The Latest Complete-Stand Method for High-Yield Direct-Seeded Rapeseed Cultivation

Compared with seedling raising and transplanting, direct-seeded rapeseed cultivation omits such steps as raising seedlings, pulling seedlings, transplanting seedlings and watering for root establishment, reduces labor input, lowers labor intensity and production costs, and has no seedling revival period; under the conditions of adopting supporting cultivation measures, the yield of direct-seeded rapeseed can be equal to that of seedling raising and transplanting.

Cultivation Techniques

1. Arrange the preceding crop well. The preceding crop must not be a variety with too long a growth period or too late maturity.

2. Variety selection. Choose double-low rapeseed varieties that are early-maturing and tolerant of late sowing, with strong seed germination vigor, good lodging resistance, a long main inflorescence, a compact plant type and strong disease resistance.

3. Field preparation. After the preceding crop is harvested promptly on a sunny day, apply base fertilizer immediately and open the “three ditches” well; sow immediately when there is sufficient soil moisture or on a rainy day. Use ammoniacal nitrogen cautiously in the base fertilizer to avoid burning the sprouts and seedlings.

4. Seed treatment and sowing. In the Yangtze River Basin, the suitable sowing period is September 20 to 30, and no later than mid-October. At sowing, thoroughly mix each 1 kg of seed with sieved dry soil manure and 15% paclobutrazol 1.5 g (to prevent leggy seedlings); sow when there is no standing water in the field and the soil does not sink underfoot, generally using 0.2 to 0.3 kg of seed per mu. If dry weather occurs after sowing, furrow irrigation may be used to resist drought and promote emergence, but flooding irrigation over the bed surface is strictly prohibited.

5. Chemical weed control. According to the distribution of weed communities in the previous year, do a good job at the three weed-control stages: before sowing, after sowing but before emergence, and at the seedling stage.

6. Fertilizer management. Follow the principles of applying sufficient base fertilizer, applying seedling-promoting fertilizer according to seedling condition, and applying bolting fertilizer early. Per mu, apply 15 to 18 kg of pure nitrogen, 8 to 10 kg of phosphorus pentoxide, 8 to 12 kg of potassium oxide, and 1 to 1.5 kg of borax. Phosphate, potash and boron fertilizers are all used as base fertilizer. 50% of the nitrogen fertilizer is used as base fertilizer, 20% as winter fertilizer or early-spring relay fertilizer, and 30% as bolting fertilizer, applied as soon as buds appear (when the bolt is 3 to 5 cm high).

7. Field management. Direct-seeded rapeseed can be thinned and set in place when it has 1 to 2 true leaves, removing small ones and keeping large ones, removing mixed ones and keeping pure ones; for vigorously growing fields, 30 to 50 g of paclobutrazol per mu should be used in mid-to-late November for chemical regulation; if leaf color turns yellow at the seedling stage and new leaves emerge slowly, apply 3 to 6 kg of urea per mu as a seedling-promoting fertilizer according to soil moisture; do a good job in drought resistance, waterlogging prevention, and disease and pest control.

8. Timely harvest. The suitable harvest time is about 30 days after rapeseed finishes flowering. It is advisable to harvest when 2/3 of the siliques in the whole field are yellow-green, the siliques in the middle of the main axis are loquat-colored, and 1/3 of the siliques on the whole plant are still green. For fields harvested mechanically, the harvest time should be delayed by 3 to 5 days. The suitable harvest period for rapeseed is relatively short, so the timing must be grasped well and the harvest rushed on sunny days.

Suitable Regions

Where the cropping sequence permits, this technique can be adopted in all rapeseed-producing regions of China.

Precautions

1. Determine the suitable sowing rate according to soil fertility and moisture conditions. If the soil condition is poor, the sowing rate should be increased.

2. Ensure a suitable planting density, generally 25,000 to 30,000 plants per mu.

3. Check seedlings in time, thinning where too dense and filling gaps where missing, and the earlier the better.

4. Ensure the “three ditches” are unobstructed, and do a good job in controlling sclerotinia during the flowering period.