Height increment in two contrasting populations of P. asperata as affected by exogenous ABA application. (A) The Heishui population from a wet climate region; (B) the Danba population from a dry climate region. The vertical lines represent SE. The values are means ±SE, n=20. Treatments: –ABA+WW, non-ABA application+well-watered; +ABA+WW, ABA application+well-watered; –ABA+D, non-ABA application+water deficit; +ABA+D, ABA application+water deficit. Different letters on the right denote statistical differences (P <0.05) according to the Tukey's test.