Biomass, stalk, grain, and root crown characteristics of silage maize hybrids interseeded with alfalfa

Abstract Adoption of alfalfa ( Medicago sativa L.)–maize ( Zea mays L.) intercropping in cold temperate regions is limited in part by reduced forage mass of silage maize. A 2‐year trial in Wisconsin quantified the impact of interseeding alfalfa immediately after maize planting on biomass, stalk, grain, and root characteristics of 10 hybrids no‐till planted in May. Soil moisture and plant traits were assessed during crop growth. Maize was harvested in September and then root crowns were dug and phenotyped. Interseeding reduced forage biomass by 18% and 27% in hybrid groups classified as having a small or large reduction in biomass production in response to interseeding, and by 16% in 2021 and 29% in 2022 relative to solo‐seeded maize. Biomass of solo‐seeded maize was not affected by hybrid group or year. Interseeding with alfalfa reduced dry matter concentration, N status, and development of stalks, grain, and roots of maize. Differences between cropping systems for plant traits were greater in 2022 when dry soil restricted growth of interseeded maize to a greater degree than solo‐seeded maize. When interseeded, hybrids in the small biomass reduction group had greater kernel counts, plant height, light absorption, early season N status, and suffered less depression in dry matter concentration at harvest than hybrids in the large biomass reduction group. Our results suggest hybrids can differ in their suitability for intercropping with alfalfa.