Response of essential oil hemp (Cannabis sativa L.) growth, biomass, and cannabinoid profiles to varying fertigation rates

Abstract

Five essential oil hemp (Cannabis sativa L.) cultivars (Cherry Blossom, Cherry Blossom (Tuan), Berry Blossom, Cherry Wine, and Cherry Blossom × Trump) were treated with six fertigation treatments to quantify the effects of synthetic fertilizer rates and irrigation electrical conductivity on plant growth, biomass accumulation, and cannabinoid profiles. Irrigation water was injected with a commercial 20-20-20 fertilizer at rates of 0, 50, 150, 300, 450, and 600 ppm nitrogen equating to 0.33 (control), 0.54, 0.96, 1.59, 2.22, and 2.85 dS m−1, respectively. Plants were grown under artificial lighting (18 hr) to maintain vegetative growth for eight weeks, followed by an eight-week flowering period. High linear relationship between chlorophyll concentrations and SPAD-502 measurements validated the utilization of SPAD meters to rapidly identify nutrient deficiency in essential oil hemp. Cultivars expressed significant variation in plant height and cannabinoid profiles (% dry mass), in concurrence with limited biomass and cannabinoid (g per plant) yield variation. Cherry Blossom was the best performing cultivar and Cherry Wine was the least productive. Variation in plant growth, biomass, and cannabinoid concentrations were affected to a greater extent by fertilizer rates. Optimal fertilizer rates were observed at 50 ppm N, while increased fertilizer rates significantly reduced plant growth, biomass accumulation, and cannabinoid concentrations. Increased fertilizer rates (> 300 ppm N) resulted in compliant THC levels (< 0.3%), although when coupled with biomass reductions resulted in minimal cannabinoid yields. Additionally, CBD concentration demonstrated higher sensitivity to increased fertilizer rates (> 300 ppm N) compared to THC and CBG (> 450 ppm N). The results of this study can serve as a guide when using fertigation methods on essential oil hemp cultivars; although results may differ with cultivar selection, environmental conditions, and management practices.

Nitrogen fertilization impact on hemp (Cannabis sativa L.) crop production: A review

“…Decarboxylated cannabinoids such as CBD and CBN (cannabinol) concentration decrease at extremely high and low N concentrations (Saloner & Bernstein, 2020). Comparable results are reported in another study where CBD and CBG (cannabigerol) yields were meager at 0 mg L −1 N. A subsequent reduction occurred when the N concentration was increased above 50 mg L −1 (Anderson et al., 2021). In a field study, it has been reported that bud biomass and CBD yield per plant increase quadratically with the increase in fertilizer N, with the optimum N range being 140–190 kg ha −1 (Atoloye et al., 2022).…”

“…Hemp is an annual, windpollinated plant with a height of 1-5 m, depending on the genotype (Bouloc et al, 2013). Nitrogen application increases plant height significantly in flower, seed, and fiber hemp under field and greenhouse conditions and has been reported in several studies (Anderson et al, 2021;Papastylianou et al, 2018;Vera et al, 2010;Yang et al, 2021;Zhu et al, 2022). N application also increases stem diameter (Yang et al, 2021;Zhu et al, 2022).…”

“…Along with CBD, other secondary metabolites are synthesized in hemp, and their concentration in the plant is affected by the mineral nutrition supplied. Flower production for CBD extraction in hemp is affected by the plant metabolism and mineral nutrition available to the plant during the vegetative growth period (Anderson et al., 2021). Establishing robust plant architecture at the vegetative growth phase improves reproduction potential and flower production (Saloner & Bernstein, 2020).…”

How do pinching and plant density affect industrial hemp produced for cannabinoids in open field conditions?

“…Environmental factors, such as soil temperature, air humidity, and precipitation, affected total CBD and total THC concentration in flowers of IH in different ways under open field conditions (Sikora et al, 2011). In addition, studies in controlled environments reported that total CBD and total THC concentration in cannabis plants responded to different fertilization treatments (Anderson et al, 2021;Bócsa et al, 1997;Caplan et al, 2017;Coffman & Gentner, 1975, 1977. Taken together, these results provide a strong incentive to elucidate genetic stability of cannabinoid content in high-CBD hemp cultivars across different field-scale production systems.…”

Cannabidiol industrial hemp growth, biomass, and temporal cannabinoids accumulation under different planting dates in southern Florida

“…Hence, there has been significant interest in cultivating CBD‐dominant hemp cultivars for their medicinal uses. Many studies are being conducted to identify suitable cultivars and cultural practices for CBD‐dominant industrial hemp cultivation in different agroclimatic regions including Florida (Anderson et al., 2021; Yang et al., 2020; Zhang et al., 2021). However, in several areas such as Florida, high CBD yielding cultivars are also accompanied with high THC concentrations (Yang et al., 2020).…”