  The interaction correction to the conductivity of 2D hole gas in strained
GaAs/In$_x$Ga$_{1-x}$As/GaAs quantum well structures was studied. It is shown
that the Zeeman splitting, spin relaxation and ballistic contribution should be
taking into account for reliable determination of the Fermi-liquid constant
$F_0^\sigma$. The proper consideration of these effects allows us to describe
both th temperature and magnetic field dependences of the conductivity and find
the value of $F_0^\sigma$.
