Effect of Nitrogen Application Rate on Dry Matter Accumulation and Distribution of Oil Flax

Field experiments were conducted to investigate the impact of different nitrogen( N) application rate on plant dry matter accumulation and distribution regulation as well as yield of oil flax. Results showed that the dry matter accumulation process accelerated with the increase of N application rate. The dry matter accumulation rate increased during the period from seedling stage to full flowering stage and decreased during the period from young fruit stage to ripping stage with the increase of N application rate. The maximum value of dry matter accumulation rate all appeared at full flowering stage under different N treatments. The dry matter accumulation finished ahead of time with the increase of N application rate. And the dry matter accumulation rate ranked top under middle N level. Applying N significantly influenced the dry matter distribution of shot growth period oil flax cultivars,but less obvious to the long growth period ones. Reasonable N application rate increased available pods and thousand-grain weight. The actual output per unit area was significantly positive with dry matter per plant. N use efficiency declined with the increase of N application rate. The optimal N application rate were 90. 0 kg / hm2in Zhangjiakou area and 36. 80 kg / hm2in Ordos area,respectively,increased oil flax yield by 30. 84% and 16. 84% compared with zero N application.