Third and fourth year biomass yields of Miscanthus x giganteus, switchgrass, big bluestem, and prairie cordgrass in southern Manitoba, Canada: Latitude of origin affects biomass yield among native grasses

Warm season perennial grasses that use C₄ photosynthesis can provide a reliable supply of bioenergy and biomaterials, achieving the greatest annually harvestable biomass of any crop in most temperate regions. Short growing seasons bookended by cold temperatures and snow cover challenge the productivity of C₄ perennial grasses at high latitudes. Cultivars from higher latitudes also often flower and senesce before fully realizing the late summer and fall growing season, compounding the productivity limitations of a shorter growing season. In contrast, cultivars from southern locations planted at higher latitudes may flower later in the growing season, extending their vegetative growth and productivity. At a common field site in southern Manitoba, Canada we compare first-, third-, and fourth-year biomass yields of Miscanthus x giganteus, and cultivars of switchgrass, prairie cordgrass, and big bluestem, spanning latitudes from southern Manitoba to Illinois/Indiana, USA. In addition, we compared spring canopy closure, plant height, and reproductive development during the fourth growing season. Miscanthus x giganteus (M114) and cultivars Sunburst (switchgrass) and Prairie View (big bluestem) consistently achieved ≥10 Mg ha⁻¹ in their third and fourth years, with M114 achieving 13 Mg ha⁻¹ both years. Both prairie cordgrass cultivars (Red River and IL-102) also achieved ≥10 Mg ha⁻¹ the third year, but their yields were halved in the drier fourth growing season. Among native North American grasses, cultivars originating from higher latitudes showed more vigorous spring growth, but flowered earlier, thus reducing their biomass yields compared to cultivars originating further south of our field site.