S06 - Session P8 - Dynamic of the nutrient uptake by drug-type Cannabis sativa L. under different N concentrations during the flowering phase of plants cultivated in vertical aeroponic growing system

Authors: Martine Dorais *, Camille Leblanc, Thi Thuy An Nguyen, Annie Brégard

Drug-type Cannabis sativa L. is a fast-growing industry following its legalization in Canada in 2018. However, the lack of scientific agronomic knowledge about cannabis cultivation is one of the main challenges for the growers. To better understand the mineral nutrition of drug-type cannabis, we studied the impact of N on plant growth development, plant nutrient uptake of N, P, K, Ca and Mg during the flowering phase, flower yields and their cannabinoid and terpene content. For this purpose, we used two N concentrations (150 and 250 mg L -1 ) in an indoor vertical aeroponic growing system. Two genotypes were used: White Shark' (WS) and 'Critical Orange Punch' (COP). The experiment was conducted at a commercial growing facility (IsoCanMed, Louiseville, QC, Canada) during four different flowering cycles (12 672 plants per cycle) with two growing cycles for each N concentrations. Regardless of the N concentration, our results showed that the nutrient uptake of N, K and Ca increased at the beginning of the flowering phase and then decreased around the third week. On the other hand, P demand increased during the flowering phase until week 5 and then reached a plateau, while Mg uptake increased from week 1 to week 2 and then remained constant during the flowering phase. Except for week 2, no significant impact of N concentration of the nutrient uptake was observed. Increasing the N concentration from 150 to 250 mg L -1 increased plant height of both genotypes as well as the flower yield (+29%) of WS but had no significant effect on the flower yield of COP. For both genotypes, however, higher N concentration reduced by 9.5% the total THC flower content, while only little impact on terpenes was observed. Further studies are needed to identify the optimal N concentration as neither genotype responded similarly.