Growth and Yield Formation of Direct-Seeding Rapeseed Under No-Tillage Cultivation in Double Rice Cropping Area in Hubei Province

In the Yangtze River basin, winter fallow is popular for the double cropping rice (Oryza sativa L.). In this study, the possibility of adding a rapeseed cropping season after late rice harvest in this area was studied with the purpose of extending direct-seeding rapeseed under no-tillage cultivation pattern. In a 2-year field experiment from 2008 to 2010, the rapeseed cultivar Huashuang 5 (Brassica napus L. cv. Huashuang 5) were planted in 3 locations in Hubei Province of China after harvesting late rice. At both individual and population levels, the effects of plant density and nitrogen (N) application rate on rapeseed growth and yield formation were measured at seedling, budding, flowering, podding, and maturity stages. The cultivation pattern of no-tillage and direct-seeding after late rice harvest shortened the growth duration of rapeseed, especially at seedling stage, but prolonged the late budding stage in spring. The biomass accumulation from emergence to early budding was deficient severely, resulting in quick growth from budding to flowering of rapeseed. Application of N fertilizer had significant effects on enhancing the growth and yield formation of rapeseed through improving the individual and population qualities. Under the N rate of 270 kg ha−1 condition, the highest yield of rapeseed was approximately 2250 kg ha−1 at the density of 4.5 × 105 plants or 6.0 × 105 plants per hectare. The yield level was higher than that of average local rapeseed production. In the practice of no-tillage and direct seeding cultivation technique in the double rice cropping rice area, both nitrogen application rate and planting density should be considered simultaneously to obtain high quality of plant population and high yield of rapeseed.

摘 要长江流域双季稻区因茬口紧、土壤黏重, 晚稻收获后大都未种植下茬作物而形成冬闲田。本研究以华双5号油菜品种为材料, 在湖北双季稻区三试验点进行裂区试验, 测定油菜各生育期在不同氮素及密度水平下的个体及群体指标, 成熟期考察经济性状及产量构成, 为双季稻区免耕直播油菜示范及管理提供依据。结果表明: 双季稻区免耕直播油菜全生育期尤其是苗期显著缩短, 苗期生长量严重不足, 蕾薹期至开花期油菜生长快, 春发特性明显; 氮肥及种植密度水平对双季稻区免耕直播油菜生长及产量有着显著影响, 增施氮肥可改善个体素质、增加产量, 提高密度可提高群体素质、增加产量; 湖北各试点每公顷纯氮用量270 kg、种植密度为45万株及60万株处理的产量均接近或达到2 250 kg ha−1北平均单产, 说明油菜免耕直播栽培模式可在湖北双季稻区试验示范。生产实践中, 应重视氮肥与密度的双重调节, 以肥促长、以密补迟, 相互配合。