Comparison on the photosynthetic characteristics between Tilia miqueliana and T.cordata at seedling stage

The photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO2 concentration of the 2-year-old Tilia miqueliana and T.cordata were measured under field condition on sunlight day of August using Li-6400 portable photosynthesis system. The photosynthetic characteristics of the two species were compared. The results showed the rate of foliar photosynthesis, the rate of foliar respiration, the rate of foliar transpiration and stomatal conductance changed in a double-peak curve. However, the intercellular CO2 concentration changed in a single-vale curve. The light compensation points (LCP) of the two species were 36.2 μmol/(m2·s) and 22.8 μmol/(m2·s) respectively. The light saturation points (LSP) were respectively 1 384.8 μmol/(m2·s) and 1 216.5 μmol/(m2·s). The CO2 compensation points (CCP) were respectively 76.4 μmol/mol and 80.9 μmol/mol. The CO2 saturation points (CSP) were 1 872.5 μmol/mol and 1 655 μmol/mol. With regard to the net photosynthesis of these two species, the net photosynthesis of T.miqueliana was higher than that of T.cordata.