Four-early management should be grasped well in direct-seeded rapeseed cultivation
Direct-seeded rapeseed should grasp the four earlies well
(Agricultural Wealth Network) As the area of the winter crop rapeseed expands year by year, the proportion of direct-seeded rapeseed has also increased. However, direct-seeded rapeseed is sown relatively late, and the effective growth period before winter is shortened, making it difficult to cultivate strong seedlings before winter. Therefore, the four-early management at the seedling stage must be grasped well.
Early thinning and final singling Direct-seeded rapeseed is sown at a relatively high seeding rate and sown relatively late, especially rapeseed in triple-cropping paddy fields, which is generally sown at the end of October. Improper thinning and fertilizer-water management often cause crowded seedlings, resulting in spindly and weak seedlings. Therefore, thinning should be carried out when rapeseed has 2~3 leaves, and final singling should be carried out at 4~5 leaves, moving dense seedlings to fill gaps to ensure a full stand, leaving 12,000~15,000 plants per mu, so that a relatively sufficient population makes up for the shortage of late sowing. After final singling, use 50 g of 15% paclobutrazol per mu, mixed with 50 kg of water for uniform spraying, to prevent tall-legged seedlings.
Early intertillage Weeding After final singling, intertill early and loosen the soil frequently. Especially for direct-seeded rapeseed on hardpan fields, the soil moisture is relatively high, the soil is compacted, and weed damage is relatively serious. The soil between rows and plants should be hoed fine and loosened, and weeds removed completely. Before low temperatures arrive, carry out one deep intertillage and earth up around the roots to keep warm and prevent freezing, promoting rapeseed root growth. In fields with many weeds, 80 mg of 20% napropamide per mu can be mixed with 50 kg of water and sprayed on stems and leaves to kill weeds, or 50 mL of 12.5% haloxyfop emulsifiable concentrate per mu can be mixed with 50 kg of water and evenly sprayed on weed stems and leaves, with relatively good results.
Early topdressing Promoting seedling growth On the basis of applying sufficient base fertilizer, generally apply growth-promoting fertilizer early after full emergence, using 4 kg of urea per mu mixed with water and splashed on. After each thinning, apply appropriate seedling-lifting fertilizer, using 5~10 loads of dilute human and livestock manure water per mu and splashing it on. After final singling, apply one strong-seedling fertilizer per mu, using 10 loads of human and livestock manure water and splashing it on. While applying nitrogen fertilizer, attention should also be paid to increasing phosphate and potassium fertilizer. Generally, apply 20 kg of superphosphate per mu, and in mid-December apply 20 loads of pig and cattle manure per mu as winter fertilizer to improve cold resistance. Topdressing is best applied in holes to reduce fertilizer volatilization losses. Direct-seeded rapeseed needs relatively more boron fertilizer, and is relatively sensitive at the seedling stage when boron is deficient. After final singling of rapeseed, 0.5 kg of borax fertilizer per mu can be mixed with water and sprayed.
Early prevention of early bolting and early flowering Because direct-seeded rapeseed has weak vegetative growth before winter, it is prone to early bolting and early flowering, which can be prevented and controlled according to the situation. First, for fields with relatively good growth and relatively sufficient fertility, carry out deep intertillage, loosening 7~10 cm deep near the rapeseed crown to cut off part of the root system and temporarily inhibit growth, then apply an appropriate amount of nitrogen fertilizer when the rapeseed begins to turn yellow. Second, for rapeseed with relatively poor growth, the method of heavily applying nitrogen fertilizer can be used, which can effectively delay vegetative growth, increase the amount of vegetative growth, and prevent early bolting. Third, for rapeseed fields that may bolt before the end of the year, promptly remove the bolt to inhibit the plant's apical dominance, so that nutrients are transferred from the main stem to the lower branches, delaying the reproductive process. After removing the bolt, promptly apply 15~20 loads of human and livestock manure water per mu, or 5 kg of urea mixed with water and splashed on, to promote branching.
Early thinning and final singling Direct-seeded rapeseed is sown at a relatively high seeding rate and sown relatively late, especially rapeseed in triple-cropping paddy fields, which is generally sown at the end of October. Improper thinning and fertilizer-water management often cause crowded seedlings, resulting in spindly and weak seedlings. Therefore, thinning should be carried out when rapeseed has 2~3 leaves, and final singling should be carried out at 4~5 leaves, moving dense seedlings to fill gaps to ensure a full stand, leaving 12,000~15,000 plants per mu, so that a relatively sufficient population makes up for the shortage of late sowing. After final singling, use 50 g of 15% paclobutrazol per mu, mixed with 50 kg of water for uniform spraying, to prevent tall-legged seedlings.
Early intertillage Weeding After final singling, intertill early and loosen the soil frequently. Especially for direct-seeded rapeseed on hardpan fields, the soil moisture is relatively high, the soil is compacted, and weed damage is relatively serious. The soil between rows and plants should be hoed fine and loosened, and weeds removed completely. Before low temperatures arrive, carry out one deep intertillage and earth up around the roots to keep warm and prevent freezing, promoting rapeseed root growth. In fields with many weeds, 80 mg of 20% napropamide per mu can be mixed with 50 kg of water and sprayed on stems and leaves to kill weeds, or 50 mL of 12.5% haloxyfop emulsifiable concentrate per mu can be mixed with 50 kg of water and evenly sprayed on weed stems and leaves, with relatively good results.
Early topdressing Promoting seedling growth On the basis of applying sufficient base fertilizer, generally apply growth-promoting fertilizer early after full emergence, using 4 kg of urea per mu mixed with water and splashed on. After each thinning, apply appropriate seedling-lifting fertilizer, using 5~10 loads of dilute human and livestock manure water per mu and splashing it on. After final singling, apply one strong-seedling fertilizer per mu, using 10 loads of human and livestock manure water and splashing it on. While applying nitrogen fertilizer, attention should also be paid to increasing phosphate and potassium fertilizer. Generally, apply 20 kg of superphosphate per mu, and in mid-December apply 20 loads of pig and cattle manure per mu as winter fertilizer to improve cold resistance. Topdressing is best applied in holes to reduce fertilizer volatilization losses. Direct-seeded rapeseed needs relatively more boron fertilizer, and is relatively sensitive at the seedling stage when boron is deficient. After final singling of rapeseed, 0.5 kg of borax fertilizer per mu can be mixed with water and sprayed.
Early prevention of early bolting and early flowering Because direct-seeded rapeseed has weak vegetative growth before winter, it is prone to early bolting and early flowering, which can be prevented and controlled according to the situation. First, for fields with relatively good growth and relatively sufficient fertility, carry out deep intertillage, loosening 7~10 cm deep near the rapeseed crown to cut off part of the root system and temporarily inhibit growth, then apply an appropriate amount of nitrogen fertilizer when the rapeseed begins to turn yellow. Second, for rapeseed with relatively poor growth, the method of heavily applying nitrogen fertilizer can be used, which can effectively delay vegetative growth, increase the amount of vegetative growth, and prevent early bolting. Third, for rapeseed fields that may bolt before the end of the year, promptly remove the bolt to inhibit the plant's apical dominance, so that nutrients are transferred from the main stem to the lower branches, delaying the reproductive process. After removing the bolt, promptly apply 15~20 loads of human and livestock manure water per mu, or 5 kg of urea mixed with water and splashed on, to promote branching.