Abstract:

【Objective】To find the optimum nitrogen application rate of Brassica oleracea var. capitata for high efficient cultivation in the cold area of central Inner Mongolia.【Methods】The total amount control experiment of nitrogen fertilizer for Brassica oleracea var. capitata was conducted in Wuchuan County，Inner Mongolia. Using Zhonggan 628 as the experimental variety，five different nitrogen application treatments were set up，including nitrogen free zone（T1），70% optimized nitrogen zone（T2），optimized nitrogen zone（T3），130% optimized nitrogen zone（T4）and 160% optimized nitrogen zone（T5）. The yield，commercial net vegetable rate，commercial characters and economic benefits of Brassica oleracea var. capitata under different treatments were compared and analyzed.【Results】The commercial net vegetable yield of T4 treatment was the highest at 96 878.8 kg/hm²，followed by T3 treatment at 96 313.1 kg/hm²，and increased by 27.78% and 27.03% respectively compared with T1 treatment. The commercial net vegetable rate of T3 treatment was the highest at 78.24%，followed by T2 treatment at 77.32%. The plant development increased as the nitrogen fertilizer application increased，with T5 treatment having the highest growth at 42.78 cm，18.24% higher than T1 treatment. The single bulb weight of commercial plant in T4 treatment was the highest at 2.10 kg，followed by T3 treatment at 1.99 kg，33.76% and 26.75% higher than that in T1 treatment，respectively. The net income added value of T3 treatment was the highest at 21 644.6 yuan/hm²，with a production ratio of 1.0∶7.4，followed by T4 treatment at 21 455.0 yuan/hm²，with a production ratio of 1.0∶5.6. The agronomic efficiency of nitrogen fertilizer in T3 treatment was the highest at 45.54 kg/kg，followed by T4 treatment at 36.00 kg/kg.【Conclusion】In order to promote the reduction of nitrogen fertilizer and increase nitrogen use efficiency，the optimal nitrogen fertilizer application rate of Brassica oleracea var. capitata in the cold area of central Inner Mongolia was 450 kg/hm².

Key words: Brassica oleracea var. capitata, Nitrogen fertilizer, Yield, Cold area, Central Inner Mongolia