Abstract:
Vatica guangxiensis is a national first-class protected wild plant and extremely small
populations wild plant. This paper provides a comparative analysis of the photosynthetic physiological
characteristics and structural features of Vatica guangxiensis seedlings and adult trees. The Li-6400
portable photosynthesis measurement system analyzer and vacuum electron scanning microscope were
utilized to investigate the differences between the photosynthetic capacity and leaf structure of leaves at
different stages of growth and development. The results were as follows: (1) The right-angled hyperbolic
modified model was the best model to fit the light response of Vatica guangxiensis seedlings and adult
plants. (2) The maximum net photosynthetic rate(Pnmax), light saturation point (LSP) and dark respiration
rate (Rd) of adult leaves were significantly higher than those of seedlings, the light compensation point
(LCP) of adult plants was lower than that of seedlings(P<0.05). (3) Chlorophyll a, chlorophyll b,
chlorophyll (a+b) and carotenoids in seedlings were significantly lower than in adult plants(P<0.05). (4) The stomatal long axis, stomatal organ area and stomatal density of adult plants were significantly higher
than those of seedlings; the leaf area and specific leaf weight (SLW) of adult plants were significantly
larger than seedling (P<0.05), and the specific leaf area (SLA) was smaller than seedling. In summary,
Vatica guangxiensis exhibits photosynthetic characteristics of a shade-loving seedling and a sun-loving
adult tree. The seedlings have weak light adaptation ability and light energy utilization, and are unable to
photosynthesize sufficiently to meet their growth needs due to excessive shading by adult trees. This is a
significant reason why seedlings are unable to grow into large trees. Therefore, for insitu conservation of
Vatica guangxiensis, human interference can be used to artificially create ‘windows’ in the tree layer to
provide sufficient light sources. This is conducive to the growth of Vatica guangxiensis seedlings into
large trees and the renewal of the population. On the other hand, for the introductory cultivation of Vatica
guangxiensis, the seedlings need to be appropriately shaded and transplanted to a certain degree of shade.
During the initial cultivation process, it is important to provide appropriate shading for seedlings and
transplant them to an environment with a suitable level of shade.