Page 192 - PC2019 Program & Proceedings

PLANT CANADA 2019

S169. Variation in rootzone environment influences growth and yield of drug-type cannabis
cultivars during the flowering stage
*1
2
Yep, B. ; N.V. Gale ; Y. Zheng
1
2
1 University of Guelph; Green Relief
Cannabis cultivators use diverse production systems and rootzone management strategies in indoor
cannabis production. To investigate the impact of rootzone environments on the growth and yield of two
drug-producing cultivars, three rootzone environments were applied to 60 cannabis plants during the
flowering stage, using a randomized block design. The rootzone environments tested were: 1) an 11-litre
pot containing a peat based growing substrate, top fertigated with a synthetic fertilizer solution
(“hydroponic”); 2) an 11-litre pot containing a peat based growing substrate, top fertigated with
aquaculture effluent solution (“aquaculture”); and 3) a 3-litre pot containing a custom made growing
substrate, sub-irrigated with aquaculture effluent solution (“aquaponics”). The experiment was conducted
at Green Relief, a licensed indoor cannabis facility in Puslinch Ontario. Cultivar ‘Nordle’ grown via
hydroponic rootzone had 41% and 116% higher floral biomass (at 13% moisture content) than plants
grown with aquaculture and aquaponics, respectively. Similarly, cultivar ‘Sensistar’ grown with
hydroponics had 61% higher floral biomass than plants grown with the other two rootzones. In contrast,
however, Nordle plants grown with aquaponics had significantly higher floral tissue concentrations of
total THC and CBD compared to the other two rootzones investigated. Leaf tissue and rootzone nutrient
analyses suggests that differences in nutrient supply was a primary factor causing the observed
differences within cultivars. Differences in floral yield across cultivars can be attributed to phenotypic
differences.

Brandon Yep (byep@uoguelph.ca)

S170. Diseases that can devastate Cannabis sativa production – bud rots, powdery mildew and root
and crown rots.
Punja, Z.
Simon Fraser University

Cannabis (Cannabis sativa L.) is cultivated by licensed producers in Canada under greenhouse and indoor
environments. With the increasingly large-scale production of cannabis, a number of pathogens and
molds that reduce yield and quality have been identified within several facilities and are described here.
Isolations were performed from diseased tissues and colonies were identified using PCR of the ITS1-
5.8S-ITS2 region. Botrytis bud rot (Botrytis cinerea) affected inflorescences at the flowering stage and
caused a post-harvest disease. Powdery mildew (Golovinomyces chicoracearum) infected the foliage and
inflorescences. Root and crown rots on stock (mother) plants and on vegetative and flowering plants were
caused by several species of Fusarium and Pythium, including Fusarium oxysporum, F. solani, F.
proliferatum, F. brachygibbosum, Pythium dissotocum, P. myriotylum, P. ultimum and P.
aphanidermatum. Symptoms included root browning, discoloration of crown and pith tissues, stunting
and yellowing, and in some instances, plant death. The most prevalent pathogens were F. oxysporum and
P. myriotylum, particularly on plants in the vegetative growth phase. Differences in disease severity were
observed between cannabis strains (genotypes) for bud rot and powdery mildew, but not for root and
crown rots. The epidemiology and management of these diseases will be discussed. They include
sanitation practices, management of water regimes, application of biological control agents, and selection
of cannabis strains.

Zamir Punja (punja@sfu.ca)

Page 190 of 339