Physiological And Morphological Acclimation Of Nine Ficus Species Seedlings To Different Growth Irradiance

Light is one of the most important ecological factors which influence plant growth, development, and forest succession. We can learn more about rain forest renewal and succession through studying the responses of different plant species of light demanding characteristics to different irradiances, In this study I explored ecophysiological characteristics under 5 different light levels in nine Ficus keystone species of Xishuangbanna rain forest.Most variables related to plant size, architecture and growth were influenced by irradiance, biomass and species. Six Ficus species could acclimate to high irradiance by improving the ability to absorb water and nutrition, and net acclimation rate (NAR), and could acclimate to low irradiance by increasing light interception and capture.In high irradiance environment, the photo synthetic ability of sun species (F. hispida, F. semicordata, F. racemosa and F. tinctorid) is higher than those of shade species (F. fistulosa, F. cyrtophylla and F. subulatd). But the difference of photosynthesis between sun and shade plant decrease with irradiance decrease. Under high irradiance sun species have higher maximal acclimation rate (AmaxA), nitrogen, phosphate, chlorophyll, and caroteniod content per leaf area (NA, PA, ChlA, and CarA), nitrogen utilization efficiency (NUE), light compensation point (LCP) and dark respiration (RdA), and lower decreasing CO2 compensation point (Г*). While shade species can maintain survival and growth by increasing NA, PA, NUE, CarA, RdA and decreasing ChU under high irradiance environment. Shade and sun species could acclimate to low irradiance environment by the reverse of the above variables.The ecophysiological characteristics of nine Ficus species is the result of their acclimation to growth environment during evolution, and now these determined their distribution in rain forest. Changes of biomass, plant morphology and architecture, photosynthesis capacity, respiration rate in the nine Ficus species were consistent with their successional stage in rain forest.