Abstract: The photosynthetic characteristics of Panicum maximum cv.Reyan No.8 were measured with the LI-6400 portable photosynthesis system on clear days in the first ten days of September 2006.The results showed that the photosynthesis of P. maximum cv.Reyan No.8 presented a single peak curve, no midday depression.The peak appeared at about 13:00 (Pn=26.9 μmol/m²·s), and changed positively with the variations of transpiration rate and stomatal conductance.The light saturation and compensation points of P. maximum cv.Reyan No.8 were about 1700 μmol/m²·s and 46 μmol/m²·s, respectively.The apparent quantum yield, CO₂ saturation point, CO₂ compensation point and carboxylation efficiency were about 0.0535, 600 μmol/mol, 3.49 μmol/mol and 0.1168, respectively.These results indicated that P. maximum cv.Reyan No.8 was a heliophile C₄ type plant with shade-tolerance.

Key words: Panicum maximum cv.Reyan No.8, photosynthetic characteristics, apparent quantum efficiency, carboxylation efficiency, heliophile C₄ plant

摘要： 2006年9月上旬,在晴天用LI-6400便携式光合仪测定热研8号坚尼草的光合特性。结果显示,热研8号坚尼草的光合日变化呈"单峰型",无"午休"现象,13:00时出现峰值(Pn为26.9 μmol/m²·s),变化趋势与蒸腾速率(Tr)、气孔导度(Gs)等因子相同;叶片光饱和点(LSP)约为1 700 μmol/m²·s,光补偿点(LCP)约为46 μmol/m²·s,表观量子效率(AQY)为0.0535,CO₂饱和点(CSP)为600 μmol/mol,CO₂补偿点(CCP)为3.49 μmol/mol,羧化效率(CE)为0.1168。表明热研8号坚尼草是一种耐荫的C₄型阳性植物。

关键词: 热研8号坚尼草, 光合特性, 表观量子效率, 羧化效率, C₄阳性植物