Two kinds of experimental results obtained from time-resolved second-harmonic spectra for 1.06 μm laser-produced plasma are presented. At moderate laser intensities (≤2×1014 W/cm2) the results are explained with parametric and electron decay instabilities. Whereas, at high laser intensities (≥6×1014 W/cm2) the Langmuir strong turbulence is used to explain experimental results. In addition to results obtained by Briand et al. [Phys. Fluids B 2, 160 (1990)], a second sequence of collapses is observed.