Detailed Explanation of Key Points for Rapeseed Seedling Raising and Transplanting Techniques

Raising rapeseed seedlings and transplanting them makes full use of the light and temperature resources available before the late crop is harvested, cultivates strong seedlings, gives rapeseed sufficient growing time before winter so that strong seedlings overwinter, favors spring growth, and helps achieve high yields.
1. Use high-quality, high-yield varieties. Choose high-yield, high-quality rapeseed hybrid combinations or varieties, such as Ganyouza No. 1, Xiangzayou No. 1, Ganyou No. 17, Xiangyou No. 15, and so on.
2. Sow at the right time. For the sowing period of rapeseed, according to the length of the variety's growth period, the suitable sowing time for transplanted rapeseed is around September 20, and generally no later than the end of September.
3. Cultivate strong seedlings:
1. Seedbed preparation: At a ratio of seedbed to main field of 1:4-6, choose dry land with loose and fertile soil, convenient drainage and irrigation, flat terrain, and where no other rapeseed has been grown for more than two years as the seedbed. Before sowing, prepare the land finely so that the bed surface is level, the soil layer is fine and crumbly, and the top is loose while the bottom is firm.
2. Fertilize the seedbed: Per mu, use 1000-1200 kg of pig manure or 500-600 kg of human excrement and urine, 20-25 kg of ammonium bicarbonate, 20-25 kg of superphosphate, 5-6 kg of potassium chloride, and 0.5 kg of boron fertilizer, mix them evenly and compost for 7-10 days, then apply to the surface soil and mix evenly while preparing the bed as base fertilizer; screen the seeds, remove debris and shriveled grains, and treat each kg of seed with 20-30 g of 50% carbendazim wettable powder or 40% carbendazim suspension concentrate.
3. Sow an appropriate amount: Sow 400-500 g of rapeseed seed per mu of seedbed. To achieve even sowing, mix the seeds with plant ash or fine soil and sow a fixed amount per bed. After sowing, cover the seeds with burnt soil ash, splash on dilute liquid manure, and make it sparse, thin, even, and with the seeds not exposed. In dry weather, water with dilute manure water every evening to keep the surface soil moist; after emergence, persist in watering against drought, and furrow irrigation may also be used. Stop the water when it reaches 2/3 of the furrow, and drain the remaining water after the bed surface is moist.
4. Seedbed management: After emergence, thin the seedlings in time, thin again at the one-leaf stage, and set the final spacing before the three-leaf stage, removing small, mixed, diseased, and weak seedlings, thinning where dense and keeping where sparse, and at final spacing leave 70-100 plants evenly per square meter. At the three-leaf stage, spray 150 ppm paclobutrazol on the leaves (50 g of 15% paclobutrazol mixed with 50 kg of water) for chemical control, or use 40 ppm uniconazole for chemical control, to cultivate short and sturdy seedlings; if pests such as cabbage caterpillars, cutworms, and mole crickets cause damage, spray once with 800-1000 times diluted deltamethrin and phoxim. One week before transplanting, apply a send-off fertilizer, topdress with liquid manure and a small amount of urea solution (apply 2-4 kg of urea per mu), or supplement with a small amount of special fertilizer for the rapeseed seedling stage according to seedling growth.
4. Main field preparation and basal fertilizer application
1. Main field preparation: The previous crop of rapeseed can be rice, tuber crops, and so on, but overly loose sandy soil and overly heavy clay soil, poorly drained land, or paddy fields with deep mud are not suitable for growing rapeseed. When the previous crop is rice, drain the field water when the rice ears bend down, and after rice harvest plow and harrow the soil finely; for middle-season rice fields, sun-dry the soil until it turns white, irrigate once with a flash flow before land preparation, open a waist furrow in the middle of the field with a width and depth of 30 cm each, then divide into beds and prepare the land, with a bed surface width of 1.4 m, a furrow width of 30 cm, and a depth of 25 cm. When the previous crop is another dryland crop, after harvest deep plow 25-30 cm, harrow level and fine, remove volunteer rapeseed or other cruciferous crops, divide into beds and open furrows with a north-south bed direction, with a bed width of 2 m, a furrow width of 30 cm, and a depth of 20 cm, and open drainage ditches around the plot. Transplanting into rice stubble board fields can be done on alluvial land with a deep plow layer, making beds according to the above method and specifications, opening surrounding ditches and waist ditches, shoveling out the ditch soil, breaking it up, and spreading it evenly on the bed surface.
2. Basal fertilizer application: Rapeseed fertilization follows the principle of "heavy basal fertilizer, increased phosphate and potassium fertilizer, and mandatory boron fertilizer," with nitrogen fertilizer arranged in the ratio of "5 basal, 3 seedling, 2 bolting," 80% of potassium fertilizer as basal fertilizer and 20% as winter fertilizer, and phosphate and boron fertilizers applied all at once as basal fertilizer. Formula fertilization: follow the ratio of nitrogen, phosphorus, and potassium of 1:0.6:0.8, applying 10.5-14.5 kg of pure nitrogen, 6.8-9.5 kg of phosphorus pentoxide, 8.5-12 kg of potassium oxide, and 0.5-1.0 kg of borax per mu. Before transplanting, apply organic fertilizers such as human excrement and urine deeply as basal fertilizer. Generally, basal fertilizer uses 1200-1500 kg of pig and cattle pen manure per mu (or 1000-1200 kg of pig manure, or 1500-2000 kg of farmyard manure), mixed with 30 kg of compound fertilizer, 6-9 kg of superphosphate, and 8-12 kg of potassium chloride. If manure is used, add 2-3 cubic meters of fertile soil and mix evenly, compost for 10-15 days, and apply into the holes or planting furrows; when there is a lot of farmyard manure, it can also be applied to the surface first and then turned into the soil; when transplanting into board fields and using it as a root-covering fertilizer, it should be mixed with 500-550 kg of burnt soil ash or dry fine soil.
5. Transplant at the right age and with reasonable dense planting
1. Transplant at the right age with strong seedlings. The seedling age for transplanting is about 30 days, starting in mid-October and ending before the end of October as much as possible. The standard for strong seedlings is a seedling height of 16-18 cm, 6-7 green leaves, a root crown thickness of 0.5-0.6 cm, green color, thick leaves, short petioles, and no leggy seedlings. For double-cropping paddy field rapeseed, plant 6000-8000 plants per mu; for triple-cropping rapeseed, plant more than 8000 plants per mu.
2. Transplanting technique: On the afternoon of the day before transplanting, first splash the seedbed with dilute manure water so that roots are not damaged when seedlings are lifted and the seedlings have enough stored water. When transplanting, choose upright seedlings with well-developed root systems, symmetrical plant bodies, robust growth, and uniform size. First stand the plant upright in the center of the hole, fill soil around it and press firmly, then gently lift the plant upward once so that the lower roots spread out, which helps it turn green and survive. Immediately after transplanting, apply dilute manure water as settling water.