Registration of ‘Empire’ big bluestem

Abstract ‘Empire’ (Reg. no. CV‐18, PI 700112) big bluestem ( Andropogon gerardii Vitman) is a 54‐clone synthetic selected for high biomass yield. Empire is broadly adapted to USDA hardiness zones 3–7, ranging from the Great Plains to the eastern United States. Although Empire was developed as a high‐biomass cultivar for use in establishing perennial biomass production for conversion to bioenergy, it has a heading date similar to many other big bluestem cultivars, suggesting that it could be used as a forage crop as well for either hay or pasture production. Under an optimal single‐harvest biomass production management, Empire ranked 1st in biomass yield for 8 of 12 locations in multiple‐year trials averaged over a total of 40 environments (location‐trial‐years). Biomass yield of Empire, averaged over 12 locations, was 30% higher than ‘Goldmine’, 46% higher than ‘Champ’, and 52% higher than ‘Bonanza’. Ground cover of Empire was slightly higher than for most check cultivars, averaging 80% across all 12 locations. Empire is broadly adapted to USDA hardiness zones 3–6, extending from the Great Plains to the eastern United States and was released to the public by the USDA Agricultural Research Service in 2021.