Nutrient management during the flowering pliase of drug-type Cannabis sativa

摘要

Identifying the plant nutrient uptake under different N concentrations and evaluating the impact of P and K supply.During the last few years, an increasing number of studies have evaluated the impact of the mineral nutrition on growth, flower yield and cannabinoid and terpenoid profiles of cannabis.As a result, scientific-based N, P and K optimal ranges have been proposed. However, little is now about the nutrient uptake of cannabis during its development.To determine the nutrient requirement of drug-type cannabis during the flowering phase, we studied at the commercial site (IsoCanMed Inc., Louiseville, Que.) the impact of two N concentrations (150 and 250 ppm) on plant growth development, plant nutrient uptake of N, K, Ca and Mg, flower yield andtheir cannabinoid and terpene content. Six growth cycles were performed in a vertical indoor aeroponic growing system with two high THC genotypes (Critical Orange Punch, COP, and White Shark, WS) (figures 1A-D). The plantlets were transferred into a flowering room having 42 vertical aeroponic towers (264 plants per tower; total of 12,672 plants per growth cycle) and submitted to a vegetative phase (16-h photoperiod) of two weeks or directly submitted to the flowering phase (12-h photoperiod; PPFD of 445pmol nr2 s'1 provided by 1000 W HPS and 315 W LEC lamps; 500-1500 ppm C02; day/night temperature of 22/18°C; 55-70 RH). Plants were irrigated with a complete nutrient solution, which was collected into a 2,000 L reservoir and reused. Twice a day, thenutrient solution was adjusted for the EC and pH, and the plant nutrient consumption was measured daily (samples taken before and after the nutrient solution adjustment).