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.