Abstract：Under the condition of root restriction cultivation，taking normal drainage （20-EC1.6
treatment）as the contrast，this paper measured tomato growth indexes,leaf photosynthetic parameters，
fruit commodity characters，related metabolic enzymes and primary metabolites，etc. under the conditions of
minimal drainage（0-EC1.6 treatment） and increasing nutrient solution concentration（0-EC1.6-2.4 treatment）
or adding NaCl（0-EC1.6-2.4Na treatment） and studied the effect of extremely low drainage rate（ELDR）
and nutrient concentration regulating on tomato fruit quality．The results showed that ELDR could significantly
inhibit tomato plant stem thickening，leaf extension and fruit expanding，decreased leaf net photosynthetic
rate（Pn），stomatal conductance（Gs），intercellular CO2 concentration（Ci），transpiration rate（Tr），
single fruit weight and yield per plant．However，the contents of soluble solid matter，VC，lycopene，
polyphenols，free amino acid and glucose/malic acid，fructose/citric acid in fruit were significantly increased，
while the percentage of non-commercial fruit was decreased．ELDR combined with increasing nutrient solution
concentration could further increase the contents of soluble solid matter, amino acid and its ramification
（5-L-glutamyl-L-alanine），phenolic acid（coumaric aldehyde）and glucose/malic acid；and reduced noncommercial
fruit rate．ELDR could significantly increase the activities of invertin and sucrose synthase，which
were further remarkably increased by increasing nutrient solution concentration．Thus，catalytic decomposition
of sucrose was made to produce glucose and fructose．Comprehensively considering various indexes，0-EC1.6-2.4
was the optimum treatment for improving tomato fruit quality under root restriction cultivation condition．
