  Properties of light-light mesons are described by the effective Hamiltonian
with spinless quarks derived from QCD. The spectrum is computed by the WKB
method and shown to reproduce the celebrated linear Regge trajectories even for
the lowest levels. The correct string slope of the trajectories naturally
appears in the present approach as the string dynamics is taken into account
properly.
  Similar method is applied to heavy-light mesons and a set of corrections to
the Hamiltonian is taken into account including spin-spin and Tomas spin-orbit
interactions. The numerical results for the spectrum are compared with the
experimental data and with the results of recent lattice calculations.
