关键词: 油菜, 产量, 品种, 菌核病, 氟唑菌酰羟胺, 种子处理, 越冬调控

Abstract:

【Objective】Rapeseed (Brassica napus L.) is the first major oil-bearing crop in China. Enhancing rapeseed yield per unit area is the key to increase its effective supply and economic benefits. Under the condition of mechanical direct seeding, further clarifying the impacts of major technical factors, such as variety selection, overwintering regulation, and disease and pest control, on the yield per unit area could provide a theoretical basis for the improvement of rapeseed yield per unit area in China. 【Method】Nine high-yield and high-quality rapeseed varieties were selected, and mechanical direct-seeding experiments were conducted at 22 experimental sites (major rapeseed-producing counties) over 2 years from 2021 to 2023. A systematic study was carried out to investigate the impacts of factors such as rapeseed variety, seed treatment, overwintering regulation, and Sclerotinia sclerotiorum control on the yield per unit area under the condition of reduced topdressing application of nitrogen fertilizer. 【Result】The application of three combined treatment techniques, namely seed treatment (Maishuping coating for pest prevention, D1), overwintering regulation (D2), and novel Sclerotinia sclerotiorum control (fluxapyroxad, D3), all significantly increased the yield per unit area of rapeseed under reduced nitrogen topdressing (urea 45 kg·hm^-2). Compared with the traditional loss-reduction technology mode (uncoated seeds+no overwintering regulation and prochloraz for Sclerotinia sclerotiorum control+urea topdressing, CK), with a yield of 112.5 kg·hm^-2, the yields under D1, D2 and D3 treatments increased significantly by 6.2%, 6.4%, and 10.9%, respectively, while the corresponding yields reached 2 594.2, 2 600.4 and 2 708.9 kg·hm^-2, respectively. However, only the incidence of Sclerotinia sclerotiorum was extremely significantly reduced by 49.1% under the D3 treatment. Different technical combinations exhibited significant interaction effects on yield per unit area improvement. When seed treatment and overwintering regulation were combined with the novel Sclerotinia sclerotiorum control technology respectively, the yields were significantly 15.7% and 16.1% higher than those under the traditional technology, respectively, reaching 2 820.0 and 2 834.2 kg·hm^-2, respectively, while the incidence of Sclerotinia sclerotiorum decreased by 55.6% and 55.3%, respectively. Additionally, there was a significant interaction effect between rapeseed variety genotypes and technology. The application of new technologies could exceed the national regional trial yields of the corresponding varieties. For instance, the regional trial yields of Yangguang 131, Dadi 199 and Zhongyouza 39 were 2 341.2, 3 085.5, and 2 982.0 kg·hm^-2, respectively. Under optimized combinations of regulatory technology, the yields were 11.7%, 5.0% and 3.5% higher than their respective regional trial yields, respectively. A multiple stepwise regression analysis was conducted between the experimental yield and factors including the regional trial yield, disease resistance of rapeseed varieties, as well as different technological combinations, and the results revealed that the critical factors determining yield levels were the 1000-seed weight in regional trials, regional trial yield of varieties, novel Sclerotinia sclerotiorum control, and reduced winter urea topdressing rate. Canonical correlation analysis further confirmed that the regional trial yield, regional trial 1000-seed weight, and regional trial silique number of varieties determined the yield levels. Meanwhile, fluxapyroxad and Maishuping played a very important role in enhancing yield increase rates. Additionally, the novel Sclerotinia sclerotiorum control technology and overwintering stress resistance regulation were related to reducing the incidence of Sclerotinia sclerotiorum. 【Conclusion】In the mechanical production of rapeseed, the regional trial yield of varieties was a key factor affecting the rapeseed yield levels. The use of fluxapyroxad to control Sclerotinia sclerotiorum was an effective factor for reducing the yield loss caused by Sclerotinia sclerotiorum at present. The combination of seed treatment, overwintering regulation and the novel Sclerotinia sclerotiorum control technology could further exert the yield potential of rapeseed varieties. It was suggested that in practical production, high-yield and high-quality varieties should be selected, and loss-reduction technologies, such as supporting seed treatment, overwintering regulation and fluxapyroxad, should be matched to achieve a significant improvement in rapeseed yield per unit area.

Key words: rapeseed, yield, variety, Sclerotium disease, pydiflumetofen, seed treatment, over-winter regulation