Effect of drought stress on photosynthetic properties of Illicium lanceolatum

Understanding the relationship between plants and water has been a major subject of research in plant physiological ecology. Illicium lanceolatum is a conventional medicinal plant species in China. No study has been done to understand the mechanism of how this species responds to water and light conditions. One year old seedlings of four ecotypes were transplanted into pots and drought stress was applied by withholding water for different time- periods. Results show that photosynthetic parameters differ significantly in these ecotypes during the drought stress and the recovery period. As the drought stress progressed, the light saturation points (LSP) and the light compensation point (LCP) declined. The maximum photosynthetic ratio (Pmax) increases initially and then decreases rapidly during the drought treatment period. The apparent photon quantum yield (AQY) increases as drought stress progressed. Significant changes in LSP, LCP, AQY and Pmax, occur between the recovery period and the pre-drought treatment condition, but the level of relative difference is affected by the ecotypes. During the recovery period, the LSP of WN, KH and LA ecotypes is higher than the pre-drought treatment condition, the LCP also recovers rapidly, and AQY also remains at a high level. These results indicate that the four ecotypes are different in the capacity to adapt to light intensity and water stress. The photosynthetic response curve also changes in response to drought stress. Therefore, I. lanceolatum requires a growing environment to provide adequate soil moisture as well as light intensity.