Abstract:

【Objective】 The growth adaptability of Rhododendron moulmainense in different environments in Shenzhen urban parks was studied to provide a reference for its introduction into urban areas as an ornamental tree species. 【Method】 Ten-year-old R. moulmainense with the same growth statuses, and three planting environments, including waterfront, highland and flatland, were selected in Shenzhen Xiangmi Park. These trees were planted under two irradiance environments, such as half-light and full light, and divided into six experimental plots. The trees flowering rate, growth rate, chlorophyll content, changes of light response curves and diurnal changes of photosynthetic characteristics were determined. 【Result】 (1) Different planting environments had different effects on the morphology and growth of R. moulmainense. The number of flower buds, thickness of new shoots, volume of new shoots and number of new shoots of R. moulmainense in the waterfront half-light plot were significantly higher than those in other test plots (P < 0.05). (2) The content of the chlorophyll a(Chla), chlorophyll b(Chlb) and total chlorophyll(Chlt) in the leaves of R. moulmainense on the flatland-full light plot were significantly higher than those on other test plots, while the Chla, Chlb and Chlt in the flatland half-light plot showed the lowest values. The carotenoid content(Car), Chl a/Chl b(mass ratio, the same below), and Chlt/Car in the highland half-light plot were significantly higher than those on other plots. (3) The maximum net photosynthetic rate(P_n,max), light compensation point(LCP), and light saturation point(LSP) of leaves in the waterfront full-light plot were higher than those on other test plots, the apparent quantum efficiency(AQY) of highland half-light was the highest, and the dark respiration rate(Rd) of leaves in flatland half-light was the highest.【Conclusion】 The chlorophyll content of R. moulmainense will decrease when the soil water content is high or the drainage is not smooth. The plant height and the number of flower buds and new shoots decreased when the light intensity was too high. On the contrary, the growth of new shoots and the formation of flower buds of R. moulmainense were promoted when the light intensity in the environment was weakened, indicating that the soil environment with appropriate shading and water permeability should be considered when planting R. moulmainense in urban parks.

Key words: Rhododendron moulmainense, light, soil water content, photosynthetic characteristics, urban park