The grain nitrogen content for landraces was 13.5% while it is 12.3% for modern varieties. (5) Landraces were healthier than modern varieties; (6) Arbuscular mycorrhiza fungi wheat root colonisation was 5% higher in landraces (35.2%) than modern varieties (29.4%) in these conditions unfavourable to mycorrhiza due to ploughing. (7) Wheat lodging was 38.5% for landraces while it was around 1% for modern varieties. Intercropping wheat with legumes decreased wheat grain yield by around 25%, but increased wheat grain nitrogen content from 12.7 to 13.8%, independently between landraces and modern varieties. This study provides novel evidence of the interests of diversifying crops, either through intravarietal genetic diversity (the use of landraces) and inter-specific diversity (intercropping of wheat and legumes), for both wheat performance and stability.