OPTIMAL LEAF NITROGEN CONTENT OF AN EVERGREEN UNDERSTOREY PLANT IN A TEMPERATE CLIMATE

摘要

In a temperate climate, evergreen species in the understorey are exposed to large seasonal changes in light and temperature. Photosynthetic activity reacts directly to changes in temperature and light. The light utilization (LU) function of the photosynthetic apparatus (electron transport proteins, ATP-synthesis and carbon reduction cycle) is more sensitive to temperature than to light while the reverse holds for the light harvesting function (LH, chlorophyll-protein complexes). Acclimation of the photosynthetic apparatus to changes in either light or temperature by which a balance between the amount of LU and LH components are maintained are well documented (e.g., Berry & Bjorkman 1980, Bjorkman 1981, Evans & Seemann 1989). But acclimation to simultaneous changes in light and temperature has been less studied (e.g., Huner et al 1998), and not at all under natural conditions.