Leaf traits and photosynthetic characteristics of endangered Sinopodophyllum hexandrum (Royle) Ying under different light regimes in Southeastern Tibet Plateau.

Sinopodophyllum hexandrum (Royle) Ying, a medicinal plant, has been endangered due to alpine habitat and overuse at Southeastern Tibet Plateau. This study aimed to examine the phenotypic traits and photosynthesis of S. hexandrum, including their relationship with main environmental factors, under low light (LL), moderate light (ML), and high light (HL) regimes. Low specific leaf mass was observed under LL, but the stomatal density and apparent quantum yield were the highest under this regime. The phenotypic traits, except for stomatal density and net photosynthetic rate, were the most notable under ML. The leaf area, stomatal density, apparent quantum yield, dark respiration, and stomatal conductance showed the smallest values under HL. Air temperature, photosynthetically active radiation, and air vapour pressure deficit significantly affected the stomatal characteristics and photosynthesis of S. hexandrum individuals. Our results suggested that a moderately shaded habitat could promote leaf development and the photosynthetic ability of S. hexandrum. [ABSTRACT FROM AUTHOR]