Silphium Integrifolium: An Alternative Perennial Oilseed Crop and Its Agronomic Potential.

Silphium integrifolium (Silphium) is a perennial oilseed crop being domesticated for use as an alternative to annual oilseeds such as sunflower (Helianthus annuus). Silphium is drought tolerant, sequesters carbon, and is a source of native pollinator forage. Research on Silphium at the University of Minnesota includes three intersecting components. First, the development of genomic resources for the plant, including a reference genome and examination of existing variation for traits and phenotypes along its native range. Second, the use of these genomic resources to develop breeding lines and determine important domestication traits to select for in Silphium. The final component includes growing Silphium under various agronomic conditions, including variable planting densities, nitrogen rates, and seeding dates, to determine the optimum growing conditions for maximizing biomass and seed production of the plant. In 2016, we found that 58,319 plants ha^-1 and 180 kg N ha^-1 produced the greatest biomass and seed yields. In comparing fall and spring planting dates, planting Silphium in September of the year prior to the first seed harvest resulted in the greatest biomass and seed yields the following year. Ongoing field studies will inform future breeding and agronomic research to maximize productivity of this potential perennial oilseed.