  In this paper, we obtain asymptotic formulas for eigenvalues and
eigenfunctions of the operator generated by a system of ordinary differential
equations with summable coefficients and the quasiperiodic boundary conditions.
Using these asymptotic formulas, we find conditions on the coefficients for
which the root functions of this operator form a Riesz basis. Then we obtain
the uniformly convergent spectral expansion of the differential operators with
the periodic matrix coefficients
