Morphological and ecophysiological traits showed by male and female Populus tomentosa Carr. trees were studied under various degrees of water and alkaline stresses. The results showed that different adaptations to drought and alkaline stresses were adopted by each gender; males possessed a much higher tolerance to both stresses compared to females. In contrast to females, the males exhibited a lower inhibition in total biomass, total leaf area, net photosynthetic rate, stomatal conductance, leaf carbon and nitrogen concentrations as well as water- and nitrogen-use efficiency in response to drought and alkaline stresses. Nevertheless, compared to the males, the females showed a higher plasticity in root biomass/shoot biomass ratio, fine root/coarse root ratio, and intrinsic water-use efficiency, indicating that the males and females differed in some of trade-offs between growth and stress defence to maximize water and nitrogen gains under both stress conditions.