Effects of cultivation pattern on growth, seed yield, nutrient uptake and utilization of direct-sowing oilseed rape (Brassica napus L.)

The directsowing cultivation has played an important role in increasing planting areas and total production of oilseed rape in China. However, the lagging cultivation and fertilization techniques restrict greatly rapeseed yield and fertilizer use efficiency. Two field experiments were therefore conducted in the main oilseed rape planting areas of Hubei province during 2009/2010. The objective of this study is to investigate the effects of different cultivation patterns on growth, seed yield, economic benefit, nutrient uptake and fertilizer use efficiency of direct sowing oilseed rape, and thereby to summarize the key techniques of high yield and high efficiency cultivation under current production conditions. The results show that the optimized cultivation pattern (OCP) has higher rapeseed yield than that of the farmers practice pattern (FFP), and the best performance is observed in the OCP Ⅲ treatment. With this cultivation pattern, reasonable fertilization measures (N 195 kg/ha, P2O5 90 kg/ha, K2O 90 kg/ha and Broax 15 kg/ha were applied, and N and K fertilizers were applied in splits) are implemented on the basis of increasing appropriately plant density (30104 plant/ha), using straw returning and enhancing plant protection to pest, disease and weed. The rapeseed yield and net benefit are increased by 35.9 % and 1632 Yuan/ha in the OCP Ⅲ treatment compared with the FFP treatment. In addition, the aboveground dry matter and nutrient accumulation amounts in the OCP Ⅲ are also significantly improved, and the mean N and K fertilizer efficiencies (PFP) are N 13.7 kg/kg and K2O 29.8 kg/kg, respectively. Hence, the OCP Ⅲ is considered as a better practice to achieve high yield and high efficiency of directsowing oilseed rape in present research. The results from this study indicate that cultivation management should be accord with the growth process and nutrient uptake regulation of directsowing oilseed rape. With this principle, we should increase appropriately planting density to enlarge source and sink of oilseed rape, whilst enhance plant protection to control pest, disease and weed. And more importantly, optimal fertilization measures should be used, including balanced fertilization, applying inorganic fertilizer combined with organic manure, and reasonably arranged fertilization time and ratio.