Using a white maize(WM) cultivar and a yellow maize(YM) cultivar as the materials,we analyzed the changes in physiological characteristics and activity of plasma membrane(PM) H⁺-ATPase in the two maize cultivars treated with polyethylene glycol (PEG-6000) simulation drought stress under hydroponic conditions.The results indicated:(1)Under the treatment conditions of 2%,5% and 10% PEG-6000,with an increase in PEG-6000 concentration and treatment time,an elevation in the water loss rate,a decrease in leaf transpiration rate and stomatal conductance were observed in the two maize cultivars.Under all the same treatment conditions,the water loss rate in WM was less than that in YM,whereas,the reduction in leaf transpiration rate and stomatal conductance of WM were larger than those of YM,indicating that drought tolerant of WM was stronger than that of YM.(2)Under the same PEG-6000 treatment conditions,the leaf soluble protein,soluble sugar and free proline contents in WM were higher than those in YM,suggesting that osmotic regulation capacity of WM was larger than that of YM.(3)In the antioxidant enzyme system,with an increase in PEG-6000 stress concentration,CAT activity in both maize leaves display a decreasing pattern.Under 2% and 5% PEG-6000 stress conditions,the CAT activity in WM leaves was still significantly higher than that in YM leaves,which led to a significant lower H₂O₂ content in WM leaves than that in YM leaves.(4)Under drought stress conditions,the inhibition in the PM H⁺-ATPase phosphorylation level and its interaction with 14-3-3 protein in WM leaves were stronger than those in YM leaves.The PM H⁺-ATPase activity in WM leaves was lower than that in YM leaves.Consequently,the stomata aperture in WM leaves was less than that in YM leaves.Leaf transpiration rate and stomatal conductivity in WM were lower than those in YM leaves.This might be an important mechanism underlying the stronger drought tolerance in WM than that in YM.