  The contributions into radiative correction parameters S, T, U from scalar
leptoquark and scalar gluon doublets are investigated in the minimal four color
symmetry model. It is shown that the existence of the relatively light scalar
leptoquarks and scalar gluons (with masses of order of 1 TeV or less) is
consistent with the current experimental data on S, T, U and the more light
particles (with masses below 400 GeV) improve the fit. In particular, the
lightest scalar leptoquarks with masses below 300 GeV are consistent with the
current data on S, T, U at $\chi^2 < 3.1(3.2)$ for $m_H=115(300) GeV$ in
comparison with $\chi^2 = 3.5(5.0)$ in the Standard Model. The lightest scalar
gluon in this case is expected to lie below $ 850(720) GeV.$ The possible
significance of such particles in the t-quark physics at LHC is emphasized and
their effect on the gauge coupling constant unification is briefly discussed.
