Accumulation of cannabidiol during the ontogenesis of industrial hemp

Abstract

Purpose. To find out the specifics of cannabidiol and other cannabinoid compounds accumulation during the ontogenesis of industrial monoecious hemp (i); to determine the optimal phenological stage of harvesting for the purpose of obtaining cannabidiol for pharmaceutical purposes (ii); to find out the prospects of using hemp for the needs of pharmaceutical industry (iii).Methods. Field, labo­ratory (thin-layer chromatography), statistics (correlation and regression analysis).Results. The results of three-year research on the dynamics of biomass accumulation in the ontogenesis of hemp plants of the ‘Hliana’, ‘USO 31’ and ‘Zolotoniski 15’ varieties are presented. The manifestation of the content of cannabidiol, tetrahydrocannabinol and cannabinol is given not in terms of their maximum content (using the analysis of apical parts of plants or female flo­wers) but using a weighted average sample of the vegetative mass from all live leaves and inflorescences.Conclusions. The presence and intensity of certain cannabinoid compound accumulation are the hereditary signs. A small number of cannabinoids in hemp can be identified already at early stages of development, in particular at the 1–3 true leaf pairs stage. On the basis of theoretical calculations and in accordance with the described research methodology, it was found that the optimal period for harvesting biomass of pharmaceutical hemp with subsequent release of cannabidiol is the period from full flowering to the stage of biological maturity. Certain families of the ‘Hliana’ variety involved into selection for increasing cannabidiol content can produce about 5.808 g/m2 of the active substance. The families of variety ‘USO 31’ can produce 1.528 g/m2 and the ‘Zolotoniski 15’ 1.563 g/m2 of the active substance. Inflorescences of hemp contain much more cannabinoid compounds compared to leaves; however, taken into account their shares in the total biomass of plants, it can be argued that inflorescences and leaves are equally suitable for use as a source of cannabidiol. The use of industrial hemp in the pharmaceutical industry is promising but on the assumption of the target breeding