Aims. Intercropping cereals and grain legumes has the potential to increase grain yield in comparison to the respective sole crops, but little is known about mixture effects at the early crop developmental stage. In cereal legume mixtures, the cereal is usually the dominating partner. We aimed to find out when domination starts, which factors may enhance early domination, and if there is a legacy effect of early domination on later growth stages. Methods. We set up field trials at a low input conventional site in 2020 and an organic site in 2020 and 2021. Treatments included all possible monocultures and 1:1 mixtures of twelve spring wheat (SW) entries, and two faba bean (FB) cultivars. All combinations were each sown in two sowing densities. To measure the effect of the mixture on early crop development, we counted crop emergence (plant m− 2) at ~ 23 days after sowing (DAS) and crop biomass dry matter at ~ 52 and ~ 82 DAS. Results. We found positive mixture effects on SW emergence at the conventional site and on SW and FB emergence at the organic site in 2021. SW was the dominating partner in all three environments; SW domination, without suppressing FB, was already noticed at emergence at the conventional site. There, a small head start of SW at emergence favored dominance at later growth stages and lead to superiority over FB in terms of plant biomass. Conclusions. Understanding early dominancy in intercropping may help in managing competition in mixture to enhance complementarity and improve total productivity.

Aims Intercropping cereals and grain legumes has the potential to increase grain yield in comparison to the respective sole crops, but little is known about mixture effects at the early crop developmental stage. In cereal legume mixtures, the cereal is usually the dominating partner. We aimed to find out when domination starts, which factors may enhance early domination, and if there is a legacy effect of early domination on later growth stages. Methods We set up field trials at a low input conventional site in 2020 and an organic site in 2020 and 2021. Treatments included all possible monocultures and 1:1 mixtures of twelve spring wheat (SW) entries, and two faba bean (FB) cultivars. All combinations were each sown in two sowing densities. To measure the effect of the mixture on early crop development, we counted crop emergence (plant m-2) at ~ 23 days after sowing (DAS) and crop biomass dry matter at ~ 52 and ~ 82 DAS. Results We found positive mixture effects on SW emergence at the conventional site and on SW and FB emergence at the organic site in 2021. Spring wheat was the dominating partner in all three environments; SW domination, without suppressing FB, was already noticed at emergence at the conventional site. There, a small head start of SW at emergence favored dominance at later growth stages and lead to superiority over FB in terms of plant biomass. Conclusions Understanding early dominancy as observed here may help managing competition in mixture to enhance complementarity and improve productivity.