Abstract
In the expanding North American medical cannabis industry, growers lack reliable and systematically investigated information on the horticultural management of their crops, especially with regard to nutrient management and growing substrates. To evaluate organic substrates and their optimal nutrient management, five rates that supplied 57, 113, 170, 226, and 283 mg N/L of a liquid organic fertilizer (2.00N–0.87P–3.32K) were applied to container-grown plants [Cannabis sativa L. ‘WP:Med (Wappa)’] in two coir-based organic substrates. The trial was conducted in a walk-in growth chamber and the two substrates used were ABcann UNIMIX 2-HP (U2-HP) with lower container capacity (CC) and ABcann UNIMIX 2 (U2) with higher CC. U2-HP produced 11% higher floral dry weight (yield), 13% higher growth index (GI), 20% higher ∆9-tetrahydrocannabinol (THC) concentration, 57% higher THC yield (per plant), 22% higher Δ9-tetrahydrocannabidiolic acid (THCA) yield, and 20% higher cannabigerolic acid (CBGA) yield than U2. Increasing fertilizer rate led to increased growth and yield but also to a dilution of THC, THCA, and CBGA. In U2-HP, to maximize both yield and cannabinoid yield, the optimal organic fertilizer rates were those which supplied 212–261 mg N/L. For U2, the highest applied rate, that supplied 283 mg N/L, maximized yield; although lower rates delivered higher cannabinoid concentrations in dry floral material. The results on these substrates and recommended fertilizer rates can serve as a guide when using other organic fertilizers and substrates; although results may differ with cannabis variety.
Highlights
In the expanding North American medical cannabis industry, growers lack reliable and systematically investigated information on the horticultural management of their crops, especially with regard to nutrient management and growing substrates
Our results suggest that to produce highyielding, cannabinoid-rich, organic cannabis plants, lower CC coir-based substrates, such as UNIMIX 2-HP (U2-HP), are preferable to those with higher CC, such as UNIMIX 2 (U2)
The drier substrate produced higher floral yield, growth index (GI), THC concentration, THC yield, tetrahydrocannabidiolic acid (THCA) yield, and cannabigerolic acid (CBGA) yield than U2, possibly because of higher fertigation frequency or adequate root zone oxygen leading to a more favorable root zone environment
Summary
In the expanding North American medical cannabis industry, growers lack reliable and systematically investigated information on the horticultural management of their crops, especially with regard to nutrient management and growing substrates. For U2, the highest applied rate, that supplied 283 mg N/L, maximized yield; lower rates delivered higher cannabinoid concentrations in dry floral material. The results on these substrates and recommended fertilizer rates can serve as a guide when using other organic fertilizers and substrates; results may differ with cannabis variety. Cannabinoids exist predominantly as carboxylic acids such as D9-THCA and cannabidiolic acid (CBDA) (Muntendam et al, 2012) These acids decarboxylate during storage (Ross and ElSohly, 1997; Taschwer and Schmid, 2015) and upon heating (Kimura and Okamoto, 1970) to become neutral cannabinoids such as THC and CBD. Varieties with high THC and low CBD are termed marijuana or drug-type cannabis (van Bakel et al, 2011; Vollner et al, 1986), hereafter referred to as cannabis
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
