  We present a model for the transport of anisotropic turbulence in an
accretion disc. The model uses the Reynolds stress tensor approach in the mean
field approximation. To study the role of convection in a protoplanetary disc,
we combine the turbulence model with a radiative transfer calculation, and also
include convection using the mixing length approximation. We find that the
turbulence generated by convection causes the angular momentum of the accretion
disc to be directed outwards. We also confirm the conclusions of other authors
that turbulent convection is unable to provide the observed disc accretion
rates as well as a heat source sufficient for the convection to be
self-sustaining. The reasons for the latter are the strong anisotropy of the
turbulence together with the low efficiency of the energy transfer from the
background velocity shear to the turbulent stress tensor.
