  A comprehensive phenomenological analysis of experimental data and some
theoretical models is presented here (for mesons) to critically discuss how
Regge trajectory parameters depend on flavor. Through analytic continuation of
physical trajectories (obtained from resonance data) into the space like
region, we derive the suppression factor for heavy flavor production. The case
of our D Regge exchange, both for D and $\Lambda_c$ production, is considered
in some detail. Good agreement with data is reached confirming that indeed the
slopes of heavier flavors decrease. This result suggests that the confinement
potential has a substantial dependence on the quark masses. In a simple
non-relativistic model, constrained to produce linear Regge trajectories, it is
shown that a linear quark mass dependence is required (in the confinement part
of the potential) in order for the slope to decrease in the appropriate way.
