Are Hull-less Barley and Lentil a Good Match? Production Performance and Co-Growth Dynamics in a Three-year Mixed Cropping Experiment in Switzerland

Diversifying agroecosystems through crop mixtures has been widely evaluated, demonstrating advantages over conventional sole cropping. In this three-year field experiment in central Switzerland, four lentil ( Lens culinaris ) cultivars were intercropped with three spring hull-less barley ( Hordeum vulgare var. nudum ) cultivars by substituting 25% of the lentil seed density in a replacement design. These mixtures were compared with the corresponding sole cropping systems, including both fertilized (additional nitrogen) and non-fertilized hull-less barley treatments, resulting in 22 total treatments.Throughout the growing seasons, we recorded morphological traits (tiller number and plant height) and phenological stages (BBCH 65 in lentils and BBCH 55 in hull-less barley) to characterize the co-growth dynamics. We then correlated these traits with performance metrics: weed suppression, lodging reduction, total and partial grain yield, land equivalent ratio (LER), net effect (NE), and competitive ratio (CR).Mixed cropping reduced both weed biomass and lodging incidence while increasing total grain production, evidenced by LER > 1 and positive overyielding. In mixed cropping, hull-less barley tiller number and lentil height increased, while lentil phenology remained unchanged. In contrast, hull-less barley exhibited reduced height and delayed heading compared to fertilized sole crops. Mixed cropping combinations with a high tiller count and more balanced height ratios showed the strongest increases in overall yield. Furthermore, pairings of early-flowering lentil cultivars with late-heading hull-less barley resulted in higher total and lentil grain yields, despite slightly lower LER and NE values.Delayed sowing and unstable precipitation reduced the overall system performance, emphasising the advantages of early sowing for both crops.