EN
Corrections to the molecular-field ground-state energies of the Heisenberg model with isotropic biquadratic interactions (spin S=3/2) are calculated in the (1/z)^1-approximation using the diagrammatic technique based on the Wick reduction theorem (z is the number of spins interacting with any given spin). The present results for the antiferri- and antiferromagnetic phases complete the previously obtained data for the antiquadrupolar, ferri- and ferromagnetic phases. From among the boundaries between different ground states only that between the antiferri- and antiferromagnetic phases is shifted with respect to its molecular-field value.