Search Results (8)

Hop latent viroid (HLVd), a 256-nucleotide RNA strand with complementary base-pairing and internal stem loop structures, forms circular or rod-shaped molecules within diseased plants. RT-PCR/RT-qPCR was used to assess HLVd transmission, spread and longevity. The viroid was detected in asymptomatic stock plants and in rooted vegetative cuttings, as well as in recirculated nutrient solution sampled from propagation tables and nozzles. Plant-to-plant spread through root infection in hydroponic cultivation was demonstrated. The viroid survived for 7 days and 4 weeks, respectively, in crushed leaf extracts (sap) or dried leaves/roots at room temperature. Following stem inoculation with infectious sap, HLVd was detected in root tissues within 2–3 weeks and in the foliage within 4–6 weeks. Plants grown under a 12:12 h photoperiod to induce inflorescence development showed more rapid spread of HLVd compared to 24 h lighting. The viroid was subsequently detected in inflorescence tissues, in trichome glands, in dried cannabis flowers and in crude resinous oil extracts. Anthers and pollen from infected male plants and seeds from infected female plants contained HLVd, giving rise to up to 100% infected seedlings. Artificially inoculated tomato and tobacco plants supported viroid replication in roots and leaves. Infected cannabis leaf and root tissues treated with UV-C for 3–5 min or temperatures of 70–90 °C for 30 min contained amplifiable HLVd-RNA. Infectious plant extract treated with 5–10% bleach (0.825% NaOCl) or 1000 ppm hypochlorous acid yielded no RT-PCR bands, suggesting the RNA was degraded. Meristem tip culture from HLVd-infected plants yielded a high frequency of pathogen-free plants, depending on the genotype. Full article

Cannabis (Cannabis sativa L.) is one of the earliest cultivated crops and is valued for its medicinal compounds, food, fibre, and bioactive secondary metabolites. The rapid expansion of the cannabis industry has surpassed the development of production system knowledge. The scientific community currently focuses on optimising agronomic and environmental factors to enhance cannabis yield and quality. However, cultivators face significant challenges from severe pathogens, with limited effective control options. The principal diseases include root rot, wilt, bud rot, powdery mildew, cannabis stunt disease, and microorganisms that reduce post-harvest quality. Sustainable management strategies involve utilising clean planting stocks, modifying environmental conditions, implementing sanitation, applying fungal and bacterial biological control agents, and drawing on decades of research on other crops. Plant–microbe interactions can promote growth and regulate secondary metabolite production. This review examines the recent literature on pathogen management in indoor cannabis production using biocontrol agents. Specific morphological, biochemical, and agronomic characteristics hinder the implementation of biological control strategies for cannabis. Subsequent investigations should focus on elucidating the plant–microbe interactions essential for optimising the effectiveness of biological control methodologies in cannabis cultivation systems. Full article

The approaching legalisation and associated increasing demand for medicinal and recreational Cannabis sativa L. will lead to a growing relevance for lighting systems designed for Cannabis sativa L. The interplay between plant density, light spectrum, light distribution, yield, and secondary metabolite distribution within the plant has not yet been studied. To fill this knowledge gap, a CBD-dominant Cannabis sativa L. strain was grown in a greenhouse experiment with two plant densities (2.66 and 12 plants ⁻¹ m⁻²) under two different light spectra. The chosen light spectra were two LED fixtures, Solray385 (SOL) and AP67, with an R: FR ratio of 12.9 and 3.7, respectively. The results indicated that light-induced effects on individual plants can be transferred to the plant stock. A low R: FR ratio induced a 16% increase in dry flower yield in the last ten days of flowering, while a change in the light spectrum could increase the potential maximum plant density per square metre. The two spectra did not affect (CBD + CBDA) yield, as a lower flower yield compensated for a higher concentration. CBDA concentration was not significantly affected by plant density. In contrast, the higher density led to an increased total cannabidiol concentration (CBD + CBDA) and altered the distribution of terpenes. Here, the light distribution over the plant stock is particularly decisive, as a more homogenous illumination led to an increased terpene concentration of up to 41%. A Photon Conversion Efficacy (PCE) of 0.05 g mol⁻¹ under SOL and 0.06 g mol⁻¹ under AP67 was achieved. Plants in the centre under the highest light intensity of 1200 PAR showed up to 48% reduced efficacy. These results strongly suggest that light intensity needs to be fine-tuned to the cultivation system to prevent a reduction in efficacy, resulting in yield and quality losses. Full article

The increased cultivation of high THC-containing Cannabis sativa L. (cannabis), particularly in greenhouses, has resulted in a greater incidence of diseases and molds that can negatively affect the growth and quality of the crop. Among them, the most important diseases are root rots (Fusarium and Pythium spp.), bud rot (Botrytis cinerea), powdery mildew (Golovinomyces ambrosiae), cannabis stunt disease (caused by hop latent viroid), and a range of microbes that reduce post-harvest quality. An integrated management approach to reduce the impact of these diseases/microbes requires combining different approaches that target the reproduction, spread, and survival of the associated pathogens, many of which can occur on the same plant simultaneously. These approaches will be discussed in the context of developing an integrated plan to manage the important pathogens of greenhouse-grown cannabis at different stages of plant development. These stages include the maintenance of stock plants, propagation through cuttings, vegetative growth of plants, and flowering. The cultivation of cannabis genotypes with tolerance or resistance to various pathogens is a very important approach, as well as the maintenance of pathogen-free stock plants. When combined with cultural approaches (sanitation, management of irrigation, and monitoring for diseases) and environmental approaches (greenhouse climate modification), a significant reduction in pathogen development and spread can be achieved. The use of preventive applications of microbial biological control agents and reduced-risk biorational products can also reduce disease development at all stages of production in jurisdictions where they are registered for use. The combined use of promising strategies for integrated disease management in cannabis plants during greenhouse production will be reviewed. Future areas for research are identified. Full article

For more than a century, Cannabis was considered a narcotic and has been banned by lawmakers all over the world. In recent years, interest in this plant has increased due to its therapeutic potential, in addition to a very interesting chemical composition, characterized by the presence of an atypical family of molecules known as phytocannabinoids. With this emerging interest, it is very important to take stock of what research has been conducted so far on the chemistry and biology of Cannabis sativa. The aim of this review is to describe the traditional uses, chemical composition and biological activities of different parts of this plant, as well as the molecular docking studies. Information was collected from electronic databases, namely SciFinder, ScienceDirect, PubMed and Web of Science. Cannabis is mainly popular for its recreational use, but it is also traditionally used as remedy for the treatment of several diseases, including diabetes, digestive, circulatory, genital, nervous, urinary, skin and respiratory diseases. These biological proprieties are mainly due to the presence of bioactive metabolites represented by more than 550 different molecules. Molecular docking simulations proved the presence of affinities between Cannabis compounds and several enzymes responsible for anti-inflammatory, antidiabetic, antiepileptic and anticancer activities. Several biological activities have been evaluated on the metabolites of Cannabis sativa, and these works have shown the presence of antioxidant, antibacterial, anticoagulant, antifungal, anti-aflatoxigenic, insecticidal, anti-inflammatory, anticancer, neuroprotective and dermocosmetic activities. This paper presents the up-to-date reported investigations and opens many reflections and further research perspectives. Full article

In this study, the allelochemical-induced effects of the leaf water extract of hemp (Cannabis sativa) on seed germination and seedling growth were investigated in durum wheat (Triticum durum) cv. Mongibello and barley (Hordeum vulgare) cv. Alamo. The seeds were imbibed in 25%, 50%, 75%, or 100% solution concentrations, obtained from a 2% hemp leaf extract, and they were germinated at 20 and 10 °C. The 2% extract stock solution (i.e., 100% solution concentration) was obtained by extracting 20 g of leaf powder in 1 L distilled water (2%, w/v). A control of seeds imbibed in distilled water was considered. Germination was scored daily and at the end of the germination test, the final germination percentage (FGP), mean germination time (MGT), germination index (GI), and vigor index (VI) were calculated. The radicles and shoots of the germinated seeds of both species were also measured for their length and weight. The analyses revealed the presence of phenols in the hemp leaf extract, which were the highest in the 100% concentration (13.14 ± 0.20 mg gallic acid equivalent-GAE g⁻¹ extract). At 20 °C, increasing the concentration had either minor (in wheat) or no effects (in barley) on the seed germination. At 10 °C, the germination was reduced by the increasing concentration, suggesting a potential allelopathic effect of the extract. However, at 100% concentration, the seeds germinated significantly better that those at 75% concentration. At 20 °C, increasing concentration progressively depressed both the radicle and shoot elongation in both species. At 10 °C, the radicle elongation was depressed by the extract, irrespective of the concentration, whilst the shoots were as long as those of the control in wheat, and smaller at the 50 and 75% concentrations in barley. We can conclude that the water extract of hemp leaves can have a negative impact on wheat and barley seed germination and seedling growth, particularly at temperatures below optimal. However, the high concentration of phenols in the extract may stimulate seed germination and seedling growth. Thus, in semi-arid areas, such as those of the Mediterranean regions, sowings of wheat and barley after hemp at an optimal (i.e., 20 °C) or nearly optimal temperature are recommended in order to minimize the combined stressing effects of the temperature and allelopathic leaf extract upon plant establishment, which may limit a successful crop establishment. Full article

This paper studies one of the most popular investment themes over recent years, investing in the cannabis industry. In particular, it investigates relationships between investor attention, as proxied by Google Trends, and stock market activities, i.e., return, volatility, and liquidity. To this end, in the empirical analysis we study how liquidity and investors’ attention affect the return dynamics of an investment in cannabis stocks by augmenting the three-factor Fama–French model. In addition, we use a vector autoregressive approach and the impulse response function to measure shock transmission between the variables under consideration. Our empirical findings show that there is a statistically positive relationship between cannabis stock returns and liquidity. We also find that increased investors’ attention results in higher returns. Full article

There is a growing interest in the production of hemp for the extraction of cannabidiol (CBD) due to reported therapeutic benefits. Recent policy reform has permitted state hemp pilot programs, including the land grant research institutions, the ability to investigate the potential of growing and harvesting Cannabis sativa plants (≤0.3% tetrahydrocannabinol) for these purposes in the U.S. There are vast gaps of knowledge regarding the fertility requirements of hemp cultivars grown in a horticultural production setting for floral attributes such as the cannabinoid constituents. Foliar tissue analysis provides an avenue to determine adequate ranges for nutrient uptake and estimating fertilizer requirements prior to visual symptoms of deficiency or toxicity. To facilitate a survey range of elemental nutrient acquisition in hemp cultivars propagated for CBD production, foliar analysis was executed using the most recently mature leaves (MRML) of mother stock plants. All plants were maintained in the vegetative stage for twelve weeks, prior to initiation of cutting for clone harvesting. A total of thirteen cultivars were utilized to broaden previously reported baseline survey ranges. Significant differences were found among all thirteen cultivars in accumulation of both micro and macro essential nutrients, widening the range of the fertility requirements of Cannabis plants grown in this production model for CBD harvesting. Full article