Left panels: the comparison between the star formation rate determined using a SED fitting technique and the one determined using the Hα emission. For the SED fitting determination, all galaxies are assumed to be 13 Gyr old. Three different parametric star formation histories are assumed: exponential (upper panel), double exponential (middle), and delayed (lower). Green symbols indicate those objects where the normalised , black symbols those with . Filled symbols are for HI-normal galaxies, empty symbols for HI-deficient objects (HI - def ≤ 0.4). The black solid line shows the 1:1 relation, the black dotted line the bisector fit (and σ its dispersion) determined using galaxies with . Right panels: relationship between the SFR_SED/SFR_Hα ratio and the HI-deficiency parameter.