Study On The Key Techniques Of High-yield Cultivation By Direct Seeding Of Rapeseed

In order to improve the yield of direct seeding rape per unit area, a research was conducted in a region of Liuyang where the rapes are direct seeded. It was studied that what influences the four factors which are different rape varieties, sowing time, herbicides and application of boron fertilizer have on the growth period, agronomic traits, pregnancy during flowering, yield and yield components factors as well as weed control and safety.This research has attained the following achievements:1. In the environment of high density cultivation, the growth period, the length of growth period, the agronomic traits, the yield components factors and the actual yield showed differences between rape varieties (or series) of C868,202, and Xiangyou No.15. The two early maturity varieties (or series), C868,202, was adapted to this kind of cultural environment, and C868 was better. However, the medium maturity variety, XiangyouNo.l5,was not giving full play to the advantages of high yield cultivation in this environment. Mainly, the reason is that yield components such as branch number and pod number were limited. In addition that the growth period was longer, therefore it is not suitable for Xiangyou No.15 to use as major cultivar of direct seeding.2. In are gion of Liuyang, on October 10 (B1), October 20 (B2)and October 30 (B3), rapes were direct seeded periodically. For the growth period of rape, the agronomic traits of seedling before winter, the yield components factors and the actual yield of rape seeds, the treatment of B1 was optimum, and that of B2 took the second place. In treatment of B3, these traits and factors were significantly declined, especially the actual yield of rape seeds. This shows that sowing rape between October 10 and October 20th can achieve the goal of high yield cultivation.3. Spraying S-metolachlorherbicide and 50% Napropamide in two days after the rape are seeded and during the seedling stage, theweed control effect is good, and no phytotoxicity to plants, safe to use. However, Although Acetochlor have a certainextent of weed control effect, but when it rains, and the field is filled with water, or soil is in a condition of excessive humidity, it is easy to cause the phytotoxicity, not safe to use.4. Applying borax in soil of direct seeding rape (C1), and spraying boron fertilizer during early flowering period and full-blossom period (C2), and duringearly flowering period, full-blossom period and final flowering period (C3), can improve the pregnancy of rape during the period of flowering, improving the structure of the agronomic traits and yield factor, and significantly increased the yield of rape seeds. But considering the actual situation of countryside, soil boron fertilizer shows the best economic benefits.Above all, in Liuyang rapeseed production areas, the way of using early maturity and high-yielding varieties, sowing between October 10th and 20th, and spraying S-metolachlor herbicide and 50% Napropamide for weed control and increasing boron fertilizer in the soil, is able to obtain high yield and high economic benefits.