Effects Of Nitrogen Nutrition On Growth And Yield Formation Of Oil Flax

Oil flax is one of the main oil crops in China,the average of acreage and production rank the third and the second in the world.But the yield per unit area is only 78.65% and 78.77% of that of the United States and Canada.Superficial studys on nutrition requirement and fertilization technology of oil flax in China is one of most important reasons for lower yield.In view of the fact,sand and soil pot experiments were used to study the effects of nitrogen supply,the most importmant nutrient factor which limits plant growth and grain yield formation,on growth,nutrient accumalation and yield formation of oil flax.The results are as follows:1.Nitrogen(N)deficiency in different stages impacted on oil flax growth,due to the deficiency period.Deficiency in Sowing-fir-shaped(T1),fir-shaped squaring(T2)shortened the growth duration 11 and 28 days respectively compared with the CK(supply N in the whole growth duration),but didn't influence the reproductive process of oil flax.N deficiency before and after budding resulted in obvious symptom in leaves.Among the six treatments,i.e.T1,T2,T3(budding-full bloom),T4(full bloom-mature)and T5(budding-mature),the most serious symptom occurred in T2 treatmeat.2.Compared with no fertilizing,0.1 and 0.2 g N/kg soil incread N accumulation in whole plant by 29.07% and 64.38%,Phosphorus by 25.37% and 75.84%,potassium by 23.81% and 48.08%,indicating that nutrition improvement increased with the increase of N dosage.When N dosage was 0.2 g N/kg soil,among the five treatments,i.e.100% basal(B),2/3 basal + 1/ 3 dressing in budding stage(C),1/2 basal + 1/2 squaring dressing in budding stage(D),1/6 basal+5/6 dressing in fir-shaped stage(E)and 1/6 basal +2/6 dressing in fir-shaped stage +3/6 squaring top dressing in budding stage(F),F increased N accumulation by 15.76% ~ 38.71%,phosphorus by 9.54% ~ 23.67% and potassium by 9.79% ~ 31.18% comoared with the other treatments,F was the best N application pattern.3.In capsuliferous stage,compared with the treatments B,C,D and E,F increased nitrogen metabolites content in leaves,decreased glutamine synthetase activity,and retarded the conversion from inorganic nitrogen to organic nitrogen.In addition,F decreased the content of reducing sugars,sucrose,starch and soluble sugar,which improved the transformation of carbon metabolites from leaves to grains.4.Compared with supplying nitrogen in the whole growth period,nitrogen deficiency in the following stages,i.e.sowing to fir-shaped,fir-shaped to budding,budding to fully flowering,fully flowering to maturation and budding to maturation,decreased grain yield by 18%,27%,35%,39% and 48% respectively.The decrease due to nitrogen deficiency in reproductive growth stage was significant than that in vegetative growth stage.Nitrogen fertilization increased grain yield significantly under low soil fertility condition.Compared with no fertilizing,0.1 and 0.2 g N/kg soil increased grain yield by 30% and 8.33%~33.33%.When N dosage was 0.2 g N/kg soil,among the five combinations of application time,fertilizing three times had the best yiled improvement,and its grain yield increased by 6.67%~33.33%% than that of the other four treatmens.