  We explore the competiton of doped holes and defects that leads to the loss
of orbital order in vanadate perovskites. In compounds such as La$_{1-{\sf
x}}$Ca$_{\,\sf x}$VO$_3$ spin and orbital order result from super-exchange
interactions described by an extended three-orbital degenerate Hubbard-Hund
model for the vanadium $t_{2g}$ electrons. Long-range Coulomb potentials of
charged Ca$^{2+}$ defects and $e$-$e$ interactions control the emergence of
defect states inside the Mott gap. The quadrupolar components of the Coulomb
fields of doped holes induce anisotropic orbital rotations of degenerate
orbitals. These rotations modify the spin-orbital polaron clouds and compete
with orbital rotations induced by defects. Both mechanisms lead to a mixing of
orbitals, and cause the suppression of the asymmetry of kinetic energy in the
$C$-type magnetic phase. We find that the gradual decline of orbital order with
doping, a characteristic feature of the vanadates, however, has its origin not
predominantly in the charge carriers, but in the off-diagonal couplings of
orbital rotations induced by the charges of the doped ions.
