  Using the latest most accurate values of post-Newtonian parameters $\gamma$
and $\beta$ obtained by MESSENGER we impose restrictions on the recently
proposed hybrid f(R)-gravity model in its scalar-tensor representation. We show
that the presence of a light scalar field in this theory does not contradict
the experimental data based not only on the $ \gamma $ parameter (as was shown
earlier), but also on all other PPN parameters. The application of
parameterized post-Newtonian formalism to gravitational theories with massive
fields is also discussed.
