Abstract

In this study, the photosynthetic properties and CO₂ conductance of four-year old plants of Illicium lanceolatum were measured under three different light conditions (full light, half shadow and shadow) treatments. The results show that during the peak growth season, compared to those under full light, plants growing under half shadow light condition had the highest net photosynthetic rate (P_n), water usage efficiency and higher solar energy utilization efficiency (SUE), these plants had the lowest transpiration ratio (T_r) which was the strategy for achieving high photosynthesis and water utilization efficiency. Partial shading has improved SUE of plants. For plants growing under all of three light conditions, the light saturation point (LSP) increased initially then declined in response to increasing light intensity. Light compensation point (LCP) declined when plants were growing under shaded condition with less amount of light. The daily maximum value of net photosynthetic rate (P_max) and the apparent quantum yield (AQY) decreased in the order of half shadow>shadow>full light. There are significant differences (p ≤ 0.05) among the three light conditions. Plants growing under half shadow had the highest light utilization efficiency. Results from this study indicate that half shadow light condition is the most suitable light condition for I. lanceolatum. The partial shade environment promoted rapid growth and accumulation of biomass of the species. This study provided the scientific bases for domestication and cultivation of shikimic acid rich plants.

Key words: Illicium lanceolatum, light environment, photosynthetic properties.