Optimal Light Regime for the Rare Species Magnolia wufengensis in Northern China

The rare species Magnolia wufengensis, which is adapted to the natural conditions of its native habitat in southern China, has shown poor growth in northern regions. We analyzed the photosynthetic and growth responses of M. wufengensis grown in northern China under three light levels (100%, 70%, and 40% sunlight) during one growing season. Under 70% sunlight, plants had a maximum net photosynthetic rate (P_max), light saturation point (LSP), seedling height, basal diameter, root biomass and stem biomass. With decreasing light level, the dark respiration rate (R_d), light compensation point (LCP), specific leaf weight, leaf thickness and leaf density significantly decreased, and apparent quantum yield (AQY), maximum fluorescence (Fm), variable fluorescence (Fv), Fm/initial fluorescence (Fo), Fv/Fo, Fv/Fm, chlorophyll content, leaf area and petiole angle significantly increased. We concluded that 70% sunlight was the optimum light level for 1-year-old M. wufengensis seedlings grown in northern China. Poor growth responses were observed under full and 40% sunlight, resulting from excessive and insufficient light energy, respectively. For the successful introduction to northern China, microsites at forest edges or gaps should be favored to provide an optimal light environment for M. wufengensis.