Various configurations of three-wave parametric interactions are reported at the picosecond time scale, in 3-methyl-4-nitropyridine-1-oxide (POM) single crystals. Wavelength dispersion of phase-matched second-harmonic generation orientation is experimentally established within the 0.8-2 \mu m range using as fundamental input the idler and signal emissions of a picosecond LiIO 3 parametric emitter. Efficient parametric amplification is demonstrated: at degeneracy a gain of 103is measured for a pump intensity of 130 MW . cm-2at 0.53 μm and an input signal of 5 kW . cm-2at 1.06 μm. Single pass parametric emission is achieved, for the first time in an organic crystal, yielding 200 kW . cm-2at 1.06 μm, using the frequency-doubled output of a passively mode-locked YAG system. Both dispersion and interaction length dependence of the experimental gain are accounted for.