Deuteron NMR experiments on dideuterium dissolved in the nematic liquid-crystal solvents 7CB, CCH7, MBBA and PCH7 are reported as a function of temperature. The results are analysed in terms of the average solvent electric field gradient anisotropy (efg) felt by D-2 which is positive with respect to the director in 7CB, CCH7 and PCH7 and negative in MBBA. The order parameter of D-2 is to a large extent rationalized in terms of the interaction between this solvent efg and the solute D-2 molecular quadrupole moment, and its sign is the same as that of the efg. (c) 2006 Elsevier B.V. All rights reserved.