We used three indicators of massive star formation : H _ { \alpha } , FIR and non-thermal radio luminosities , to compare estimations of Star Formation Rate ( SFR ) for the sample of 34 spiral galaxies .
To adjust SFR values , obtained from different indicators , we considered the slope \alpha and/or upper mass limit M _ { up } of Initial Mass Function ( IMF ) as free parameters .
The best agreement between these indicators reaches for M _ { up } \approx 60 - 100 ~ { } M _ { \odot } and \alpha \approx - 3.1 in the high mass end of IMF ( M > 10 ~ { } M _ { \odot } ) .
Parallel with SFR we also estimated FIR excess X _ { FIR } defined as a fraction of the observed FIR which is not related to young massive stars directly . X _ { FIR } is found to be well correlated with types of spiral galaxies and their colors ( B-V ) : the redder a galaxy the higher is its FIR excess .
We conclude that for any parameters of IMF the observed FIR flux of early type spiral galaxies needs the additional source of energy but the massive star radiation .