Unfolding the potential of wheat cultivar mixtures: A meta-analysis perspective and identification of knowledge gaps

•Cultivar mixtures have higher yields than the mean of their pure components.•Overyielding increases under high disease pressure.•Under high disease pressures, overyielding increases with the number of mixed varieties.•Combining diverse heights, phenologies and disease resistances induces higher overyielding.•Except for disease control, mechanisms of mixture performance have not been identified.