林下人参叶片光合日变化的初步研究

Research on Diurnal Change of Photosynthesis of Ginseng Leaf under Forest

采用CI-310便携式光合作用测定系统,研究了人工落叶松(Larix dahuric)林下随机选取的5个试验单位林下人参净光合速率(Pn)日变化与影响因子的关系。结果表明:研究地点林下人参Pn最大为1.6μmol/(m2.s),绝大多数<1μmol/(m2.s),早晚甚至出现负值,明显低于荫棚和人工光照条件下的Pn值;光合有效辐射(PAR)是影响林下参Pn的主要因素,Pn与PAR存在显著的对数关系,r2≥0.808;温度<23℃时,气温(Ta)与Pn呈显著正相关(r≥0.887);胞间CO2浓度(Ci)与Pn呈显著负相关(│r│≥0.737);湿度(RH)与Pn无显著相关性(│r│≤0.419);Pn不受气孔导度(Gs)限制,二者无显著相关性,而蒸腾速率(Tr)对Pn日变化有显著影响(r≥0.707)。

The relationships between influencing factors and diurnal change of net photosynthesis rate （Pn） in 5 random experimental units belonging to the man-made Larix dahuric forest were investigated using CI- 310 portable photosynthesis system. Five conclusions were drawn. The maximum of Pn was 1.6 μmol/（m^2.s）, most Pn was under 1 μmol/（m^2·s）, and negative value appeared in the morning and in the evening; Photosynthetically available radiation （PAR） was the main influencing factor on Pn and logarithmic relation between Pn and PAR was significant, r2 ≥ 0. 808 ; Under 23 ℃, positive correlation between air temperature and Pn was significant （ r ≥ 0. 887） ; Negative correlation between intercellular CO2 concentration （Ci） and Pn was significant （ ｜ r ｜≥0.737） ; Negative correlation between relative humidity and Pn was not significant （ ｜ r ｜≤0.419） ; Stomatal conductance （Gs）did noy limit Pn and transpiration rate （Tr） affected it significantly （ r ≥ 0. 707）.