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

对生长在山毛榉林隙和林下的3种水曲柳(Fagus Crenata)、瑞香枫(Daphniphllum Humile)和红枫(Acer Rufinerve)叶片的光合作用诱导响应进行了现场研究，结果表明，无论是黑暗还是百亩光强，叶片的光子通量密度(Pfd)突然增加到800U和1500 MU·m^-lt；-2&gt；-1；无论是林隙还是林下，在100亩摩尔光子m^~(-2)~(-2)~(-2)、S~(2+)~(-1)和最大同化率(A&lt；~(100&gt)；max~(gt；))的背景区，水曲柳的同化率和气孔导度均最大。达到完全诱导所需的时间取决于背景PPD S和高PFDs。100个摩尔光子m~(-2)~(-2)~(-2)、S~(2+)~(-1)~(-1)的地面PFD诱导期比黑暗中短2~4倍。对于信号故事中的三个物种，当光照从黑暗增加到800时，完全诱导所需的时间比增加到1500mumol光子m_2&gt；-2；S；-1&gt；林下红枫的初始气孔导度(g&lt；s0&gt；)大于林隙，诱导期较短。在两种生境中，水曲柳具有相似的g&lt；s0&gt；和诱导性。胡麻地被林下的诱导期比林隙中的低，诱导期长。这些结果表明，初始气孔导度与光合作用诱导反应密切相关。植物在光照度突然增加之前所经历的光照条件和增加的程度影响光合作用的诱导反应。

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.