%0 Research article
%T Adaptive responses to progressive drought stress in two Populus cathayana populations
%A Xiao, Xiangwen
%A Xu, Xiao
%A Yang, Fan
%D 2008
%J Silva Fennica
%V 42
%N 5
%R doi:10.14214/sf.224
%U https://silvafennica.fi/article/224
%X The young, vegetatively propagated cuttings of Populus cathayana Rehder  were exposed to a progressive drought stress for 12 weeks in a  greenhouse to characterize the physiological and biochemical basis of  drought adaptation in woody plants. Two contrasting populations were  employed in our study, which were from the wet and dry climate regions  in western China, respectively. The results showed that the adaptive  responses of P. cathayana to drought were affected by drought intensity  and poplar genotype (population). The progressive drought stress  significantly inhibited plant growth, increased carotenoid contents and,  at the same time, accumulated soluble sugars and free proline in the  plants of both populations tested. On the other hand, the gradually  increasing drought also induced antioxidative systems including the  increase of the activities of superoxide dismutase (SOD) and guaiacol  peroxidase (POD). Moreover, there were different responses to  progressive drought stress between the two contrasting populations.  Compared with the wet climate population, the dry climate population had  lower shoot height and growth rate, higher free proline content, and  more efficient photoprotective system (such as higher carotenoid content  and Car/Chl) and antioxidant system (such as higher POD activity), as a  result of drought stress. These results suggest that the dry climate  population possesses better drought tolerance than the wet climate  population. The differences in drought tolerance may be closely related  with efficient photoprotective system, accumulation of the  osmoprotectant proline as well as the increased capacity of the  antioxidative system to scavenge reactive oxygen species, and the  consequent suppressed level of lipid peroxidation under drought  conditions.