Based on the Chen--M\"oller--Sauvaget formula, we apply the theory of
integrable systems to derive three equations for the generating series of the
Masur--Veech volumes VolQg,n associated with the
principal strata of the moduli spaces of quadratic differentials, and propose
refinements of the conjectural formulas given in [12,4] for the large genus
asymptotics of VolQg,n and of the associated area
Siegel--Veech constants.Comment: 17 page