Evaluation of substrate composition and exogenous hormone application on vegetative propagule rooting success of essential oil hemp (Cannabis sativaL.)

Abstract

To support the rapidly expanding industrial hemp industry, a commercial supply of high-quality starter plants with low genetic variability from nurseries will be key to consistent and efficient cultivation efforts. Rooting success was evaluated across four propagation medias, five rooting hormones, and eight commercially available high-cannabidiol (CBD) essential oil hemp cultivars. Cuttings were placed in a climate-controlled room and assessed for rooting success 12 days after cloning. Rooting success was determined by quantifying total root number, cumulative total root length, and total root mass. Propagation media had the greatest effect on rooting success (13-80 %). Rockwool had the highest rooting success resulting in 10-fold increases in rooting traits over the next highest scoring medium (Berger BM6). Hormone applications significantly improved (15- to 18-fold) rooting success compared to no hormone application, while non-statistical differences were observed across auxin hormone concentrations and application methods. Genetic variation in rooting response was observed between cultivars with ‘Cherry Wine’ outperforming all other cultivars with an approximate 20% increase in rooting success over the next highest rooting cultivar, ‘Wife’. Although the ideal combination was not specifically identified in this study, findings provide insight into how rooting hormone application and medium selection impact vegetative propagule rooting success of essential oil hemp.

Impact of Indole-3-butyric Acid Concentration and Formulation and Propagation Environment on Rooting Success of ‘I3’ Hemp by Stem Cuttings

“…There was no significant difference in rooting success (P 5 0.16) between talc (88%) and IBA in solution (83%). These findings generally concur with those of Campbell et al (2021), who evaluated the effects of five different hormone treatments that included three different IBA formulations used in hemp propagation [Hormodin (OHP, Bluffton, SC), Hormex, Dip'N Grow (Dip'N Grow, Clackamas, OR)] and reported that the different rooting hormone treatments used had no significant differences in terms of rooting success. IBA formulation had a significant effect on quality for both shoots and roots (Table 2).…”

“…The 0-and 3000-ppm treatments both led to an average rooting percentage of 89%, whereas the average rooting percentage of the 8000-ppm treatment was reduced to 79%. This contrasts with Campbell et al (2021), who reported a 15-to 18fold increase in rooting with hormone compared with no hormone. IBA concentration had a significant effect (P < 0.001) on the quality scores of both roots and shoots (Table 2, Fig.…”

Copper Stimulation of Tetrahydrocannabinol and Cannabidiol Production in Hemp (Cannabis sativa L.) Is Copper-Type, Dose, and Cultivar Dependent

“…In 2018, hemp cultivation, implying Cannabis sativa plants with a THC level <0.3%, was legalized by the US government for the purpose of producing these secondary metabolites for recreational and medicinal purposes. 20,21 We recently demonstrated that THC levels escalated above the 0.3% regulatory threshold in several popular hemp cultivars during October. 22 This implies the existence of a harvest window of no later than September, and farmers of these cultivars must harvest their crop by then to be compliant, preventing embargo by regulatory authorities.…”