Instantaneous water use efficiency of E. angustifolia showed the tendency of increase-decrease-increase, but G. biloba G.Don var. parviflora always decreased.

• (2)随着干旱胁迫增加，沙枣瞬时水分利用效率呈现增加-下降-再增加趋势，孩儿拳头呈现下降趋势；