  In the framework of the neutrino oscillation scenario, we discuss the
influence of the uncertainty on the efficiency of the neutrino emitting
reactions 1H(p,e+ \nu_e)2H and 7Be(p,\gamma)8B for the neutrino oscillation
parameters. We consider solar models with zero-energy astrophysical S-factors
S_11 and S_17 varied within nuclear physics uncertainties, and we test them by
means of helioseismic data. We then analyse the neutrino mixing parameters and
recoil electron spectra for the presently operating neutrino experiments and we
predict the results which can be obtained from the recoil electron spectra in
SNO and Borexino experiments. We suggest that it should be possible to
determine tight bounds on S_17 from the results of the future neutrino
experiment, in the case of matter-enhanced oscillations of active neutrinos.
