Effect of Different Nitrogen Fertilizer Level on Yield and Quality of Lettuce

A pot experiment was conducted to study the effects of different nitrogen fertilizer level on the yield and quality of lettuce.The result showed that there was significant difference between the yield of lettuce.The yield of lettuce was significantly increased by 56.2%～161.0% with the application of N fertilizer,and the effect of N3 was the largest(161.0%).The content of chlorophyll a,chlorophyll b,chlorophyll a+b and a/b were increased by 154.2%～420.3%,72.1%～287.9%,25.0%～372.8 and 34.1%～47.2%,respectively.Compared with CK,the content of vitamin C of lettuce was enhanced by 61.6%~161.6%,but the nitrate concentration was decreased by 16.4% in N3treatmnt,improved by 60.0% and 44.2% in N1 and N3 treatments.The soluble sugars content was increased by 24.7%in N1 treatment and reduced by 9% in N3treatment,but in N2 treatment the effect was little.The amino acids content was increased by 14.6% and 34.9% in N1and N2 treatment.Taking yield and quality into consideration,N3 treatment was best.