Industrial Hemp (Cannabis sativa L.) Germination Temperatures and Herbicide Tolerance Screening

Industrial hemp (Cannabis sativa L.) has a long history of human use. Early in the 20th century, some predicted hemp would be the first billion dollar crop given its multiple industrial applications. Government policy that restricted, then prohibited, hemp's use in the U.S. prevented that from happening. A reawakening to the versatility and usefulness of hemp for products ranging from engineering fibers and textiles to food and health products has developed over the last 30 years. Hemp-based products are thriving on the market for public demand. In Virginia, passage of legislation in 2017 made hemp a legal cash crop. Appropriate management decisions rely on information available from researchers. However, very few data on hemp production are available for this region. Hemp varieties may differ in part due to the broad range of latitude associated with their source of origin (e.g., from Italy to Finland in Europe) and thus the plant's differential responses to light and temperature regimes. Thus, a factor such as varietal response to soil temperature at germination could be an important variable for successful establishment, which is critical to crop productivity. Stand establishment, in turn, may be affected by factors such as germination temperature, which has implications for planting date.

Along with establishment, few data have been published regarding hemp's tolerance to different herbicides. To date, the only published studies from the Southern region of the United States regarding hemp production in response to herbicide treatments were conducted in Kentucky. Generating basic information on hemp response to temperature for germination and tolerance to herbicides will be important step for developing a suite of useful agronomic practices that support the incorporation of hemp into Virginia cropping systems. The hemp industry's development in Virginia is still in its early stages, and the research described here focused on questions related to germination temperature and herbicide tolerance will help to improve our understanding of and determine suitable agronomic practices for the crop We thus designed experiments to test the following null hypotheses: Industrial hemp will not differ in germination response to temperatures, regardless of source of origin. Industrial hemp will not differ in measures of visible injury, yield, and growth in response to preemergent or postemergent herbicide treatments.