Typesetter to place Table 2 here
Fo : The F o was measured in dark adapted leaves as the initial minimum fluorescence. As compared to the VC, CAx3 and CAx5 plants had ~8% and ~11% higher F o values, but this must be simply due to higher [Chl] in the transgenics (Table 2); there was no difference in the values ofF o/Chl.
Fm : Maximal fluorescence was measured during the first saturation pulse, after dark adaptation (see Material and Methods). The F m values of CAx3 and CAx5 plants are observed to be higher by ~18% and ~25% (Table 2); theF m/Chl values are 6%-9% higher in the transgenics than in the VC.
Fv /Fm : This ratio is an estimate of the maximum potential quantum efficiency of Photosystem II, if all the reaction centers are open.; this is usually the case when dark-adapted samples are used, as was the case in our experiments; this ratio increased only slightly (~4%) in the transgenic plants (Table 2).
Area over the OJIP curve: This area is betweenF o and F m, and is proportional to the size of the pool of the electron acceptors in PSII, mainly the plastoquinone molecules (Malkin and Kok, 1966); we observe it to be higher (19%-22%) in CAx3 and CAx5 than in the VC (Table 2).
Fv/ Fo: This ratio, which is known to reflect the efficiency of the (electron) donor side of PSII, i.e., the activity of the oxygen-evolving (or the water-splitting) complex (Burke, 1990), was higher (11%- 16%) in the transgenics than in the VC (Table 2).
PI, the performance index: The calculated PI (Tsimilli-Michael et al., 2000) was higher (10%- 20%) in the transgenics than in the VC (Table 2).
Non Photochemical quenching (NPQ): NPQ of the excited state of Chl increased with light intensity. At high light intensity (540 μmol photons m-2 s-1), the NPQ in CAx3 and CAx5 transgenic lines is slightly lower (5% - 9%) than in the VC