Biochemical and physiological responses of Cannabis sativa to an integrated plant nutrition system

The illegal status of cannabis (Cannabis sativa L.) post-World War II resulted in a lack of research on agricultural practices. However, there is a resurgence of interest in cannabis due to diverse uses such as a rich source of cellulosic/woody fiber and construction uses, seed oil, bioenergy and pharmaceutical properties. The principle of an integrated plant nutrition system (IPNS) is to enable adaptation of plant nutrition and soil fertility management to local site characteristics, attempting to optimize use of inorganic, organic and biological resources. This project investigated the individual and combined use of inorganic, organic and biological fertilizer resources on cannabis before and after a period of moderate water stress. We evaluated the individual and combined effects of commercial synthetic fertilizer, humic acid (HA), manure tea and bioinoculant as inorganic, organic and biological resources, respectively on cannabis growth and physiological parameters. Our hypothesis was that the synergetic effects of HA + biofertilizers would improve cannabis growth. When compared to the control, the application of HA and biofertilizer alone, or in combination, increased plant height, chlorophyll content and photosynthetic efficiency by 55, 8 and 12%, respectively, after water stress. Cannabis biomass of treated plants was rarely different from the control. The combined application of HA + biofertilizer resulted in additive, but not synergistic, increases in measured parameter. Future research should focus on the effects of biostimulants on CBD/THC content due to the potential impact on the production of secondary metabolites in plants under stress.