Abstract: This paper studied the natural adaptation of photo-physiological, morphological, and developmental characteristics of Arabidopsis thaliana growing in arid and humid soil environments in northern piedmont of Tianshan Mountains. The results showed that the branch number, plant height, relative fitness (cornu-fruit mass), and rosette leaf area of A. thaliana in these two soil environments were significantly different. Root mass was positively correlated to relative fitness, rosette leaf area, water use efficiency, and photosynthesis rate, while intercellular carbon concentration was negatively correlated to photosynthesis rate and water use efficiency. The analysis of selection gradient indicated that plant height, branch number, and rosette leaf area were belonged to directional selection in arid and humid soil environments. Principal component analysis showed that the photo-physiological characteristics among treatments were conformed regularly, indicating that A. thaliana species would turn up homogeneous reaction when confronting environmental response. Path analysis suggested that the water use efficiency, branch mass, plant height, and cornu-fruit number were of direct path in the statistical model because of their strong effects on relative fitness, while rosette leaf area had effects on relative fitness via the indirect path of branch number, florescence, and cornu-fruit number.

Key words: Cucumber, Light intensity, Excess Mn, Photosynthesis, Chlorophyll fluorescence