sowing and sowing methods: The early or late sowing period has a significant impact on cotton emergence, yield, and quality. Therefore, sowing at the right time is very critical. Temperature is an important basis for determining the sowing period. Generally, when the 5 cm soil temperature stably passes 14-15°C, it is the suitable sowing period. Varieties with a long growth period can be sown early at the appropriate time, and short-season varieties can be sown late at the appropriate time. For saline-alkali land where moisture building is close to the sowing period, sowing should be appropriately delayed by 5-10 days.

Accurately grasping sowing depth is the prerequisite for uniform and strong seedlings. Because in most cotton fields, moisture building and sowing are very close in time, soil water content is high, and soil temperature is relatively low. If sowing is too deep, not only will emergence be poor, but it will also cause seedling-stage diseases, root rot, and dead seedlings. The required sowing depth for delinted coated seeds is 1.5-2 cm, and for fuzzy seeds 2-3 cm.

The sowing rate should be determined by the sowing method (hill dropping, drilling, etc.), germination rate, retained plant density (row spacing arrangement), and soil conditions. For hill dropping, each hole should not have fewer than 3 seeds. For drilling, use about 2 kg of high-quality delinted coated seeds per mu, and about 3 kg of fuzzy seeds. For plots with poor soil moisture, clayey soil or saline-alkali land, and severe underground pests, the sowing rate should be increased as appropriate.

For cotton fields lacking water sources and without conditions for moisture building, methods such as deep sowing with shallow covering, sowing by utilizing existing moisture, and water-seeded packets can be used.

III. Checking seedlings, replanting, thinning, and final thinning: After cotton seedlings emerge in rows, if missing seedlings or broken rows are found, timely germination and replanting or sprout seedling transplanting should be carried out. Sprout seedling transplanting adopts taking seedlings on site, taking from dense areas to fill sparse areas. It is simple and easy, with a high survival rate. If transplanting after the two cotyledons are flat and open, soil-ball transplanting can be adopted. When transplanting, the soil ball should be large and must not break apart, and a small amount of water should be applied appropriately.

Thinning is required after the seedlings are uniform, thinning to the extent that leaves do not touch each other. Final thinning should be done at the 1-2 true leaf stage. In years when spring temperature rises slowly, large numbers of dead seedlings are often caused by seedling diseases, resulting in severe missing seedlings and broken rows in cotton fields. Therefore, cotton farmers strongly delay the final thinning time, causing seedling diseases to worsen, making it impossible to ensure planting density, and at the same time easily forming tall, spindly, weak seedlings and causing delayed development and late maturity of cotton. Under these circumstances, the final thinning time must not be later than the three true leaf stage. At this stage, the cotton roots have become lignified, and the ability to resist adverse environments is greatly enhanced, so dead seedlings due to seedling diseases rarely occur.