【摘要】 研究了大花组的束花石斛和黄花石斛的光合生理,结果表明,2种石斛叶片的解剖结构为异面叶,气孔仅分布在下表面,具气孔盖,叶脉维管束鞘不含叶绿体,无花环型结构,具C3植物特征.2种石斛的光补偿点(LCP)和光饱和点(LSP)分别为5～10μmol/(m2.s)和850～900μmol/(m2.s),最大光合速率(Pn)约为6μmol/(m2.s);CO2补偿点和饱和点分别为80～90μmol/mol和800μmol/mol;光合作用的最适温度在26～30℃.Pn日变化为双峰型曲线,首峰出现在11:00左右,最大光合速率在5～6μmol/(m2.s),次峰出现在15:00左右,夜间不吸收CO2.PEPCase活性低,RuBPCase和GO酶活性较高.以上结果表明,束花石斛和黄花石斛光合作用碳同化途径属C3植物类型,具有半阴生植物的特点.更多还原

【Abstract】 Photosynthetic physiology of Dendrobium Chrysanthum and Dendrobium dixanthum were studied.Cross-sections of the leaves of 2 Dendrobium species showed that they were bifacial leaves,and the abaxial epidermis had large amount of stomata,which covered by the waxy stomatal cover,the vascular bundles had no chloroplast and no ’Kranz’ structures,and shown C3 plant characteristics.Their light compensation points(LCP) and light saturation points(LSP) were 5~10 μmol/(m2·s1) and 850~900 μmol/(m2·s1),respectively,max photosynthetic rate was around 6 μmol/(m2·s1);the CO2 compensation points(CCP) and the saturation points(CSP) were 80~90 μmol/mol1 and 800 μmol/mol1,respectively,the optimum temperatures of the photosynthesis were in range of 26~30 ℃.The Pn diurnal variations in 2 Dendrobium species were all bimodal curves,with the first peaks ca 5~6 μmol/(m2·s1) and emerging in 11:00,and the second peaks emerging at about 15:00,and no CO2 absorption occurred in night.The two Dendrobium species both had relatively high RuBPCase and GO activities,but very low PEPCase activities.All results suggested that Dendrobium chrysanthum and D.dixanthum were typical semi-shade C3 plants.更多还原