3.1 Growth and physiological traits
The factor of seed source had significant effects on the number of tillers, plant height, aboveground biomass, belowground biomass and Pn. In detail, each growth trait of individuals from the western region was significantly lower than those from the other two regions (Table 2).
The factor of soil moisture had significant effects on all traits. In detail, each trait of individuals under heavy drought treatment was significantly lower than those under the other two soil moisture treatments (Table 2).
The interaction between seed source and soil moisture had significant effects on Pn, Tr and Gs. Pn, Tr and Gs of individuals from the middle region were higher under light drought treatment than under control. Under the heavy drought treatment, the Pn of individuals from the western region was significantly greater than that from the other two regions (Table 2).