Hemp (Cannabis salvia L.) Cultivation: Chemical Fertilizers or Organic Technologies, a Comprehensive Review

Tzimas P.S., Beteinakis S., Petrakis E.A., Papastylianou P.T., Kakabouki I., Small-Howard A.L., Skaltsounis L.A., Halabalaki M.

The high value of fiber-type Cannabis sativa L. (hemp) due to its phytochemicals has yet to be fully recognized and leveraged. Besides cannabidiol (CBD), which is the most prevalent non-psychoactive cannabinoid, hemp contains numerous other cannabinoids with unexplored bioactivities, in addition to various compound classes. Previous works have aimed to correlate chemical profiles of C. sativa inflorescences with important parameters, mostly based on experiments under controlled conditions. However, mapping studies that explore the phytochemical diversity of hemp in a more realistic context are crucial to guide decisions at multiple levels, especially in areas where hemp cultivation was recently re-authorized, including Mediterranean countries. In this work, a powerful strategy was followed to map the phytochemical diversity of cultivated hemp in Greece, being the first study of its kind for this environment. A panel of 98 inflorescence samples, covering two harvesting years, eleven geographical regions and seven commonly used EU varieties, were studied using a combination of targeted and untargeted approaches. Quantitative results based on UPLC-PDA revealed relatively constant CBD/THC (total) ratios, while profiling by LC-HRMS effectively probed the phytochemical variability of samples, and led to the annotation of 88 metabolites, including a multitude of minor cannabinoids. Multivariate analysis substantiated a strong effect of harvesting year in sample discrimination and related biomarkers were revealed, belonging to fatty acids and flavonoids. The effect of geographical region and, especially, variety on chemical variation patterns was more intricate to interpret. The results of this work are envisioned to enhance our understanding of the real-world phytochemical complexity of C. sativa (hemp), with a view to maximized utilization of hemp for the promotion of human well-being.

Kaminski K.P., Hoeng J., Goffman F., Schlage W.K., Latino D.

The resurgence of cannabis (Cannabis sativa L.) has been propelled by changes in the legal framework governing its cultivation and use, increased demand for hemp-derived products, and studies recognizing the industrial and health benefits of hemp. This has led to the creation of novel high-cannabidiol, low-Δ9-tetrahydrocannabinol varieties, enabling hemp crop expansion worldwide. This review elucidates the recent implications for hemp cultivation in Europe, with a focus on the legislative impacts on the cultivation practices, prospective breeding efforts, and dynamic scientific landscape surrounding this crop. We also review the current cultivars’ cannabinoid composition of the European hemp market and its major differences with that of the United States.

Puttharak P., Wangnai P., Puttharak J., Baisaeng N.

This study explores the application of sustainable organic and biorefinery methods to increase the production of therapeutic hemp. Specifically, it focuses on Solodiol, Carmagnola, and Doctor Seedman strains. The study was carried out for 60 days in a highly controlled setting. It employed a unique combination of Murashige and Skoog (MS) media, supplemented with 2,4-D (0.5 mg/L) and kinetin (0.5 mg/L), and augmented with organic additions such as coconut water. This distinctive amalgamation facilitated extraordinary expansion across all varieties. The Solodiol strain demonstrated remarkable growth characteristics in terms of the number of branches, leaves, shoots, and height, whilst Carmagnola and Doctor Seedman indicated significant differences in diameter. Carmagnola, specifically, flourished in specific conditions: a strict 16-h period of light followed by 8 h of darkness, particularly when exposed to blue light. The Carmagnola strain, grown using MS feed (2StemMS), produced a hemp oil extract with a high concentration of 3.85%, compared to the Solodiol and Doctor Seedman strains, and also showcases their potential in promoting an environmentally friendly and therapeutically helpful medicinal hemp industry.

Podder S., Shafian S., Thomason W.E., Wilson T.B., Fike J.H.

Industrial hemp (Cannabis sativa L.) holds promise as a crop for more sustainable supply chains given its potential as a source of high-strength fibers, adsorbents, and nutrient-dense feedstuffs. Developing nutrient management guidelines for hemp will be an important part of optimizing the crop’s sustainability attributes. This study measured hemp seed yield in response to N fertilization rate (0, 60, 120, 180, and 240 kg N ha−1). Treatments were tested with four hemp cultivars (‘Joey’ and ‘Grandi’ in 2020, 2021, and 2022 and ‘NWG 2463’ and ‘NWG 4113’ in 2023) in Virginia. Nitrogen input influenced (p ≤ 0.0177) seed yield in all four experimental years, although the pattern of response varied substantially. In 2020, following delayed seeding, hemp showed a weak quadratic (p = 0.0113) response to N inputs, with peak yield (1640 kg ha−1) occurring with 120 kg N ha−1. In 2021, hemp displayed a strong linear (p < 0.0001) response to N inputs, with the highest seed yield (2510 kg ha−1) at 240 kg N ha−1. In 2022, a season characterized by low precipitation and high weed pressure, a weak, linear (p = 0.0111) response to the N rate was observed. The greatest seed yield (380 kg ha−1) was again observed with 240 kg N ha−1. In 2023, weed pressure remained an issue, but the response to N was strong and linear (p < 0.0001), with the greatest seed yield (831 kg ha−1) again measured at 240 kg N ha−1. These findings indicate hemp can be quite responsive to N inputs but that the magnitude of response is sensitive to other factors such as available soil moisture, weed pressure, and growing period.

Cahill M.S., Arsenault T., Bui T.H., Zuverza-Mena N., Bharadwaj A., Prapayotin-Riveros K., White J.C., Dimkpa C.O.

Kalousek P., Holátko J., Schreiber P., Pluháček T., Širůčková Lónová K., Radziemska M., Tarkowski P., Vyhnánek T., Hammerschmiedt T., Brtnický M.

Abstract Background Hemp (Cannabis sativa) is a crop with a wide range of uses, from the production of fiber and seeds to the secondary metabolites for medicinal purposes. In addition, it is characterized by high biomass yield and the ability to accumulate heavy metals, which makes this plant convenient for phytoremediation purposes. In this study, the effect of applying exogenous biodegradable chelating agents, citric acid (CA) and nitrilotriacetic acid (NTA), to zinc-contaminated soil on zinc (Zn) uptake by two industrial hemp varieties ‘Felina 32’ and ‘Monoica’ was studied. The effect of CA and NTA on available Zn in soils was investigated using an ‘in pot’ experiment under controlled conditions. The effect of both tested compounds on soil microbial activity was simultaneously evaluated. Results After the application of NTA at a concentration of 5 mmol L−1, a > threefold increased accumulation of Zn in the above-ground parts was recorded in the ‘Felina 32’ variety. In the ‘Monoica’ variety, the levels of Zn in the above-ground parts were increased > twofold. NTA affected the soil microbiome negatively, causing decreased enzyme activity (in ‘Monoica’ planted soil) and induced respiration (in ‘Monoica’ and especially in ‘Felina 32’ planted soil). On the other hand, CA application did not lead to significantly increased Zn levels in any of the studied hemp varieties. Together with CA’s negative effects on some soil enzymes, CA enhanced urease activity, dehydrogenase and several respiration types for the ‘Felina 32’ variety and exerted less detrimental effect on the soil microbiome. No toxic effects from increased Zn uptake and accumulation in experimental plants were detected, accounting for the unchanged physiological stress markers (levels of photosynthetic pigments and proline in leaves, chlorophyll fluorescence parameters) and selected growth traits of the above-ground organs and root system. Conclusions From the studied varieties, ‘Felina 32’ seems to be more suitable for Zn-phytoextraction because of its higher tolerance to increased Zn levels, higher biomass production and Zn accumulation capacity. Our results indicate the potential of using the ‘Felina 32’ variety in NTA-assisted Zn phytoextraction from contaminated soils. Graphical Abstract

Rizzo G., Storz M.A., Calapai G.

Recently, there has been a renewed interest in Cannabis sativa and its uses. The recreational use of inflorescences as a source of THC has led to the legal restriction of C. sativa cultivation to limit the detrimental effects of psychotropic substance abuse on health. However, this has also limited the cultivation of textile/industrial varieties with a low content of THC used for textile and nutritional purposes. While previously the bans had significantly penalized the cultivation of C. sativa, today many countries discriminate between recreational use (marijuana) and industrial and food use (hemp). The stalks of industrial hemp (low in psychotropic substances) have been used extensively for textile purposes while the seeds are nutritionally versatile. From hemp seeds, it is possible to obtain flours applicable in the bakery sector, oils rich in essential fatty acids, proteins with a high biological value and derivatives for fortification, supplementation and nutraceutical purposes. Hemp seed properties seem relevant for vegetarian diets, due to their high nutritional value and underestimated employment in the food sector. Hemp seed and their derivatives are a valuable source of protein, essential fatty acids and minerals that could provide additional benefit to vegetarian nutrition. This document aims to explore the information available in the literature about hemp seeds from a nutritional point of view, highlighting possible beneficial effects for humans with particular attention to vegetarian nutrition as a supplemental option for a well-planned diet.

Massuela D.C., Munz S., Hartung J., Nkebiwe P.M., Graeff-Hönninger S.

Indoor medicinal cannabis cultivation systems enable year-round cultivation and better control of growing factors, however, such systems are energy and resource intensive. Nutrient deprivation during flowering can trigger nutrient translocation and modulate the production of cannabinoids, which might increase agronomic nutrient use efficiency, and thus, a more sustainable use of fertilizers. This experiment compares two fertilizer types (mineral and organic) applied in three dilutions (80, 160 and 240 mg N L−1) to evaluate the effect of nutrient deprivation during flowering on biomass, Cannabidiol (CBD) yield and nutrient use efficiency of N, P and K. This is the first study showing the potential to reduce fertilizer input while maintaining CBD yield of medicinal cannabis. Under nutrient stress, inflorescence yield was significantly lower at the final harvest, however, this was compensated by a higher CBD concentration, resulting in 95% of CBD yield using one-third less fertilizer. The higher nutrient use efficiency of N, P, and K in nutrient-deprived plants was achieved by a larger mobilization and translocation of nutrients increasing the utilization efficiency of acquired nutrients. The agronomic nutrient use efficiency of CBD yield – for N and K – increased 34% for the organic fertilizers and 72% for the mineral fertilizers comparing the dilution with one-third less nutrients (160) with the highest nutrient concentration (240). Differences in CBD yield between fertilizer types occurred only at the final harvest indicating limitations in nutrient uptake due to nutrient forms in the organic fertilizer. Our results showed a lower acquisition and utilization efficiency for the organic fertilizer, proposing the necessity to improve either the timing of bio-availability of organic fertilizers or the use of soil amendments.

Sieracka D., Frankowski J., Wacławek S., Czekała W.

Hemp cultivation is becoming increasingly common worldwide, although it still raises many concerns. These plants are gaining popularity due to their versatility and the ability to use virtually every part of them in almost all economic branches. Hemp products are sought after and appreciated by consumers. The cultivation of hemp does not place a large burden on the environment. All this makes hemp an ideal plant in terms of land use, which is closely related to the idea of sustainable development. This paper describes the legal aspects of hemp cultivation in Europe and briefly presents its breeding and cultivation. The possibilities of their versatile use are presented, with particular reference to biofuel production. Moreover, the suitability for ecological cultivation, description of the economic and social aspects of industrial hemp cultivation, as well as future outlooks, are also described.

Morad D., Bernstein N.

Recent studies demonstrated a significant impact of some major macronutrients on function and production of medical cannabis plants, yet information on the effect of most nutrients, including Mg, is scarce. Magnesium is required for major physiological functions and metabolic processes in plants, and in the present study we studied the effects of five Mg treatments (2, 20, 35, 70, and 140 mg L−1 Mg), on plant development and function, and distribution of minerals in drug-type (medical) cannabis plants, at the vegetative growth phase. The plants were cultivated in pots under controlled environment conditions. The results demonstrate that plant development is optimal under Mg supply of 35–70 mg L−1 (ppm), and impaired under lower Mg input of 2–20 mg L−1. Two mg L−1 Mg resulted in visual deficiency symptoms, shorter plants, reduced photosynthesis rate, transpiration rate, photosynthetic pigments and stomatal conduction in young-mature leaves, and a 28% reduction of total plant biomass compared to the optimal supply of 35 mg L−1 Mg. The highest supply level of 140 mg L−1 Mg induced a small decrease in physiological function, which did not affect morphological development and biomass accumulation. The low-deficient Mg supply of 2 mg L−1 Mg stimulated Mg uptake and accumulation of N, P, K, Ca, Mn, and Zn in the plant. Increased Mg supply impaired uptake of Ca and K and their root-to-shoot translocation, demonstrating competitive cation inhibition. Mg-deficiency symptoms developed first in old leaves (at 2 mg L−1 Mg) and progressed towards young-mature leaves, demonstrating ability for Mg in-planta storage and remobilization. Mg toxicity symptoms appeared in old leaves from the bottom of the plants, under 140 mg L−1 Mg. Taken together, the findings suggest 35–70 mg L−1 Mg as the optimal concentration range for cannabis plant development and function at the vegetative growth phase.

Judžentienė A., Garjonytė R., Būdienė J.

The phytochemistry of fibre hemp (Cannabis sativa L., cv. Futura 75 and Felina 32) cultivated in Lithuania was investigated. The soil characteristics (conductivity, pH and major elements) of the cultivation field were determined. The chemical composition of hemp extracts and essential oils (EOs) from different plant parts was determined by the HPLC/DAD/TOF and GC/MS techniques. Among the major constituents, β-caryophyllene (≤46.64%) and its oxide (≤14.53%), α-pinene (≤20.25%) or α-humulene (≤11.48) were determined in EOs. Cannabidiol (CBD) was a predominant compound (≤64.56%) among the volatile constituents of the methanolic extracts of hemp leaves and inflorescences. Appreciable quantities of 2-monolinolein (11.31%), methyl eicosatetraenoate (9.70%) and γ-sitosterol (8.99%) were detected in hemp seed extracts. The octadecenyl ester of hexadecenoic acid (≤31.27%), friedelan-3-one (≤21.49%), dihydrobenzofuran (≤17.07%) and γ-sitosterol (14.03%) were major constituents of the methanolic extracts of hemp roots, collected during various growth stages. The CBD quantity was the highest in hemp flower extracts in pentane (32.73%). The amounts of cannabidiolic acid (CBDA) were up to 24.21% in hemp leaf extracts. The total content of tetrahydrocannabinol (THC) isomers was the highest in hemp flower pentane extracts (≤22.43%). The total phenolic content (TPC) varied from 187.9 to 924.7 (average means, mg/L of gallic acid equivalent (GAE)) in aqueous unshelled hemp seed and flower extracts, respectively. The TPC was determined to be up to 321.0 (mg/L GAE) in root extracts. The antioxidant activity (AA) of hemp extracts and Eos was tested by the spectrophotometric DPPH● scavenging activity method. The highest AA was recorded for hemp leaf EOs (from 15.034 to 35.036 mmol/L, TROLOX equivalent). In the case of roots, the highest AA (1.556 mmol/L, TROLOX) was found in the extracts of roots collected at the seed maturation stage. The electrochemical (cyclic and square wave voltammetry) assays correlated with the TPC. The hydrogen-peroxide-scavenging activity of extracts was independent of the TPC.

Frankowski J., Przybylska-Balcerek A., Graczyk M., Niedziela G., Sieracka D., Stuper-Szablewska K.

The popularity of hemp cultivation for industrial purposes has been steadily growing for many years. With the addition of products derived from these plants to the Novel Food Catalogue, maintained by the European Commission, a significant increase in interest in hemp food is also expected. The aim of the study was to determine the characteristics of hempseed, oil, and oil cake samples produced from experimental plots grown in different conditions. The research was conducted on the Henola variety, one of the newest and most popular varieties of hemp, recently bred for grain and oil. The content of bioactive compounds in grain and oil has been subjected to detailed chemical analyses in order to determine the effect of fertilization, the method of plant cultivation, and processing conditions on their quantity. The test results and the statistical analysis carried out showed a significant impact of the tested factors on the content of some of the tested bioactive compounds. The obtained results will help in the development of an effective method of cultivation for this hemp variety in order to maximize the content of the desired bioactive compounds per unit of cultivation area.

Fordjour E., Manful C.F., Sey A.A., Javed R., Pham T.H., Thomas R., Cheema M.

Cannabis sativa, also known as “hemp” or “weed,” is a versatile plant with various uses in medicine, agriculture, food, and cosmetics. This review attempts to evaluate the available literature on the ecology, chemical composition, phytochemistry, pharmacology, traditional uses, industrial uses, and toxicology of Cannabis sativa. So far, 566 chemical compounds have been isolated from Cannabis, including 125 cannabinoids and 198 non-cannabinoids. The psychoactive and physiologically active part of the plant is a cannabinoid, mostly found in the flowers, but also present in smaller amounts in the leaves, stems, and seeds. Of all phytochemicals, terpenes form the largest composition in the plant. Pharmacological evidence reveals that the plants contain cannabinoids which exhibit potential as antioxidants, antibacterial agents, anticancer agents, and anti-inflammatory agents. Furthermore, the compounds in the plants have reported applications in the food and cosmetic industries. Significantly, Cannabis cultivation has a minimal negative impact on the environment in terms of cultivation. Most of the studies focused on the chemical make-up, phytochemistry, and pharmacological effects, but not much is known about the toxic effects. Overall, the Cannabis plant has enormous potential for biological and industrial uses, as well as traditional and other medicinal uses. However, further research is necessary to fully understand and explore the uses and beneficial properties of Cannabis sativa.

Kaur N., Brym Z., Oyola L.A., Sharma L.K.

AbstractRegained interest in hemp cultivation has created opportunities and challenges, especially regarding crop management, for example, fertilizer application rate. Most of the literature on nitrogen (N) management in hemp production is from Asia and Europe, with more established cropping systems than in North America. Through our review, we found evidence that N fertilizer has a noticeable positive impact on basic crop morphology and physiology parameters, or at least the crop responds to such infield fertilizer applications. Some physiological parameters that show positive response include photosynthetic pigments, N and nitrate concentration, and water use efficiency. N fertilizer has been demonstrated to increase stem and fiber yield but reduce fiber quality. Increasing N also appears to increase seed yield and protein content. Both excess and low rates of N fertilizer are detrimental to floral hemp. There is little evidence that Δ9‐tetrahydrocannabinol concentration is more affected by N fertilization than genetics. The impact of fertilizer source and timing remains a critical area for research. There is still a need for research on developing a sustainable nutrient management program for hemp.

Blandinières H., Croci M., Impollonia G., Marcone A., Gay A., Winters A., Palmer S., Amaducci S.

Yellow stalked cultivars of hemp (Cannabis sativa L.) were reported to have a superior fibre processability than green cultivars, but the effects of the yellow trait on productivity and ecophysiology of hemp remain unexplored. It is hypothesised that yellow stalked cultivars are characterised by a low Nitrogen Uptake Efficiency. Three field scale experiments involving a yellow cultivar ('Fibror 79') and a green one ('Futura 75') grown under varying levels of nitrogen fertilisation were conducted in Northern Italy and in Wales, to investigate the effects of the yellow trait on hemp productivity and eco-physiology. The results showed that 'Fibror 79' displays a slightly lower biomass productivity than 'Futura 75' under nitrogen-limiting conditions, owing to lower Leaf Area Index and light interception capacity during the early growth phase, and potentially due to a lower radiation use efficiency. However, the productivity was not significantly different between cultivars under non-limiting nitrogen conditions. The Nitrogen Uptake Efficiency did not differ between the two cultivars, which failed to support the hypothesis of this work. Instead, Nitrogen Use Efficiency and Nitrogen Utilisation Efficiency were significantly higher for 'Futura 75' than for 'Fibror 79' under nitrogen-limiting conditions. 'Futura 75' appeared better suited than 'Fibror 79' for dual- and multi-purpose production in Italy, while the reverse was true in Wales. 'Fibror 79' better suits a strategy of single-use fibre production owing to its higher bast fibre content and fibre yield.

Zaman Q.U., Guo L., He X., Luo Y., Liu C., Murtaza G., Sultan K., Fahad S., Cheng X., Ashraf K., Deng G.

Hanc A., Dume B., Kusnierova S., Hrcka M., Hrebeckova T., Michal P., Hleibieh M., Nehasilova A., Cajthaml T.

The use of some organic fertilizers may raise concerns about the transfer of hazardous substances to soil and plants. This study examined the impact of soil amendment with compost and vermicompost derived from sewage sludge and straw pellets in different ratios on the accumulation of pharmaceuticals and personal care products (PPCPs) by hemp (Cannabis sativa L.). The concentrations of fifty different PPCPs were measured in compost-treated soil, and in the roots and above-ground biomass of cannabis grown on the soil. The highest bioaccumulation of PPCPs was recorded in plants from previously unfertilized soils low in organic matter, while the lowest concentrations were measured in soil amended with compost or vermicompost made from straw pellets only, without sewage sludge. The effect of sludge-derived compost and vermicompost application on the absorption of PPCPs was statistically determined by measurements in soil samples, roots and shoots of carbamazepine, cetirizine, lamotrigine, telmisartan, paraxanthine, tramadol, triclosan, and venlafaxine. The above-ground biomass exhibited lower PPCP content than roots, suggesting a potential plant defense mechanism for limiting contaminant translocation. Only tramadol and carbamazepine showed significantly increased content in above-ground biomass.

Varga I., Markulj Kulundžić A., Krolo P., Iljkić D., Tišma M., Kraus I.

The growing interest in Cannabis sativa as a highly used crop is present worldwide. There are limited data about the effect of potassium (K) fertilizer on industrial hemp yield for dual purposes (seed and stem production). The current study aimed to investigate the influence of adding two different K fertilizers, KCl and K2SO4, at two growth stages (flowering and ripening) on the productivity and chlorophyll a fluorescence (ChlF) of Cannabis sativa, variety Finola. Before sowing, different K treatments were applied: K1—100 kg ha−1 KCl (60% K) and K2—100 kg ha−1 K2SO4 (52% K, S 17%). The OJIP (O stands for “origin” (minimal fluorescence), P for “peak” (maximum fluorescence), and J and I for inflection points between the O and P levels) data were recorded and used for ChlF transients and individual ChlF parameters during vegetation. At harvest, the stem morphology parameters and yield (plant height, stem weight and diameter, and stem and seed yield), tensile strength, and the modulus of elasticity were determined. The results show the sensitivity of minimal (F0) and maximal fluorescence (Fm), electron transport from QA to intersystem electron acceptors (ET0/(TR0 − ET0)), and electron transport flux until PSI acceptors (RE0/RC) to K fertilization. The parameters that described electron transport (ET0/RC, ψE0, and φE0), performance index on absorption basis (PIABS, TR0/DI0, and φP0), dissipation (DI0/RC), and electron transport to photosystem I (φR0 and δR0/(1 − δR0)) had a reaction only at the growth stage, indicating a change in their activity during the aging of the Cannabis sativa plants. The average stem height was 67.5 cm, and the stem diameter was 0.41 cm. The different K sources did not significantly influence the stem height and diameter, nor the dry stem (on average 12.2 t ha−1) and seed yield (on average 1.85 t ha−1). The tensile strength of individual hemp stems was the highest with K2SO4 (53.32 MPa) and the lowest with KCl (49.25 MPa). The stem stiffness by modulus of elasticity was about 5 GPa on average for all the treatments. In general, the photosynthetic parameters in this study varied more between the growth stages than between the different K fertilizer formulations. Moreover, based on the results of this study, it can be recommended to use both fertilizers, KCl and K2SO4, in dual-purpose industrial hemp production since no significant effect was found for the stem morphometric and biomechanical parameters as well as for the agronomic parameters.

Ahsan S.M., Injamum-Ul-Hoque M., Das A.K., Imran M., Tavakoli S., Kwon D.B., Kang S., Lee I., Choi H.W.

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.