Granite dust application to hemp - variety-specific impacts on growth and cannabinoid production

The hemp industry has grown exponentially with the recent legalization of Cannabis sativa in Canada. With this new market expansion, there is an increased need for hemp plants, particularly for production of cannabinoids. Growing concerns regarding pesticide residues in commodities for human consumption, as well as global demand for fertilizer has increased consumer demand for natural products as alternatives to synthetic agrochemicals and pest management strategies. The objective of this study was to investigate the potential for using different composite granite dusts applied as soil amendments in improving C. sativa growth, and cannabinoid production (specifically, cannabidiol and cannabidiolic acid). We selected three varieties of industrial hemp with low yield production of cannabidiol (Fibranova, CFX-2, and Katani) and one variety with high yield production of cannabidiol (Cherry Blossom). Varieties were planted in potting soil amended with zero, five or ten percent granite dust mixture, and assayed for growth characteristics, and cannabinoid composition. Among tested cannabis varieties, results suggest that improvements to flower growth (> 44% mass) and cannabinoid production (> 2.5 fold or > 145%) from application of granite dust were evident in one variety of fibre hemp, CFX-2. Overall, this work suggests there may be selective benefits to soil applications of granite dust composites to improve hemp propagation, and that degree of improvement to cannabinoid production vary between varieties of hemp.