Variation of the relative extractable soil water (%) during the experiment for the (A) well-watered and (B) water-deficit treatments. The symbols represent different population: the Danba population from a dry climate region (open circles), the Heishui population from a wet climate region (filled squares). F-values and significant levels of the factorial analysis (ANOVA): F_(p), the population effect; F_(t), the time effect; F_(p×t), the population×time interaction effect. ns, not significant.