Physiological and Biochemical Responses of Salvia przewalskii to Altitude Gradient in Subalpine Area of Western Sichuan
[Objective]Explore the physiological and ecological response patterns of Salvia przewalskii to changes of altitude,providing a reference basis for efficient prediction of plant responses and adaptive changes under climate change.[Methods]S.przewalskii was selected as the research material from six altitudes(2 400,2 600,2 800,3 000,3 200,3 400 m)in the subalpine area of Western Sichuan.Gas exchange and biochemical technologies were utilized to measure the physiological and biochemical parameters of leaves such as photosynthetic characteristics,non-structural carbohydrates,malondialdehyde,proline,and antioxidant enzymes.Comprehensive comparison and analyses were conducted to explore the changes and correlations of these indicators along altitudes.[Results]With rising altitude,the net photosynthetic rate under light saturation,stomatal conductance,intercellular CO2 concentration,transpiration rate,starch,soluble sugars,non-structural carbohydrates,and proline of S.przewalskii showed an overall trend of first increase and then decrease,and they showed maximum values at 2800 m.Compared to the lowest altitude,the values of those parameters at 2800 m were increased by 30.3％,78.7％,7.6％,23.0％,42.9％,30.1％,37.4％,and 48.7％,respectively.Malondialdehyde,superoxide dismutase,peroxidase,catalase,and ascorbate peroxidase showed an overall trend of first decrease and then increase,and they showed minimum values at 2800 m.Compared to the lowest altitude,the values of those parameters at 2 800 m were decreased by 16.2％,12.5％,25.4％,6.4％,and 11.3％,respectively.The light compensation point and light saturation point increased with rising altitude.The physiological and biochemical characteristics of leaves exhibited a strong plasticity with a range of 0.02～0.56.Altitude was significantly positively correlated with the net photosynthetic rate under light saturation(P＜0.01),stomatal conductance(P＜0.05),light compensation point(P＜0.01),soluble sugars(P＜0.05),non-structural carbohydrates(P＜0.05),malondialdehyde(P＜0.01),proline(P＜0.05),superoxide dismutase(P＜0.01),peroxidase(P＜0.01),catalase(P＜0.01),and ascorbate peroxidase(P＜0.01),while significantly negatively correlated with the transpiration rate(P＜0.01).[Conclusion]In response to different altitude,S.przewalskii adjusted physiological and biochemical characteristics of leaves.High or low altitudes limited carbon assimilation of leaves.To ensure normal growth and development,plants optimized resource allocation to balance growth and survival,and maintained net carbon gain.
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