The model couples stomatal conductance (gs) and net photosynthetic rate (PN) describing not only part of the curve up to and including saturation irradiance (Imax), but also the range above the saturation irradiance. Maximum stomatal conductance (gsmax) and Imax can be calculated by the coupled model. For winter wheat (Triticum aestivum) the fitted results showed that maximum PN
(Pmax) at 600 µmol mol-1 was more than at 350 µmol mol-1 under the same leaf temperature, which can not be explained by the stomatal closure at high CO2 concentration because gsmax at 600 µmol mol-1 was less than at 350 µmol mol-1. The irradiance-response curves for winter wheat had similar tendency, e.g. at 25 °C and 350 µmol mol-1 both PN and gs almost synchronously reached the maximum values at about 1 600 µmol m-2 s-1. At 25 °C and 600 µmol mol-1 the Imax corresponding to Pmax and
gsmax was 2 080 and 1 575 µmol m-2 s-1, respectively. and Z.-P. Ye, Q. Yu.
Simultaneous measurements of leaf gas exchange and chlorophyll fluorescence for Koelreuteria paniculata Laxm. at 380 ± 5.6 and 600 ± 8.5 μmol mol-1 were conducted, and the photosynthetic electron flow via photosystem II (PSII) to photosynthesis, photorespiration, and other electron-consuming processes were calculated. The results showed that the photosynthetic electron flow associated with carboxylation (Jc), oxygenation (Jo), and other
electron-consuming processes (Jr) were 72.7, 45.7, and 29.4 μmol(e-) m-2 s-1 at 380 μmol mol-1, respectively; and 86.1, 35.3, and 48.2 μmol(e-) m-2 s-1 at 600 μmol mol-1, respectively. Our results revealed that other aspects associated with electronconsuming processes, except for photosynthesis and respiration, were neither negligible nor constant under photorespiratory conditions. Using maximum net photosynthetic rate (Pmax), day respiration (R), photorespiration rate (Rl), and maximum electron flow via PSII
(Jmax), the use efficiency of electrons via PSII at saturation irradiance to fix CO2 was calculated. The calculated results showed that the use efficiency of electrons via PSII to fix CO2 at 600 μmol mol-1 was almost as effective as that at 380 μmol mol-1, even though more electrons passed through PSII at 600 μmol mol-1 than at 380 μmol mol-1., Z. P. Ye, Q. Yu, H. J. Kang., and Obsahuje bibliografii