  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 current experimental data on S, T, U allow
the scalar leptoquarks and the scalar gluons to be relatively light (with
masses of order of 1 TeV or less), the lightest particles are preferred to lie
below 400 GeV. In particular, the lightest scalar leptoquarks with masses below
300 GeV are shown to be compatible 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.
