水分胁迫下毛竹幼苗光合及叶绿素荧光特性的响应

为分析水分胁迫对毛竹幼苗光合、荧光特性及水分利用效率的影响，以1年生毛竹为试验材料，采用气体交换和叶绿素荧光成像技术，研究不同水分亏缺条件下毛竹幼苗叶片光合生理参数的变化。研究表明:①随着胁迫程度的加深，光系统PSⅡ反应中心活性减弱与光合速率降低一致，气孔限制及PSⅡ反应中心可逆失活或破坏是其净光合速率（Pn）降低的主要原因；②从无胁迫（NS）处理至重度胁迫（HS）处理，光饱和点（LSP）下降20.45%，最大净光合速率(Pnmax)下降67.22%、PSⅡ最大光化学量子产量（Fv/Fm）减少22.46%，有效荧光产量减少45.60%；③低度胁迫（LS）处理水分利用效率较NS处理提高17.81%，光化学淬灭系数（qP）和非光化学淬灭系数（qN）先降低后升高；④初始荧光(Fo)、最大荧光(Fm)、Fv/Fm变异系数均随胁迫处理程度加深而增大，Fo变异区间为18.182%～26.404%，Fm为16.321%～24.899%，Fv/Fm 为1.291%～33.932%。 

Photosynthetic and chlorophyll fluorescent responses of Phyllostachys pubescens seedlings to water deficiency stress

With leaves of 1-year-old Phyllostachys pubescens seedlings under water deficiency to different extents, changes in photosynthetic parameters were studied using a gas exchange photosynthesis system, Mini-Pam chlorophyll fluorometer and fluorescence imaging in order to understand the effects of water deficiency stress on photosynthetic and chlorophyll fluorescent characteristics and water use efficiency. Results showed that: 1) with an increase of water deficiency stress, decrease in activity of the photosystem Ⅱ (PSⅡ) central reaction was consistent with the decreasing photosynthetic rate, which mainly resulted from stomatie limitation and inactivation or damage to PSII central reaction reversibility; 2) from non-stress (NS) to heavy stress (HS), light saturation points(LSP), the maximum net photosynthetic rate, F_v/F_m and effective quantum yield decreased by 20.45 %, 67.22 %, 22.46 % and 45.60 %, respectively; 3) water use efficiency (WUE) increased by 17.81% under light stress than under NS, while photochemical quenching coefficient (q_p) and non-photochemical quenching coefficient (q_N)decreased first, followed by an increase then; and 4) variation coefficients of F_o,F_mand F_v/F_m increased with the increased water deficiency stress, the values of which ranged from 18.182% to 26.404%, from 16.321% to 24.899% and from 1.291% to 33.932%, respectively.