遮阴对狼尾草光合特征的影响

Effects of Shading on the Photosynthetic Characteristics of Pennisetum alopecuroides

[目的]为狼尾草栽培技术的优化及其在园林中的正确应用提供理论依据。[方法]采用LI-6400XT便携式光合系统分析仪测定0(对照)、25%、50%和75%遮荫处理下狼尾草(Pennisetum alopecuroides)的叶片光合参数,并测定叶片叶绿素含量与比叶重。[结果]全光照狼尾草的光补偿点(LCP)和光饱和点(LSP)分别为37.24和1892.42μmol/m2.s。遮荫25%、50%、75%处理的狼尾草LCP较全光照分别降低了11.39%、29.11%和63.16%,差异显著,而其表观量子效率(AQY)、LSP、最大净光合速率(Pmax)基本没受影响。遮荫25%、50%、75%处理的狼尾草叶绿素a、b及总叶绿素含量分别较对照增加了48.25%、72.22%和53.07%。遮荫75%处理的比叶重较全光照降低了29.50%。[结论]狼尾草能适应一定的弱光环境,但75%遮荫会显著降低其光合效率,影响其正常生长。

[Objective] The aim was to supply theoretical basis for optimizing the cultivation technology of Pennisetum alopecuroides and its correct application in gardens.[Method] The photosynthetic parameters of P.alopecuroides leaves in treatments with shading degree at 0（CK）,25%,50% and 75% were determined by LI-6400XT portable photosynthetic system analyzer and their chlorophyll contents and specific leaf weights were determined.[Result] The light compensation point（LCP） and light saturation point（LSP） of P.alopecuroides under full illumination were 37.24 and 1 892.42 μmol/m2·s resp.Compared with full illumination,the LCPs of treatments with shading degree at 25%,50% and 75% were decreased by 11.39%,29.11% and 63.16% resp.and the difference was significant,but its apparent quantum yield（AQY）,LSP amd maximum net photosynthetic rate（Pmax） were not affected basically.Compared with CK,the contents of chlorophyll a,b and total chlorophyll of treatments with shading degree at 25%,50% and 75% were increased by 48.25%,72.22% and 53.07% resp.Comapred with full illumination,the specific leaf weight of teatment with shading degree at 75% was decreased by 29.50%.[Conclusion] P.alopecuroides could adapt to certain weak-light environment,but the treatment with shading degree at 75% would decrease its photosynthetic efficiency significantly and affect its normal growth.