EFFECTS OF DIFFERENT SHADING CONDITIONS ON THE GROWTH, PHOTOSYNTHETIC CHARACTERISTICS AND LEAF STRUCTURE OF FIRMIANA KWANGSIENSIS SAPLINGS

To determine the optimal light environment for Firmiana kwangsiensis saplings, the growth characteristics and physiological traits of the saplings in environments shaded in different ways were compared with those in the full light environment as a control in this paper.The study revealed that F. kwangsiensis saplings showed significantly higher ground diameter, radiation area of the root, and fresh weight under 25% shading rate.The chlorophyll a, chlorophyll b, and total amount and ratio of both chlorophylls displayed a decreasing trend with the reduction of shading intensity.The photosynthetic physiological parameters, including maximum net photosynthetic rate (Pmax) and net photosynthetic rate (Pn), etc. of F. kwangsiensis saplings under 25% shading condition were higher than that in other treatments.The density of stomata, palisade tissue, spongy tissue, and leaf thickness of leaves increased with higher light intensity.The leaves of saplings under full light condition displayed a "double-layer palisade tissue" structure with drought-resistant properties.The results of correlation analysis showed that photosynthetic physiological characteristics and leaf anatomical structure had the greatest influence on the growth of F. kwangsiensis saplings.In summary, F. kwangsiensis saplings thrive in shaded environments, with a 25% shading being particularly optimal for their growth.However, it is worth noting that this plant is vulnerable to drought stress, and as such, it is crucial to ensure proper water management when introducing and cultivating it.