Effect of nitrogen fertilizer structure on the economic yield and quality of lettuce

The effect function of N application ratio during different growing periods of lettuce (Var. asparagina Bailey) was studied by the field experiments with 3,3 saturated design of single shape focus check. The results showed that better ratio of N application as basal dressing, early and late topdressing for higher expecting economical yield of 45.340 t·hm-2 were Z1 = 0.402, Z2 = 0.328, Z3 = 0.270, and the N rates were Z’1= 37.79 kg·hm-2, Z’2 = 30.83 kg·hm-2, Z’3 = 25. 38 kg·hm-2, respectively. Different nitrogenous fertilizer structure had no significant effect on soluble solids, reduced sugar, titratable acidity and nitrite content of lettuce, but had significant effect on total sugar, vitamin C and nitrate content.