  A sharp peak in the $K^+/\pi^+$ ratio in relativistic heavy-ion collision is
discussed in the framework of the SU(3) Polyakov-loop extended NJL model with
vector interaction. In the model, the $K^+/\pi^+$ ratio was calculated along
the chiral phase transition line for different values of the vector coupling
$g_V$. We showed that the value of the vector coupling had no significant
effect on the $K^+/\pi^+$ behaviour.
