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The cannabis cultivation industry is facing many challenges dealing with pathogen control. This thesis investigated the use of biological control agents (BCAs) to suppress the severity and incidence of Fusarium proliferatum on cannabis in a soilless growing system. Four BCAs (Actinovate, Jumpstart, Quickroots, and Rootshield) showed strong suppression of F. proliferatum in vitro. On vegetative cannabis plants, Rootshield and Actinovate suppressed the spread of F. proliferatum on the tops of rockwool blocks. The inoculation of F. proliferatum with and without BCAs on flowering cannabis did not affect height, biomass, inflorescence yield or inflorescence cannabinoid and terpene concentrations. Further, Quickroots and Rootshield colonized cannabis roots and persisted in a soilless system more than two weeks after inoculation. Severe symptoms associated with Fusarium infection were not observed under optimal growing conditions. This thesis reports the results of several BCA tests to control F. proliferatum on cannabis, and outlines growth and quality implications.

This thesis investigated the effects of light intensity (LI) and ultraviolet (UV) radiation on indoor cannabis production during the flowering stage. When plants grew under LI ranging from 120 to 1800 μmol·m–2·s–1 provided by light emitting diodes (LEDs), inflorescence yield increased linearly as LI increased up to 1800 μmol·m–2·s–1. Apical inflorescence density and terpene concentration increased linearly over the range of LIs evaluated. When plants were grown under 400 μmol·m–2·s–1 supplemented with UV (peak wavelength of 287 nm) levels from 0.01 to 0.8 μmol·m–2·s–1, for 3.5 h·d–1, there were no changes in total Δ9-tetrahydrocannabinol or total cannabidiol concentrations. The severity of UV-induced cannabis morphology and physiology symptoms worsened as UV exposure level increased. The light response models developed in this thesis can be used to determine the optimum LI for a production environment, but caution should be used when exposing cannabis to UV radiation. This work was funded by Natural Sciences and Engineering Research Council of Canada (CRDPJ 533527 – 18).

The cannabis industry is rapidly growing, but there is a lack of scientific research for optimal lighting regimes throughout the growth cycle. This thesis explored the effects of light spectrum, intensity, and photoperiod on indoor cannabis cultivation at three different stages. Results showed that cuttings rooted under fluorescent and different light-emitting diode combinations had no effect on rooting performance during the 14-d propagation stage or on growth attributes post-transplant. During the vegetative stage, cannabis plant morphology is subjective to cultivators, but light intensities of 500-600 µmol·m-2·s-1 can be used to achieve taller plants to increase airflow, or 900-1000 µmol·m-2·s-1 can be used to achieve shorter, more compact plants for structural integrity. In vitro cannabis explants need at least 10.8 h uninterrupted dark period for floral initiation. This thesis provides useful information for cultivators to improve production by utilizing the versatility of light-emitting diodes throughout the growth cycle. 2021-12-18

Aquaponics is a growing method of agriculture which uses aquaculture effluent to fertilize mainly leafy greens and herbs. Whether this system can be used to cultivate drug-type Cannabis sativa L. has never been scientifically investigated. This thesis first evaluated C. sativa cultivation in an industry aquaponic system by comparing to a conventional hydroponic system. Results showed that aquaponically grown plants produced 42 – 116% less inflorescence yield than hydroponically grown plants, with high Na/Cl and low K/micronutrients concentrations in the aquaponic solution as potential limiting factors. Follow-up trial results showed that increasing NaCl from 4 – 40 mM in aquaponic solution decreased cannabinoid concentrations but did not affect inflorescence yield; while supplementing aquaponic solution with K at a 1 – 2:1 ratio with N, had a positive linear relationship with inflorescence yield. This research demonstrated aquaponically cultivated C. sativa is tolerant to NaCl and inflorescence yield can be increased with K supplementation. National Sciences and Engineering Research Council of Canada (Grant #533527-18) and Green Relief Inc. 2021-05-30