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The various Cannabis taxa (indicated by their acronyms, see Figure 1) have been spread by humans into nearly every part of the world; PA? = putative Cannabis ancestor (from Clarke and Merlin, 2013).
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Humans and the Cannabis plant share an intimate history spanning millennia. Humans spread Cannabis from its Eurasian homelands throughout much of the world, and, in concert with local climatic and human cultural parameters, created traditional landrace varieties (cultivars resulting from a combination of natural and farmer selection) with few appar...
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The golden age of cannabis pharmacology began in the 1960s as Raphael Mechoulam and his colleagues in Israel isolated and synthesized cannabidiol, tetrahydrocannabinol, and other phytocannabinoids. Initially, THC garnered most research interest with sporadic attention to cannabidiol, which has only rekindled in the last 15 years through a demonstra...
This chapter has two parts. The first part details five characters that contribute to phenotypic diversity in Cannabis. Cannabinoids can be assayed by quantity (dry weight percentage of cannabinoids in harvested material) or by quality (the THC/CBD ratio, or chemotype). Cannabinoid quality is largely genetic, possibly monogenic. We dissect the mono...
There has been an increased use of medical Cannabis in the United States of America as more states legalize its use. Complete chemical analyses of this material can vary considerably between producers and is often not fully provided to consumers. As phytochemists in a state with legal medical Cannabis we sought to characterize the accumulation of p...
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... Cannabis sativa is a dioecious, annual, short-photoperiod plant [17,18]. In short-day plants, the photoperiod controls steps of the flowering mechanism such as flower induction or inflorescence elongation. ...
Recent studies have demonstrated dose-responses of the cannabis plant to supply of macronutrients. However, further development of precision nutrition requires a high-resolution understanding of temporal trends of plant requirements for nutrients throughout the developmental progression, which is currently not available. As plant function changes during development, temporal information on nutrient uptake should be considered in relation to gradients in developmental-related physiological activity. Therefore, the present study investigated tempo-developmental trends of nutritional demands in cannabis plants, and in relation to physiological performance. Three cultivars differing in phenotype and chemotype were analyzed to evaluate genotypic variability. The results demonstrate that nutrient acquisition and deposition rates change dramatically during plant development. Uptake of individual minerals generally increased with the progression of both vegetative and reproductive development and the increase in plant biomass, while the deposition rates into the plant demonstrated nutrient specificity. The average concentrations of N, P, and K in the shoots of the different cultivars were 2.33, 4.90, and 3.32 times higher, respectively, at the termination of the reproductive growth phase, compared to the termination of the vegetative growth phase. Surprisingly, the uptake of Ca was very limited during the second part of the reproductive growth phase for two cultivars, revealing a decrease in Ca demand at this late developmental stage. Root-to-shoot translocation of most nutrients, including P, K, Mg, Mn, and Zn, as well as Na, is higher during the reproductive than the vegetative growth phase, and Fe, Mn, Zn, Cu, and Na displayed very little root-to-shoot translocation. The physiological characteristics of the plants, including gas exchange parameters, membrane leakage, osmotic potential, and water use efficiency, changed over time between the vegetative and the reproductive phases and with plant maturation, demonstrating a plant-age effect. The revealed tempo-developmental changes in nutritional requirements of the cannabis plant are a powerful tool required for development of a nutritional protocol for an optimal ionome.
... Prohibition on the growth and use of C. sativa throughout human history has inhibited our understanding of this economically valuable species [24][25][26][27][28]. Modern research has often focused on female plants [29][30][31][32][33], leaving a gap in our understanding of male plants, cosexual plants, male-male competition, and factors that impact male reproductive dynamics. ...
Cannabis sativa L. is cultivated globally for its cannabinoid-dense inflorescences. Commercial preference for sinsemilla has led to the development of methods for producing feminized seeds through cross-pollination of cosexual (masculinized) female plants. Although the induction of cosexuality in Cannabis plants is common, to date, no work has empirically tested how masculinization of female Cannabis plants impacts male flowering, pollen production, pollen fitness, and related life-history trade-offs. Here, we cultivated a population of Cannabis plants (CFX-2) and explored how the route to cosexuality (drought vs. chemical induction) impacted flowering phenology, pollen production, and pollen fitness, relative to unsexual male plants. Unisexual males flowered earlier and longer than cosexual plants and produced 223% more total pollen (F2,28 = 74.41, p < 0.001), but per-flower pollen production did not differ across reproductive phenotypes (F2,21 = 0.887, p = 0.427). Pollen viability was 200% higher in unisexual males and drought-induced cosexuals (F2,36 = 189.70, p < 0.001). Pollen non-abortion rates only differed in a marginally significant way across reproductive phenotypes (F2,36 = 3.00, p = 0.06). Here, we demonstrate that masculinization of female plants impacts whole-plant pollen production and pollen fitness in Cannabis sativa.
... C. sativa is a highly variable crop (Clarke and Merlin, 2016;Small, 2018) and Parson et al. (2019), as well as Kurtz et al. (2020), showed that the response of C. sativa to polyploidization induction is genotype and cultivar dependent. Additionally, observations of Parsons et al. (2019) and Crawford et al. (2021) on cannabinoid concentrations hinted that polyploidization might affect secondary metabolite quantity differently, likely dependent on the starting plant material. ...
Cannabis sativa L. is a plant with a wide range of potential medicinal applications. In recent years, polyploidy has gained attention as a potential strategy for rapidly improving C. sativa , which, unlike other modern crops, has not yet benefitted from this established biotechnological application. Currently, no reports on high THCA and CBDA drug-type polyploid cultivars have been published. Moreover, it still needs to be clarified if different cultivars react similarly to polyploidization. For these reasons, we set out to evaluate and compare the phenotype and chemotype of three high Δ ⁹ -tetrahydrocannabinolic acid (THCA) and one high cannabidiolic acid (CBDA) drug-type cultivars in their diploid, triploid and tetraploid state through agronomic and metabolomic approaches. Our observations on plant morphology revealed a significant increase in plant height and leaf size with increasing ploidy levels in a cultivar-dependent manner. In contrast, cannabinoids were negatively affected by polyploidization, with the concentration of total cannabinoids, THCA, CBDA and cannabigerolic acid (CBGA) decreasing significantly in higher ploidy levels across all four cultivars. Headspace analysis of volatiles revealed that total volatile content decreased in triploids. On the other hand, tetraploids reacted differently depending on the cultivars. Two THCA dominant cultivars showed an increase in concentrations, while in the other two cultivars, concentrations decreased. Additionally, several rare compounds not present in diploids appeared in higher ploidy levels. Moreover, in one high THCA cultivar, a couple of elite tetraploid genotypes for cannabinoid and volatile production were identified, highlighting the role of cultivar and genotypic variability as an important factor in Cannabis sativa L. polyploids. Overall, our observations on plant morphology align with the giga phenotype observed in polyploids of other plant species. The decrease in cannabinoids and volatiles production in triploids have relevant implications regarding their commercial use. On the other hand, this study found that tetraploidization is a suitable approach to improve Cannabis sativa L. medicinal potential, although the response is cultivar and genotype-dependent. This work lays the ground for further improving, evaluating and harnessing Cannabis sativa L. chemical diversity by the breeding, biotechnological and pharmaceutical sectors.
... Cannabis (Cannabis sativa L.) is a dicotyledonous angiosperm originating from Central Asia but is cultivated across many parts of the world due to its ability to grow in a wide range of habitats and environmental conditions [1]. ...
Cannabis (Cannabis sativa L.) is one of the earliest cultivated crops, valued for producing a broad spectrum of compounds used in medicinal products and being a source of food and fibre. Despite the availability of its genome sequences, few studies explore the molecular mechanisms involved in pathogen defense, and the underlying biological pathways are poorly defined in places. Here, we provide an overview of Cannabis defence responses against common pathogens, such as Golovinomyces spp., Fusarium spp., Botrytis cinerea and Pythium spp. For each of these pathogens, after a summary of their characteristics and symptoms, we explore studies identifying genes involved in Cannabis resistance mechanisms. Many studies focus on the potential involvement of disease resistance genes, while others refer to other plants however whose results may be of use for Cannabis research. Omics investigations allowing the identification of candidate defence genes are highlighted, and genome editing approaches to generate resistant Cannabis species based on CRISPR/Cas9 technology are discussed. According to the emerging results, a potential defence model including both immune and defence mechanisms in Cannabis plant-pathogen interactions is finally proposed. To our knowledge, this is the first review of the molecular mechanisms underlying pathogen resistance in Cannabis.
... The accumulation of cannabinoids is dependent on the plant age and tissue type: the highest concentrations are found in the glandular trichomes of the female flowers and small leaves clustered within the inflorescence (Kim and Mahlberg 1997). Significant effort has been dedicated in breeding C. sativa varieties with traits beneficial for agricultural production, including higher cannabinoid yields (Clarke and Merlin 2016). ...
... Furthermore, chemotypes do not necessarily constitute a phylogenetic classification based on evolutionary relationship. The dioecy of the plant leads to high levels of heterozygosity even within a single cannabis variety (Clarke and Merlin 2016;Schilling et al. 2021) and, unlike previously assumed, many morphological traits (e.g., leaf shape) do not correlate with phytochemistry (Vergara et al. 2021). Many traits important for plant growth, development, and stress resilience have not been examined in detail. ...
i>Cannabis sativa is one of the oldest cultivated crops, used for its fiber and medicinal properties. The cannabis plant synthesizes a myriad of secondary metabolites, but the most valuable products from a medical and commercial standpoint are cannabinoids. Despite significant advances in elucidating the biochemistry and genetics that govern cannabinoid accumulation, we still do not have conclusive evidence for the role of these secondary metabolites in the physiology of C. sativa . In line with known functions of other secondary metabolites, the protective functions of cannabinoids against temperature stress, poor micronutrient soil content, drought, UV-B radiation, and as anti-microbial agents have been suggested, but are yet to be conclusively demonstrated. Recent research suggests that the environment has a major effect on cannabis growth and productivity, but the relationship between stress, cannabinoid accumulation, and plant health is complex. Here, we summarize the current insights on how abiotic and biotic stress affect C. sativa biology. We also examine the available evidence to support the hypothesis for the protective function of cannabinoids against environmental stressors. Maintaining optimal growth and high cannabinoid synthesis is a balancing act, one that can only be achieved by better understanding of the effects on the environment on the cannabis plant.
... Plants in the cannabis genus are generally characterized as having short-day photoperiod responses (Zhang et al., 2021) [1], whereby reductions in daylength to a certain timeframe provoke flowering responses. However, cannabis' widespread cultivation and breeding across many geographic regions have naturally led to substantial genotypic differences in photoperiodic responses (Clarke and Merlin, 2016;Zhang et al., 2018) [2,3]. These varying photoperiod responses have been exploited in different cultivation scenarios. ...
... Plants in the cannabis genus are generally characterized as having short-day photoperiod responses (Zhang et al., 2021) [1], whereby reductions in daylength to a certain timeframe provoke flowering responses. However, cannabis' widespread cultivation and breeding across many geographic regions have naturally led to substantial genotypic differences in photoperiodic responses (Clarke and Merlin, 2016;Zhang et al., 2018) [2,3]. These varying photoperiod responses have been exploited in different cultivation scenarios. ...
Cannabis sativa (“cannabis” hereafter) is a valuable recent addition to Canada’s economy with the legalization for recreational use in 2018. The vast majority of indoor cannabis cultivators use a 12-h light/12-h dark photoperiod to promote flowering. To test the hypothesis that robust flowering initiation responses can be promoted in indoor-grown cannabis cultivars under longer photoperiods, clones of ten drug-type cannabis cultivars were grown under six photoperiod treatments. All treatments were based on a standard 24-h day and included 12 h, 12.5 h, 13 h, 13.5 h, 14 h, and 15 h of light. The plants were grown in a growth chamber for 3 to 4 weeks, receiving an approximate light intensity of 360 µmol·m−2·s−1 from white LEDs. Flowering initiation, defined as the appearance of ≥3 pairs of stigmas at the apex of the primary shoot, occurred in all cultivars under all photoperiod treatments up to 14 h. Delays in flowering initiation time under 14 h vs. 12 h ranged from no delay to approximately 4 days, depending on the cultivar. Some cultivars also initiated flowering under 15 h, but floral tissues did not further develop beyond the initiation phase. Harvest metrics of some cultivars responded quadratically with increasing photoperiod, with ideal levels of key flowering parameters varying between 12 h and 13 h. These results suggest there is potential to increase yield in some indoor-grown cannabis cultivars by using longer than 12-h photoperiods during the flowering stage of production. This is attributed to the inherently higher daily light integrals. Indoor cannabis growers should investigate the photoperiod responses of their individual cultivars to determine the optimal photoperiod for producing floral biomass.
... Hemp varieties with high cannabidiol (CBD) concentrations are often selected for medicinal and therapeutic uses. There is also a focus on developing varieties that are day-neutral (DN) or minimally sensitive to photoperiod in order to expand production opportunities [4]. ...
Heavy metal contamination of agricultural soils is potentially concerning when growing crops for human consumption. Industrial hemp (Cannabis sativa L.) has been reported to tolerate the presence of heavy metals such as cadmium (Cd) in the soil. Therefore, the objectives of this study were to evaluate Cd uptake and translocation in two day-length sensitive (DLS) and two day-neutral (DN) hemp varieties grown for the medicinal market and to determine the impact of Cd exposure on cannabinoid concentrations in flowers. A hydroponic experiment was conducted by exposing plants to 0 mg·L−1 Cd and 2.5 mg·L−1 Cd in the nutrient solution. Cadmium concentrations ranged from 16.1 to 2274.2 mg·kg−1 in roots, though all four varieties accumulated significant concentrations of Cd in aboveground tissues, with translocation factors ranging from 6.5 to 193. Whole-plant bioconcentration factors ranged from 20 to 1051 mg·kg−1. Cannabinoid concentrations were negatively impacted by Cd exposure in DN varieties but were unaffected in DLS varieties. Biomass was reduced by Cd exposure demonstrating that these varieties might not be suitable for growth on contaminated soil or for phytoremediation. There is potential for Cd accumulation in flowers, showing the need for heavy metal testing of C. sativa consumer products.
... Cannabis sativa L. belongs to the family Cannabaceae, and it is among the first plants to be cultivated. Its uses include fiber, fuel, food, cosmetics, and medicine [1]. Drug-type cannabis contains a range of bioactive compounds, including cannabinoids, terpenoids, and alkaloids [2]. ...
Cannabis sativa L. is typically propagated through micropropagation or vegetative cuttings, but the use of root-inducing hormones, such as indole-3-butyric acid (IBA), is not allowed for growing medicinal cannabis in Denmark. This study examined alternative rooting treatments, including Rhizobium rhizogenes inoculation, water-only as well as IBA treatments, in eight cannabis cultivars. PCR on root tissue suggested that 19% of R. rhizogenes-inoculated cuttings were transformed. These were derived from “Herijuana”, “Wild Thailand”, “Motherlode Kush”, and “Bruce Banner”, indicating a variation in cultivar susceptibility toward R. rhizogenes. A 100% rooting success was achieved regardless of cultivar and treatment, suggesting that alternative rooting agents are not required for efficient vegetative propagation. However, rooted cuttings differed in shoot morphology with improved shoot growth in cuttings treated with R. rhizogenes (195 ± 7 mm) or water (185 ± 7 mm) while inhibited shoot growth under IBA treatment (123 ± 6 mm). This could have advantageous economic implications should cuttings not treated with hormone reach maturity faster than those exposed to the hormone, thereby contributing to completing a full growing cycle more effectively. IBA exposure increased root length, root dry weight, and root/shoot dry weight ratio compared to cuttings treated with R. rhizogenes or water but simultaneously inhibited shoot growth compared to these.
... Cannabis exhibits genetic and phenotypic diversity and is a multipurpose plant with a variety of uses, including food, fiber, construction materials, paper, and biofuel, and has various pharmacological properties that can be absorbed by the body through different forms (e.g., vaporizers, joints, edibles, smoothies, capsules, sprays, tinctures and ointments (Clarke and Merlin 2016). Cannabis for medical purposes has gained increasing interest (Manthey 2019;Pratt et al. 2019;Treister-Goltzman et al. 2019), resulting in a variety of therapeutic products based on single or multiple cannabinoids (e.g., Cannabidiol (CBD), tetrahydrocannabinol (THC)). ...
Growing evidence on medical cannabis has moved its legislation forward in various countries, which has increased research on stakeholder reactions. While various studies looked at experts and users, research on public perceptions is scarce. This study aims to (1) examine the relationships between knowledge, perceptions, and behavioral intention toward medical cannabis, and (2) identify and profile key segments within the general public. An online survey was conducted among 656 respondents in Belgium. Findings showed that both subjective and objective knowledge are relatively poor, while risk/benefit perceptions and behavioral intention are much more positive. Subjective and objective knowledge as well as social trust have a positive influence on risk perceptions and a negative influence on benefit perceptions. In turn, risk and benefit perceptions are key determinants of behavioral intention, but in opposite directions. Furthermore, cluster analysis identified a cautious (23% of the sample), positive (50%), and enthusiastic cluster (27%). In terms of socio-demographic profile, older and highly educated people were significantly more represented in the latter two clusters. While our study demonstrated that cannabis is well accepted for medical purposes, research is needed to further validate the relationships between knowledge, perceptions, and (intended) behavior in different settings and policy contexts.
... Insect repellent properties can be used to produce pesticides. After it's domestication in China, hemp was introduced across the world [6,7]. Currently, it is mainly grown in temperate countries and according to the FAOSTAT database, the seed yield data are available for 6 countries; Chile, China, Iran, Russian Federation, Turkey and Ukraine [8]. ...
Hemp (Cannabis sativa L.) is a multi-million-dollar industry in several temperate countries. In South and Southeast Asian region, it remains a neglected and underutilised due to several legal, political, and cultural barriers. Therefore, very limited research has been done on value chain of hemp in this region. Nevertheless, as discussions are ongoing on the legalization of hemp in some of the countries in the region, interest in research and development of hemp is growing. The objective of this review is to identify what has been done on hemp in the region and outline the potentials and challenges in adopting hemp as an industrial crop in tropical South and Southeast Asia. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to select and review research articles. Out of the 12,210 studies, 36 were selected for review and analysis. The results demonstrate the potential of hemp in the South and Southeast Asian region in terms of genetic diversity, growth habits, environmental and health benefits, and value-added products. To motivate the commercial cultivation, several key aspects were identified that includes development of region/location specific cultivars, introduction of site/cultivar specific management practices and development of proper market facilities. The review concludes that hemp can be a potential candidate for crop diversification across South and Southeast Asia.
