Localization phenomena related to the fluctuating band potential profile of the InGaN alloy were investigated via hydrostatic pressure dependent measurements of luminescence of an InGaN quantum structure. We examine the suitability of the hydrostatic pressure coefficient as a tool for evaluation of the degree of localization of recombining carriers in the InGaN alloy. This is done by experimental investigation of the correlation between the pressure coefficient of the luminescence peak and the Stokes shift between luminescence and the absorption edge, which constitutes a measure of the degree of localization of recombining carriers in the InGaN alloy.