采用CIRAS-2便携式光和测定仪,选择晴朗天气对蹄叶橐吾、狭苞橐吾、复序橐吾、多毛蹄叶橐吾、合苞橐吾的叶片光合特性参数进行测定,并通过叶子飘新模型对光响应曲线进行拟合,求得各材料的光饱和点(LSP)和光补偿点(LSP),研究材料光合日变化及其耐荫性,结果表明:5种橐吾属植物中,多毛蹄叶橐吾的净光合速率(Pn)和水分利用率(WUE)最高,抗旱性强.蹄叶橐吾和复序橐吾均有较高气孔导度,在蒸腾速率和净光合速率方面,蹄叶橐吾略高于复序橐吾,复序橐吾WUE最低,抗旱性差,在林荫及湿草甸子环境中生长良好,为较强耐荫能力C3植物,出现“光合午休”现象,主要是由气孔限制引起.5种橐吾的耐荫性由强到弱依次为复序橐吾、狭苞囊吾、合苞橐吾、蹄叶橐吾、多毛蹄叶橐吾.%The diurnal variations of photosynthetic rate (Pn) , stomatal conductance (Cond), transpiration rate(Tr), intercellular CO2 ,oncentration (Ci), water using efficiency (WUE), solar radiation (PAR) of five Ligularia were determined by CIRAS~2 portable photosynthetic system, and the light saturation point (LSP) and the light compensation point (LCP) were calculated at the same time. Among the five Ligularia, the P, and WUE of L. Saccha-linensis were the highest. Both L. Fischeri and L. Jaluensis have higher Cond,the Pn and Tr of L. Fischeri were the higher than L. Jaluensis. WUE of L. Jaluensis was lowest with low dry tolerance and good performance at wet site which was a shade tolerance plant of C3 plant characters with appearing noon-rest phenomenon dued to the stomatal factor. Shade tolerance from strong to weak were ranked as follows: L. Jaluensis > L. Intermedia > L. Schmidtii > L. Fischeri > L. Sacchalinensis.
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