Effects of short-term environmental stresses on the onset of cannabinoid production in young immature flowers of industrial hemp (Cannabis sativa L.)

Abstract

Backgrounds Cannabis sativa L. produces at least 120 cannabinoids. Although genetic variation is the main factor in cannabinoid production, the effects of short-term environmental stresses in the early flowering stage remains largely unknown. Methods To investigate the effects of short-term environmental stresses on the onset of cannabinoid production in young immature flowers, a hemp variety, Green-Thunder (5–8% CBD/mg of dry weight), was treated with mechanical damage, insect herbivory, extreme heat, or drought stress for 5–7 days during the first 2 weeks of flowering. Three hemp tissues, including flowers, leaves, and stems, were collected from hemp grown under these stress conditions at multiple time points during the first 2 weeks after transition to the short photoperiod and analyzed using high pressure liquid chromatography to quantify phytocannabinoids including cannabigerolic acid (CBGA), cannabigerol (CBG), cannabidiolic acid (CBDA), cannabidiol (CBD), Δ-tetrahydrocannabinolic acid (THCA), Δ-tetrahydrocannabinol (THC), and cannabinol (CBN). Results The 5 days of mechanical wounding did not affect the production of any of the cannabinoids during the initial stage of flowering. However, after 5 days of herbivore treatment, there was a significant difference in concentration between day 1 and day 6 of CBGA (control: 308 μg/g; treatment – 24 μg/g), CBG (control: 69 μg/g; treatment: 52 μg/g), and CBD (control: 755 μg/g; treatment: 194 μg/g) between the control and treatment plants. The 7 days of heat treatment at 45–50 oC significantly reduced the production of CBGA during this observed window (control: 206 μg/g; treatment: 182 μg/g) and CBG (control: 21 μg/g; treatment: − 112 μg/g). Notably, the largest change was observed after 7 days of drought stress, when plants showed a 40% greater accumulation of CBG (control: 336 μg/g; treatment: 622 μg/g), and a significant decrease (70–80%) in CBD (control: 1182 μg/g; treatment: 297 μg/g) and THC amounts (control: 3927 μg/g; treatment: 580 μg/g). Conclusions Although this observation is limited in the early flowering stage, the common field stresses are adequate to induce changes in the cannabinoid profiles, particularly drought stress being the most impactful stress for hemp flower initiation with the altering the cannabinoid production by decreasing CBD and THC accumulation while increasing CBG by 40%.

Agronomic, phytochemical and drought tolerance evaluation of Iranian cannabis (Cannabis sativa L.) ecotypes under different soil moisture levels: a step towards identifying pharmaceutical and industrial populations

“…CBG is a shared precursor molecule to the production of both CBD and THC. The increase of CBG accumulation, resulting in accumulation of cannabigrolic acid (CBGA) that was decarboxylated under stress conditions (Park et al . 2022).…”

Biology and management of hemp russet mite (Acari: Eriophyidae)

“…Interestingly, the presence of a different mite species, twospotted spider mites ( T. urticae ), on hemp had the opposite effect, leading to an increase in CBD and THC levels (Kostanda and Khatib 2022). Tobacco hornworm infestation, however, is more similar to HRM in that cannabinoid levels, specifically CBD and CBGA, were reduced relative to healthy plants (Park et al 2022). These results highlight the need for further investigation into the role of cannabinoids and other specialized metabolites in multiple pest species to understand the full spectrum of the effects.…”

Effect of High-Tunnel and Open-Field Production on the Yield, Cannabinoids, and Volatile Profiles in Industrial Hemp (Cannabis sativa L.) Inflorescence

“…21 The results revealed that cultivar type significantly influences the flower yield and total cannabinoid content, with Cherry Blossom yielding a high flower yield and Cherry XT1 showcasing the highest cannabinoid production. Several other studies have highlighted cultivar type, 22,23 environmental stress, 24 genotype, 25 and genotype × environment interactions 26 as important factors influencing hemp flower yields and bioactive compound production. However, the studies focusing on the influence of production practice on the hemp flower yield, cannabinoid content, and volatile profile are far from adequate.…”