For the agroecological transition, intra-plot diversification is a major agroecological lever, and we focused here on varietal mixtures. For wheat, such mixed stands are known to provide a slightly higher yield (overyielding) than the mean of their pure stands but with a large variance (Borg et al, 2018). However, little is known about the underlying genetic determinism of overyielding. We mobilized here a quantitative genetics framework that takes into account not only the effects of genes of a genotype on its own phenotype, the ”direct” genetic effects, DGEs, but also the effects of genes of the other genotypes with which it is mixed, the so-called ”indirect” genetic effects, IGEs (Bijma, 2014).