Enhancing Germination of Dormant Seeds of Downy Brome

We investigated germination enhancement of downy brome (Bromus tectorumL.) seeds (caryopses) recovered from herbicide fallows in degraded big sagebrush (Artemisia tridentataNutt.) communities. Numbers of germinable downy brome seeds were increased most by adding 0.1 mmole potassium nitrate (KNO3) or combinations of 0.1 mmole KNO3and 0.14 mmole gibberellic acid (GA3). Germinability was enhanced in the fall and spring but not in midwinter when dormancy was greatest. Improved downy brome control and better establishment of seeded forage species with a fallow technique in sagebrush-dominated communities look promising if these growth regulators can be effectively applied in the field. Without germination enhancement, many germinable seeds of downy brome are present in litter under shrub canopies at the end of the fallow period. With near-optimal microenvironment under shrub canopies for plant growth, severe competition between downy brome and the seeded forage species can result.