Detailed Explanation of Key Cultivation Techniques for Single-Stem Wheat After Cotton Stubble

With the adjustment of the planting industry structure, the area of wheat-cotton double cropping has developed rapidly across various regions, achieving both expansion and increase in grain and cotton production. However, some problems have also been exposed, namely that the suitable sowing period for @#@245@#@ coincides with the cotton harvesting period. Using conventional sowing methods has brought many adverse effects on wheat growth and development, such as small seedlings, weak seedlings, susceptibility to freezing, poor root development, fewer productive ears, and low and unstable yields. If timely stubble clearing is adopted and the single-stem wheat cultivation method is applied around Frost's Descent, this contradiction can be well resolved. The main cultivation techniques are as follows:

1. Timely pulling of cotton stalks and timely stubble clearing. Cotton is a thermophilic crop; when the temperature drops below 15°C, cotton bolls no longer gain weight, while wheat is relatively cold-tolerant, and around 15°C is suitable for wheat germination, seedling emergence, and seedling-stage growth. Therefore, when the temperature drops to around 15°C on October 15-20, pulling out the cotton stalks and timely clearing stubble for wheat will not cause cotton yield reduction. For late-developing cotton fields, ethephon can be sprayed at an appropriate time and rate for ripening promotion, preferably in early October, generally using 100-150 ml of 40% ethephon per mu, mixed with 40-50 kg of clean water, evenly sprayed on cotton bolls that are 35 days or older. At the same time, to shorten the sowing time, the "five rush" tasks must be carried out, namely rushing to pull stalks, rushing to apply fertilizer, rushing to plow, rushing to prepare seedbeds, and rushing to sow. Before pulling stalks, soil fertilizer should be transported to the field edge, and the bottom moisture water should be watered sufficiently and well. Then, as stalks are pulled, fertilizer is applied, and plowing and seedbed preparation follow. It is essential to change from interplanting with cotton stubble to pulling stalks, plowing, and sowing wheat, in order to loosen the soil and prevent wheat rosette dwarf virus disease.

2. Rational arrangement of intercropping patterns. The general principles for rationally arranging intercropping patterns are: grow wheat well, take good care of cotton, manage this year well, and plan well for next year, with the goal of improving economic benefits and achieving high yields of both grain and cotton. In flat irrigated fields with good conditions and fertile soil, the "four-two" pattern can be used; units with poor irrigation conditions but with certain management skills can use the "three-two" pattern; intercropping summer cotton with nutritional pots in wheat fields is called the meter three-one pattern. The four-two pattern has a belt width of 1.6 m, formed into high and low beds; four rows of wheat are sown in the 0.5-0.6 m low bed, and the high bed ridge is 1-1.1 m wide, intercropped with two rows of cotton. The three-two pattern has each belt of 1.5 m; three rows of wheat are sown in the 0.5 m low bed, and the high bed is 1.0 m wide, planted with two rows of cotton. The three-one pattern has a belt width of 1 m for three rows of wheat, with a bed ridge width of 0.6 m, intercropped with one row of cotton or wheat, and one intercropping row is left for every three rows to intercrop summer cotton.

3. Implementing single-stem cultivation. Single-stem wheat cultivation is a high-yield late-season flat cultivation method mainly based on main-stem ears. It is a new approach for achieving high yields in wheat after cotton stubble, with outstanding characteristics such as late sowing without late maturity, high density, and no lodging. It usually increases yield by 15-20% compared with conventional wheat after cotton stubble. The highest yield can reach over 600 kg per mu. Its key technical points are:

1. Select varieties with late sowing, early maturity, and compact plant type. Based on experiments and production practice in recent years, wheat varieties suitable for single-stem cultivation in western Liaoning and southwestern Liaoning include Liaomai No. 1, Liaomai No. 15, Liaomai No. 16, Shaan 7859, and Jimai 5418, etc.

2. Apply more phosphorus and less nitrogen in base fertilizer. Because the previous crop of cotton stubble wheat consumes a large amount of soil nutrients, sufficient base fertilizer must be applied before plowing. Generally, apply 3000-4000 kg of high-quality farmyard manure per mu, 50-75 kg of superphosphate, 10-15 kg of potassium chloride, and 2.5 kg of seed fertilizer (urea). For high-fertility plots, nitrogen fertilizer may not be applied in the base fertilizer; for lower-fertility plots, nitrogen fertilizer may be applied as appropriate, but not exceeding 1/3 of the total nitrogen fertilizer amount used during the entire growth period.

3. Sow at the appropriate time with sufficient soil moisture. Sowing with sufficient soil moisture is a key link for full stand, uniform stand, and strong seedlings of wheat, and is especially important for ensuring a full stand of wheat after cotton stubble and safe overwintering of wheat seedlings. This is because under conditions of late sowing and low temperature, the seed germination rate is low and seedling emergence is slow. If there are missing seedlings or broken rows, replanting is difficult. Only by sowing with sufficient soil moisture can one gain the initiative for stable and high yields with sufficient plants and ears. Methods such as sowing with stubble at suitable moisture before sowing or shallow sowing followed immediately by watering "covering-head water" can be adopted to solve this. Different cultivation methods have different suitable sowing periods. The best sowing period for single-stem wheat is when the daily average temperature is 12-16°C (pre-winter accumulated temperature 250-550°C). In southern Liaoning, it is generally around Frost's Descent.

4. Increase basic seedlings and reduce row spacing. Increasing basic seedlings is one of the most important technical links in single-stem cultivation of wheat after cotton stubble. It is required to reach or approach the suitable number of ears per mu for conventional high-yield cultivation of the variety, so as to ensure ears through seedlings. Generally, for multi-ear varieties, the basic seedlings are 550,000-600,000; for medium-ear varieties, 400,000-450,000; for large-ear varieties, 350,000-450,000. Because the density of single-stem cultivation is relatively high, plants tend to be too crowded in the early stage, and in the later stage the wheat plant type is relatively compact, making it easy for light to leak between rows. To coordinate the contradiction between early and late stages, row spacing should be reduced as much as possible, generally about 15 cm, with a maximum not exceeding 18 cm.

5. Properly delay spring fertilizer and water management. Controlling the timing of fertilizer and water and the number of irrigations is the key to the success or failure of single-stem cultivation. For single-stem cultivated wheat, generally no topdressing or watering should be done before winter. After green-up, fertilizer and water should continue to be controlled until the jointing stage, when fertilizer and water are arranged according to seedling condition and growth vigor. For plots with low soil fertility and weak growth, fertilizer and water can be applied at the jointing stage in a timely manner. For high-fertility plots with strong seedling growth, fertilizer and water should be further delayed until the flag leaf tip emerges, with 15-25 kg of urea applied per mu. Topdressing should be combined with the first watering. If drought occurs, a second watering can be given at the flowering and grain-filling stage.

6. Do a good job in pest and disease control and later-stage foliar fertilizer spraying. Before sowing, all seeds should be treated with chemicals. In the later stage, combined with the control of ear aphids, potassium dihydrogen phosphate and photosynthetic micro-fertilizer should be used for foliar spraying to increase grain weight.