Abstract:

【Objective】To clarify the application effect and suitable substitution ratio of organic fertilizer for chemical fertilizer in the cultivation of sunflowers in the Hetao Irrigation Area.【Methods】The experiment was carried out in Linhe District,Bayannur City,Inner Mongolia. Six treatments,including 100% organic nitrogen(100% M),25% chemical fertilizer nitrogen+75% organic nitrogen(75% M),50% chemical fertilizer nitrogen+50% organic nitrogen(50% M),75% chemical fertilizer nitrogen+25% organic nitrogen(25% M),optimized chemical fertilizer(NE)and no nitrogen fertilizer(CK),were set up to establish the regression equation between the organic fertilizer substitution ratio and sunflower yield. Analyze the effects of different organic fertilizer substitution ratios on the crude fat content,fatty acid composition,grain rust,nitrogen utilization efficiency and soil nutrients.【Results】 Sunflower treated with 25%M had the maximum yield of 5 626.47 kg/hm² and was 30.70% greater than CK(P<0.05). According to regression analysis,the best substitution ratio for organic fertilizer in the cultivation of sunflowers was 18.86%. With an increase in the ratio of organic fertilizer substitution,the proportion of unsaturated fatty acids in sunflower seeds increased. Organic fertilizer substitute chemical fertilizer,the crude fat content of sunflower seeds marginally increased,while grain rust disease index and incidence rate dropped. 25%M treatment had the highest nitrogen fertilizer utilization rate and agronomic efficiency,which were 4.85 percentage point and 0.89 kg/kg higher than those of NE treatment,respectively. As the organic fertilizer substitution ratio increased,so did the contents of soil organic matter,available phosphorus,and available potassium.【Conclusion】When the optimal proportion of organic fertilizer substitution was 18.86%,the yield of sunflower was highest,the amount of crude fat and unsaturated fatty acids in the seeds increased,the disease index and incidence rate of grain rust decreased,and the nitrogen fertilizer utilization rate increased,soil enriched.

Key words: Sunflower, Organic fertilizer substitute chemical fertilizer, Substitution ratio, Yield, Nitrogen fertilizer utilization rate, Soil nutrients