Abstract: In hydroponics,the treatment of partial(20%) replacement of nitrate by amino acid can improve the quality of the lettuce obviously and can reduce the nitrate content of the lettuce especially.But,Amino acid will be decomposed by microbes when they stay in solution too long,so the plant's assimilating efficiency is low.In order to solve this problem,we studied the effect of different fertilization ways of amino acid and the sterilization ways of nutrient solution on the production and the quality of the lettuce in hydroponics when the 20% nitrate of solution were replaced by mixed amino acid.This experiment was done 12 days before harvest and we designed 4 treatments:A,All the amino acid was added to solution 1 time;B,All amino acid was divided four times to add to solution,1 time per 3 days;C,All the amino acid was divided four times to add to solution as that of treatment B,but every time before the amino acid was added,we sterilized the solution for half an hour by releasing ozone;D,All the amino acid was divided four times to add to solution as that of treatment B,but every time before the amino acid was added,we sterilized the solution for 10 minutes by heating the solution up 60-70℃.The results are as follows:the way of fertilization 1 time is prior to the way of fertilization several times when the nutrient solution was not been sterilized; The production and the quality of the lettuce in sterilized nutrient solution will be higher than that of the lettuce in the fertilized nutrient solution;The way of sterilization by heating is prior to the way of sterilization by re-leasing ozone.The difference of the effect of the two ways of sterilization by heating and releasing ozone on the lettuce is not evident.

Key words: Amino acid, Fertilization ways, Nutrient solution, Sterilization ways, Lettuce, Production and quality

CLC Number: 

• S636.2