Associations between cannabinoids and growth stages of twelve industrial hemp cultivars grown outdoors in Atlantic Canada

Abstract

Industrial hemp is increasingly grown and harvested for its cannabinoids of pharmaceutical interest. These compounds are generally obtained from plants harvested at maturity but not all cannabinoids are present or abundant during the last stage of hemp development. This study examined intraspecific cannabinoid variability during ontogenic development of hemp to identify growth stages and cultivars that optimize production of specific compounds. The cannabinoid content of twelve commercial industrial hemp (Cannabis sativa L. subsp. sativa) cultivars at three growth stages (i.e., flowering, grain filling and maturity) was determined by high performance liquid chromatography in an experimental field in Cocagne, New Brunswick, Canada. Most cannabinoids in acidic or neutral form were more abundant at maturity. However, cannabigerolic acid, a precursor to all acidic and neutral forms of cannabinoids mentioned in our study, was more abundant during the grain-filling stage. In contrast, cannabichromene was associated with the flowering stage and found in greater abundances in grain cultivars than in dual-purpose cultivars. The cultivar Katani exhibited higher concentrations of most cannabinoids while the cultivars Ferimon, Altair and Anka exhibited higher concentrations of cannabinoid acidic precursors. The current study could help optimize the targeted production of cannabinoids at specific growth stages and to identify the chemical phenotype of different hemp cultivars.