  Experimental data at RHIC and SPS energies suggest a systematic correlation
between yield ratio $\bar{p}/p$ and $K^{-}/K^{+}$, which reveal some
universality of hadron production in relativistic heavy ion collisions. We
propose an explanation based on the quark combination mechanism in which the
production asymmetry between baryons and antibaryons is focused on especially.
We start from the basic ideas of quark combination to carry out a general
analysis of the properties of the global production of baryons and mesons and
obtain the yields of baryons, antibaryons and mesons as functions of the number
of constituent quarks and antiquarks just before hadronization. In particular,
we study effects of quark-antiquark asymmetry on the ratio of (anti-)baryons to
mesons and that of antibaryons to baryons. We use these formula to well explain
the data of $\bar{p}/p$ and $K^{-}/K^{+}$ at different of collision energies
and rapidities and suggest further measurements at moderate RHIC energies in
the mid-forward rapidity regions to make the decisive test of this
universality.
