A composite model including crop leaf area index and water uptake was used to count tomato
plant daily water requirement quantity．Four different irrigation treatments were established（CK Experience
irrigation，W1 Equals simulation，W2 15% Lower than simulation，W3 25% Lower than simulation）to study
the effect of model simulation water requirement on tomato growth，yield，fruit quality and water use efficiency in
substrate culture with bag．The results indicated that the tomato plant height，stem diameter，fruit diameter，
photosynthetic rate and top dry weight declined along with the decrease of irrigation quantity．Under CK
treatment，the single plant yield was the highest（4.66 kg），which was 4.3%，23.3% and 47.9% higher than
that of W1，W2，and W3 treatmens，respectively，but the difference was not significant with W1 treatment．
The soluble sugar，sugar acid ratio，VC content were increased and the fruit quality was improved，along with
suitable reducing the irrigation quantity，wherein the W3 treatment was the best，W1 treatment took the second
place．Under W1 treatment，the water use efficiency was the highest（51.76 kg·m^-3），which was 10.3%，0.6%
and 5.9% higher than that of W1，W2，W3 treatments，respectively．In this experiment，W1 treatment，on the
basis of guaranteeing fruit yield and quality，has greatly improved the water use efficiency．The composite model
is suitable for water management application in tomato substrate cultivation.