Study on Effect of Applying Ratio of Nitrogen to Potassium on Quality of Lettuce

[Objective] The study was to provide the theoretical basis for producing leaf vegetables with high quality and high yield.[Method] 4 fertilizer treatments were designed in pot experiment.The yield of each pot,the contents of the nitrate,Vc,amino acids and soluble sugar of lettuce were detected after harvest.[Result] The yields of lettuce among different fertilization treatments had extremely significant difference.The yields of lettuce could raise 13.9%-51.0% when the N and K application were increased,the treatment with 200 mg/kg N and 100 mg/kg K increased the yield to greatest extent(51.0%).N increasing application could decrease Vc content of 6.7%-10.1% and increase the amino acids content of 24.9%-44.8% in lettuce,and it had different effect on the nitrate and the soluble sugars.K increasing application could increase 22.7% of nitrate content and decrease the content of the amino acids and the soluble sugars of 15.2% and 19.9% resp,and it had little effect on Vc content.[Conclusion] Considering from the yield and quality of lettuce,the treatment of 200 mg/kg N and 100 mg/kg K had the best comprehensive effect on lettuce,so that it was the optimal treatment.