## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline  & **F\({}_{\text{v}}\)/F\({}_{\text{m}}\) (r.u.)** & **\(\Phi\)PSII (r.u.)** & **NPQ (r.u.)** & **ETR (\(\mu\)mol electrons m\({}^{-2}\) s\({}^{-1}\))** \\ \hline N.I.C. & 0.8086 \(\pm\) 0.0019 a & 0.488 \(\pm\) 0.004 a & 0.276 \(\pm\) 0.015 a & 11.29 \(\pm\) 0.02 a \\ N.I.S. & 0.8049 \(\pm\) 0.0069 a & 0.440 \(\pm\) 0.004 b & 0.306 \(\pm\) 0.009 a & 10.45 \(\pm\) 0.11 b \\ A.C. & 0.8150 \(\pm\) 0.0015 a & 0.499 \(\pm\) 0.004 a & 0.188 \(\pm\) 0.009 a  & 11.62 \(\pm\) 0.15 a \\ A.S. & 0.8198 \(\pm\) 0.0001 b  & 0.488 \(\pm\) 0.004 a  & 0.488 \(\pm\) 0.004 a  & 0.272 \(\pm\) 0.012 b  & 11.30 \(\pm\) 0.17 a  \\ B.C. & 0.8195 \(\pm\) 0.0010 a & 0.482 \(\pm\) 0.005 a & 0.172 \(\pm\) 0.006 a  & 11.17 \(\pm\) 0.08 a \\ B.S. & 0.8241 \(\pm\) 0.0009 b  & 0.503 \(\pm\) 0.008 a  & 0.228 \(\pm\) 0.020 b  & 11.60 \(\pm\) 0.21 a  \\ G.C. & 0.8098 \(\pm\) 0.0029 a & 0.481 \(\pm\) 0.016 a & 0.248 \(\pm\) 0.016 a & 10.92 \(\pm\) 0.60 a  \\ G.S. & 0.8182 \(\pm\) 0.0017 a  & 0.488 \(\pm\) 0.003 a  & 0.252 \(\pm\) 0.016 a & 11.35 \(\pm\) 0.29 a  \\ H.C. & 0.7979 \(\pm\) 0.0080 a & 0.467 \(\pm\) 0.003 a & 0.208 \(\pm\) 0.010 a  & 10.87 \(\pm\) 0.07 a  \\ H.S. & 0.8186 \(\pm\) 0.0014 b  & 0.469 \(\pm\) 0.004 a  & 0.345 \(\pm\) 0.028 b & 10.87 \(\pm\) 0.06 a  \\ U. C & 0.8160 \(\pm\) 0.0023 a & 0.511 \(\pm\) 0.001 a & 0.164 \(\pm\) 0.010 a  & 11.41 \(\pm\) 0.08 a  \\ U. S & 0.8200 \(\pm\) 0.0016 a  & 0.454 \(\pm\) 0.009 b & 0.239 \(\pm\) 0.031 a  & 10.85 \(\pm\) 0.26 a  \\ \hline \end{tabular}
\end{table} 
Table 4: Chlorophyll fluorescence parameters, maximal quantum efficiency (F\({}_{\text{v}}\)/F\({}_{\text{m}}\)) measured in dark-adapted leaves and quantum efficiency of PSII photochemistry (\(\Phi\)PSII), non-photochemical quenching (NPQ), and electron transport rate (ETR) measured at steady state with actinic light illumination of 55 \(\mu\)mol photons m\({}^{-2}\) s\({}^{-1}\) in _B. napus_ cv. SY Saveo plants grown for 30 days on non-saline soil (C) or saline soil (S). Plants were inoculated with plant growth-promoting bacteria (A = _A. brasilense_, B = _B. anphifaria_, G = _A. globiformis_, H = _H. seropedica_, U = _Pseudomonas_ sp. UW4) or not (N.I. = non inoculated). Different letters mean significant differences within the same bacterial treatment. Significant differences between inoculated or non-inoculated plants grown at the same soil conditions are marked as * (_p_ < 0.05) (_n_ = 4). inoculated and stressed plants, the higher water content could depend on the production of osmolytes, such as proline and trehalose, resulting in decreased membrane damage. In fact, plants able to accumulate proline and trehalose are better able to resist osmotic stress caused by salinity [16; 18; 53]. In the experiments reported here, canola inoculated with _A. globiformis_ produced a very large amount of proline when grown in saline soils (Table 2), confirming the data obtained in vitro [20]. The other tested strains did not induce the overproduction of proline. Strain _Pseudomonas_ sp. was previously shown to produce trehalose [18]. It is likely that the higher water content detected in inoculated and salt-exposed plants is related to a protective action of bacteria on cell membranes, as detected by a significantly lower degree of MII (Figure 3), in agreement with the data of [PERSON] et al. (2021) [20]. Such decreased membrane damage of inoculated plants can also be due to a more efficient antioxidant response, that counteracts the overproduction of reactive oxygen species (ROS) caused by salinity. ROS can cause the depolarization of cell membranes, destabilizing the membrane itself and eventually leading to cell death via cytoplasmic Ca\({}^{2+}\) concentration increase [54]. However, plants with high antioxidant activity, either constitutive or induced, can withstand oxidative stress [55]. This can be achieved through the production of a plethora of antioxidant molecules, such as phenols and carotenoids [56], or by enzymatic activity [16].