This paper studied the effects of nutrient solution pH and salt interaction stress on ginger yield
and quality by quadratic saturation D-optimization design，and established dyadic and square mathematical
models with pH and salt dosage as variable factors and ginger yield and quality as objective function．The
model analysis indicated that pH and salt content had significant interaction effect on ginger yield and quality．
Salt content was the dominant factor for yield；pH was the dominant factor for quality．Low level pH change
had no significant effect on ginger yield．When pH rised to 7.70，the ginger yield showed a rapid downtrend
along with the rise of pH．While along with the increase of salt content，ginger yield continued to decrease．
Along with the rise of pH，ginger quality showed a slow decrease tendency．When salt content was lower than
77.91 mmol · L^-1，the ginger quality went up along with the increase of salt content，later the ginger quality
went down along with the increase of salt content．