Elucidation of the adaptability of seedlings from different provenances analyzing photosynthetic characteristics and anatomical structure.

Understanding intraspecific variation in photosynthetic capacity and leaf structure is critical for optimizing provenance selection of in afforestation and urban landscaping programs. In this study, we assessed the adaptability of seedlings from four provenances (Fuzhou, Wuhan, Shenzhen, and Shanghai) by examining their physiological and anatomical traits under a common garden environment in Henan Province. A total of  = 80 three-year-old seedlings (twenty per provenance) were evaluated for photosynthetic parameters, stomatal characteristics, and leaf structural features. The results revealed that the net photosynthetic rates of seedlings from four different provenance sites exhibited a "double-peak" curve and a photosynthetic "lunch break" phenomenon, which was strongly positively correlated with stomatal conductance, transpiration rate, and Soil Plant Analysis Development (SPAD) value. Significant differences in stomatal characteristics were observed among the seedlings from four provenances. The seedlings from Fuzhou and Wuhan exhibited larger stomatal width, area, resulting in superior stomatal gas exchange than that in the seedlings from other provenances. Conversely, seedlings from Shanghai exhibited smaller stomatal area and density, indicating poorer gas exchange and reduced adaptability. The stem cortex cells, stem phloem, stem pith diameter, leaf palisade tissue thickness, and leaf thickness of the seedlings from Shanghai were significantly lower than those of the seedlings from other provenances, indicating that these structural characteristics do not exhibit any photosynthetic advantages over other provenances. In contrast, the seedlings from Fuzhou and Wuhan exhibited larger stem pith diameter, thicker mesophyll cell, and greater leaf thickness, which enhanced their photosynthetic capabilities. Among the seedlings from the four different origins, those from Fuzhou and Wuhan exhibited the best overall photosynthetic ability and strongest adaptability. Conversely, the seedlings from Shanghai exhibited the poorest overall photosynthetic ability and weakest adaptability. Despite similarities in climate, the environmental conditions of different provenances did not appear to have a significant correlation with leaf anatomy. This study provided valuable insights for the introduction of in various regions in China.