Effects of seeding date on grain and biomass yield of intermediate wheatgrass

Intermediate wheatgrass (Thinopyrum intermedium) (IWG) is a perennial grass being domesticated for grain production with potential to provide economic return and ecosystem services across broad geographic range in North America, yet optimum seeding dates biomass yield are unknown. Our objective was determine the effect of late-summer, fall, spring on grain-type IWG population. Trials were conducted at St. Paul Roseau, MN, Kalispell, MT, Salina, KS. Seeding ranged from August June following year. Grain yields highest when seeded earliest late-summer date all environments except Kansas, where September 29 produced greatest yields. Little no seedings first year, substantiating that photoperiod vernalization requirements needed seed head induction. positively correlated cumulative growing degree days (GDD) winter dormancy. A quadratic response observed KS, maximized GDD accumulation reached 912. Accumulation units throughout winter, after also yield. The minimum varied 50 87 sites. Results highlight important associations between thermal late summer; however, other variables affecting induction (e.g., photoperiod, snow cover) require further study.