Physiological responses and drought resistance evaluation of 12 plants to drought stress and rehydration in the northern piedmont of Tianshan Mountains in Xinjiang

[ Objective ] The front piedmont belt of the northern slope of the Tianshan Mountains in Xinjiang is a crucial component of the mountain-oasis-desert ecosystem of the Tianshan northern slope. Investiga- ting the dynamic physiological adaptations of plants to drought stress and assessing methods for drought resistance , as well as selecting suitable tree species for vegetation restoration holds significant importance for the ecological restoration in this region. [ Methods ] 12 plant species planted in the piedmont belt of the northern slope of the Tianshan Mountains in Xinjiang were selected as the subjects. The study observed the spatiotemporal distribution of soil moisture following irrigation and analyzed the impact of drought stress and rewatering treatment on plant photosynthetic and physiological indicators. The drought resist- ance of these 12 species was evaluated using principal component analysis. [ Results ] ( 1 ) Following drought stress , soil moisture depletion occurred most rapidly in the 0-20 cm layer , followed by the 20- 40 cm layer , and was slowest in the 40-60 cm layer. Different plants employed different strategies to adapt their growth to drought stress. ( 2 ) Following drought stress , net photosynthetic rate ( P n ), stoma- tal conductance ( G s ), transpiration rate ( T r ), intercellular CO 2 concentration ( C i ), potential activity of PSⅡ ( F v / F o ), maximum photochemical efficiency of PSⅡ ( F v / F m ), electron transport rate ( ETR ), and chlorophyll content were decreased , while the activity of superoxide dismutase ( SOD ), proline content , malondialdehyde ( MDA ) content , and non-photochemical quenching coefficient ( q N ) were increased. Af- ter rehydration , there was a certain degree of recovery in each parameter , but none of them reached the in- itial levels. ( 3 ) The results of principal component analysis highlighted that factors like P n , chlorophyll content , ETR , and MDA content were major contributors. Species such as Haloxylon ammodendron , Tamarix chinensis , Rosa acicularis , and Caragana korshinskii demonstrated significant drought resili- ence. Hippophae rhamnoides , H . rhamnoides ‘ Xinji 5 ’, H . rhamnoides ‘ Xinji 1 ’, and Prunus sibirica showed moderate levels of drought resistance , while H . rhamnoides ‘ Xinji 4 ’, H . rhamnoides ‘ Xinji 3 ’, Xanthoceras sorbifolium , and H . rhamnoides ‘ Xinji 2 ’ exhibited relatively lower drought tolerance. [ Conclusion ] P n , chlorophyll content , ETR , and MDA content were crucial indicators for evaluating the adaptability of various plant species to drought stress. In the context of ecological restoration efforts in the piedmont belt of the Tianshan Mountains􀆴 northern slope in Xinjiang , prioritizing the cultivation of H . ammodendron , T . chinensis , R . acicularis , and C . korshinskii were recommended.