Photosynthetic induction responses to variable light under field conditions three species grown in the gap and understory of Fagus crenata forest.

本文研究了生长在日本山毛榉（Fagus crenata）差距和林下的3种植物（毛毛榉（Fagus crenata）、虎皮楠（Daphniphyllum humile）和红脉槭（Acer rufinerve））叶片对不同光照的光合诱导反应，在黑暗或100 μ moM光子的条件下，光子通量密度（PFD）突然增加到800和1500 <-2><-1>μ moM<-2>光子<-1>。在<100><s100>背景PFD为100 μ mol photons m^ s^时，毛叶杨的同化速率（A_）、气孔导度（g^）<-2><-1>和A_<100>/A_<max>（A_<max>：最大同化速率）在差距和林下均表现出最大值。达到完全诱导所需的时间取决于背景PPD和高PFD。在100 μ mol光子的地面PFD下的诱导期<-2><-1>比在黑暗中短2-4倍。对于三个物种的诱导，当光照从黑暗增加到800 μ mol光子m_s时，完全诱导所需的时间是增加到1500 μ mol光子m_ s时的2-3倍<-2><-1>。红脉槭林下气孔导度<s0>比差距高，诱导期短。在<s0>两种生境中，毛毛豆的g_（？）和g_（？）林<s0>下虎皮楠的g_（1/2）较林窗低，诱导期较差距窗长.这些结果表明，初始气孔导度与光合诱导反应密切相关。植物在光照条件下所经历的突然增加的辐照度和增加的程度影响了光合诱导反应。

Photosynthetic induction responses to variable light were examined in situ for leaves of three species, Fagus crenata, Daphniphyllum humile, and Acer rufinerve, grown in the gap and understory of a Fagus crenata (Japanese beech) forest, with abrupt increases in photon flux density (PFD) to 800 and 1500, mu mol photons m^<-2> s^<-1> from either darkness or 100 mu moM photons m^<-2>s^<-1>. Fagus crenata exhibited the greatest assimilation rate (A_<100>), stomatal conductance (g^<s100>) at the back ground PFD of 100 mu mol photons m^<-2>s^<-1>, and A_<100>/A_<max> (A_<max> : maximum assimilation rate) both in the gap and understory. Time required to achieve full induction depend on both background PPD s and high PFDs. induction period at the ground PFD of 100 mumol photons m_<-2> s_<-1> was 2-4-fold shorter than in darkness. For the three species in the uncierstory, time required to full induction was 2-3-fold Longer as the light was increased from darkness to 800 than to 1500 mumol photons m_<-2>s_<-1>. Acer rufinerve in the understory showed greater initial stomatal conductance (g_<s0>) and shorter induction period than in the gap. Fagus crenata tended to have similar g_<s0> and induction in both habitats. Daphniphyllum humi(e demonstrated lower g_<s0> and a longer induction period in the understory than in the gap. These findings indicate that initial stomatal conductance is closely correlate to the photosynthetic induction response. Light conditions plants experienced before a sudden increase in irradiance and the degree of the increase affected the photosynthetic induction response.