Response of Medical Cannabis to Magnesium (Mg) Supply at the Vegetative Growth Phase

Song C., Saloner A., Fait A., Bernstein N.

The primary and secondary metabolism of plants is closely connected to the resources supplied and obtained by the plant, including their mineral nutrition. We recently reported that nitrogen (N) deficiency enhances the production of terpenoids and cannabinoids, the unique biologically-active secondary metabolites in medical cannabis plants. Knowledge-gaps concerning effects of N supply on primary metabolism in cannabis hinder understanding of the interrelations between N inputs and biosynthesis of the therapeutic secondary metabolites. The present study therefore evaluated the hypothesis that a decrease in the plant’s C (carbon): N ratio by N-limitation, induces a shift in the plant metabolism towards lower production of N-containing metabolites and higher production of metabolites that do not contain N. Effects of N input levels (30, 80, 160, 240, and 320 mg L−1) on total C and N concentrations and C: N ratio in leaves and inflorescences of medical cannabis plants were studied; and gas chromatography-mass spectrometry (GC-MS) analysis of primary metabolites added to the analyses of secondary metabolites. Elevation of N supply resulted in an increase in total N and N-containing compounds (chlorophylls and most amino acids), and decreased total C and compounds that do not contain N, such as sugars (fructose, glucose, and xylose), and phosphates (phosphate and glucose-6-phosphate) in both inflorescences and leaves. In the inflorescences, the elevation of N input also decreased total cannabinoids, phenols, and flavonoids, that do not contain N. Integrating the metabolic datasets revealed positive correlations between C sources (fructose and glucose) and most of the cannabinoids and terpenoids; the latter were negatively correlated with N-compounds (most amino acids). Taken together, these results suggest that elevated N supply induce a metabolic shift in the inflorescences towards increased production of N-compounds via deflecting the C sources from the biologically active compounds. In addition, the cannabis leaf was found to be more sensitive than the inflorescence to N supply, presenting greater changes in primary metabolism and more coordinated metabolic associations. These findings highlight the importance of adequate and precise N nutrition for standardization of the therapeutic-metabolite profile and for preventing undesirable metabolic repartitioning in medical cannabis plants.

Westmoreland F.M., Bugbee B.

Phosphorus (P) is an essential but often over-applied nutrient in agricultural systems. Because of its detrimental environmental effects, P fertilization is well studied in crop production. Controlled environment agriculture allows for precise control of root-zone P and has the potential to improve sustainability over field agriculture. Medical Cannabis is uniquely cultivated for the unfertilized female inflorescence and mineral nutrition can affect the yield and chemical composition of these flowers. P typically accumulates in seeds, but its partitioning in unfertilized Cannabis flowers is not well studied. Here we report the effect of increasing P (25, 50, and 75 mg P per L) in continuous liquid fertilizer on flower yield, cannabinoid concentration, leachate P, nutrient partitioning, and phosphorus use efficiency (PUE) of a high-CBD Cannabis variety. There was no significant effect of P concentration on flower yield or cannabinoid concentration, but there were significant differences in leachate P, nutrient partitioning, and PUE. Leachate P increased 12-fold in response to the 3-fold increase in P input. The P concentration in the unfertilized flowers increased to more than 1%, but this did not increase yield or quality. The fraction of P in the flowers increased from 25 to 65% and PUE increased from 31 to 80% as the as the P input decreased from 75 to 25 mg per L. Avoiding excessive P fertilization can decrease the environmental impact of Cannabis cultivation.

Inoue S., Hayashi M., Huang S., Yokosho K., Gotoh E., Ikematsu S., Okumura M., Suzuki T., Kamura T., Kinoshita T., Ma J.F.

Plant stomata play an important role in CO2 uptake for photosynthesis and transpiration, but the mechanisms underlying stomatal opening and closing under changing environmental conditions are still not completely understood. Through large-scale genetic screening, we isolated an Arabidopsis mutant (closed stomata2 (cst2)) that is defective in stomatal opening. We cloned the causal gene (MGR1/CST2) and functionally characterized this gene. The mutant phenotype was caused by a mutation in a gene encoding an unknown protein with similarities to the human magnesium (Mg2+ ) efflux transporter ACDP/CNNM. MGR1/CST2 was localized to the tonoplast and showed transport activity for Mg2+ . This protein was constitutively and highly expressed in guard cells. Knockout of this gene resulted in stomatal closing, decreased photosynthesis and growth retardation, especially under high Mg2+ conditions, while overexpression of this gene increased stomatal opening and tolerance to high Mg2+ concentrations. Furthermore, guard cell-specific expression of MGR1/CST2 in the mutant partially restored its stomatal opening. Our results indicate that MGR1/CST2 expression in the leaf guard cells plays an important role in maintaining cytosolic Mg2+ concentrations through sequestering Mg2+ into vacuoles, which is required for stomatal opening, especially under high Mg2+ conditions.

Saloner A., Bernstein N.

The N form supplied to the plant, ammonium (NH4+) or nitrate (NO3–), is a major factor determining the impact of N nutrition on plant function and metabolic responses. We have hypothesized that the ratio of NH4/NO3 supplied to cannabis plants affects the physiological function and the biosynthesis of cannabinoids and terpenoids, which are major factors in the cannabis industry. To evaluate the hypothesis we examined the impact of five supply ratios of NH4/NO3 (0, 10, 30, 50, and 100% N-NH4+, under a uniform level of 200 mg L–1 N) on plant response. The plants were grown in pots, under controlled environment conditions. The results revealed high sensitivity of cannabinoid and terpenoid concentrations and plant function to NH4/NO3 ratio, thus supporting the hypothesis. The increase in NH4 supply generally caused an adverse response: Secondary metabolite production, inflorescence yield, plant height, inflorescence length, transpiration and photosynthesis rates, stomatal conductance, and chlorophyll content, were highest under NO3 nutrition when no NH4 was supplied. Ratios of 10–30% NH4 did not substantially impair secondary metabolism and plant function, but produced smaller inflorescences and lower inflorescence yield compared with only NO3 nutrition. Under a level of 50% NH4, the plants demonstrated toxicity symptoms, which appeared only at late stages of plant maturation, and 100% NH4 induced substantial plant damage, resulting in plant death. This study demonstrates a dramatic impact of N form on cannabis plant function and production, with a 46% decrease in inflorescence yield with the increase in NH4 supply from 0 to 50%. Yet, moderate levels of 10–30% NH4 are suitable for medical cannabis cultivation, as they do not damage plant function and show only little adverse influence on yield and cannabinoid production. Higher NH4/NO3 ratios, containing above 30% NH4, are not recommended since they increase the potential for a severe and fatal NH4 toxicity damage.

Saloner A., Bernstein N.

We have demonstrated in previous studies that the essential macro-nutrients nitrogen (N) and phosporous (P) have profound effects on the production of cannabinoids and terpenoids in the cannabis plant. The present study was undertaken to evaluate the hypothesis that potassium (K) supply, which is known to substantially affect plant development and function, affects the secondary metabolism of the cannabis plant. Two cultivars of medical cannabis were grown in controlled environment conditions, under five levels of K supply: 15, 60, 100, 175, and 240 mg L−1 K. The results revealed that the development and function of plants that received the low K supply of 15 mg L−1 K were impaired, as the plants suffered from visual chlorosis, and the inflorescence yield was reduced in both cultivars. Plants that received higher K inputs in the range of −175 mg L−1 K demonstrated optimal plant function and high yield, and one cultivar demonstrated over-supply symptoms under the high K level of 240 mg L−1. The concentrations of most cannabinoids and terpenoids declined with the elevation of K supply, thus supporting the hypothesis. As secondary metabolite concentrations decreased with the increase in K supply, and higher K levels had no positive effects, 60 mg L−1 K is the suggested application level to maintain high function and yield combined with high secondary metabolism.

Bevan L., Jones M., Zheng Y.

Following legalisation, cannabis has quickly become an important horticultural crop in Canada and increasingly so in other parts of the world. However, due to previous legal restrictions on cannabis research there are limited scientific data on the relationship between nitrogen (N), phosphorus (P), and potassium (K) supply (collectively: NPK) and the crop yield and quality. This study examined the response of a high delta-9-tetrahydrocannabinol (THC) Cannabis sativa cultivar grown in deep-water culture with different nutrient solution treatments varying in their concentrations (mg L–1) of N (70, 120, 180, 250, 290), P (20, 40, 60, 80, 100), and K (60, 120, 200, 280, 340) according to a central composite design. Results demonstrated that inflorescence yield responded quadratically to N and P, with the optimal concentrations predicted to be 194 and 59 mg L–1, respectively. Inflorescence yield did not respond to K in the tested range. These results can provide guidance to cultivators when formulating nutrient solutions for soilless cannabis production and demonstrates the utility of surface response design for efficient multi-nutrient optimisation.

Tian X., He D., Bai S., Zeng W., Wang Z., Wang M., Wu L., Chen Z.

Mg is a macronutrient for plant growth. Mg deficiency has become an important limiting factor in intensive agricultural production, resulting in reduced crop yield and quality. Given that Mg is also essential for human and animals’ diets, Mg nutrition in plants has become an important issue not only for food security but also for human health. We review recent progress in physiological and molecular mechanisms underlying Mg biological functionality, as well as Mg transport and Mg deficiency symptoms in plants. As both a structural component and a regulatory factor, Mg helps plants achieve higher photosynthetic efficiency, nitrogen use efficiency and stress resistance. Plants need a certain range of Mg concentration for their growth, and a number of key genes responsible for Mg uptake, translocation and detoxification have been identified. Despite its functional importance, basic researches on Mg nutrition are still scarce. A deeper investigation of the genetic and molecular mechanisms employed in Mg nutrition will help to improve crop yield and intensify Mg application in the field. Developing more approaches to enhance Mg concentration in crop edible parts is urgently required for human diet and health.

Saloner A., Bernstein N.

• N Supply affects cannabinoid and terpenoid concentrations in medical cannabis. • Tetrahydrocannabinolic acid and cannabidiolic acid decrease with the increase in N application. • Inflorescence yield is highest under 160–320 mg L −1 N. • Growth retardation and visual chlorosis are induced by N supply lower than 160 mg L −1 N, and N supply up to 320 mg L −1 did not induce a toxicity response. • The optimal N level for yield quantity, combined with relatively high secondary metabolite content, is 160 mg L −1 N. Secondary metabolism in plants is considerably affected by environmental factors including mineral nutrition. Nitrogen is a key plant nutrient, known to affect primary and secondary metabolism in plants, that its effect on the cannabis plants' chemical profile is not known. To evaluate the hypothesis that N supply affects the cannabinoid and terpenoid profile, we studied the impact of N application on chemical and functional-physiology phenotyping in medical cannabis at the flowering stage. The plants were grown under five N treatments of 30, 80, 160, 240, and 320 mg L −1 (ppm) under environmentally controlled conditions. The results revealed that N supply affects cannabinoid and terpenoid metabolism, supporting the hypothesis. The concentrations of most cannabinoids and terpenoids tested were highest under the deficient concentration of 30 mg L −1 N and declined with the elevation of N supply. The concentrations of the two main cannabinoids, tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA), decreased by 69% and 63%, respectively, with the increase in N supply from 30 to 320 mg L −1 N. Plant development and function were restricted under inputs lower than 160 mg L −1 N, demonstrating N deficiency. The morpho-physiological state of the plants was optimal at supply rates of 160–320 mg L −1 N. Inflorescence yield reflected the plant physiological state, increasing with the increase in N supply up to 160 mg L −1 N, and was unaffected by further increase in N. These results of the functional and chemical characterizations suggest that high N supply has adverse effects on the production of secondary compounds in cannabis, while it promotes growth and biomass production. Hence, N supply may serve for the regulation of the cannabinoid and terpenoid profiles, or for increasing plant yield, according to the desired production scheme. Taken together, the results reveal that the optimal N level for yield quantity, that allows also a relatively high secondary metabolites content, is 160 mg L −1 N. Finally, the present study provides a better understanding of the impact of N on 'drug-type' medical cannabis physiology, and takes us one step closer to the optimization of medical cannabis cultivation.

He H., Khan S., Deng Y., Jin X., Ma H., Li X., Yin L., Huang J.

This study aimed to evaluate the biochemical impact of magnesium (Mg) deficiency on banana cultivars. Seedlings of three banana cultivars, Baxi (Musa, AAA), Haigong (Musa, AA), and Guangfen no.1 (Musa, ABB), with five expanded leaves were sand cultured with nutrient solution containing 10 µM (Mg-deficient) and 1000 µM of MgSO4. After 12 weeks of Mg deficiency, Mg content in leaves and plant dry biomass was significantly reduced. The superoxide dismutase activity was increased in all three cultivars, while the photosynthesis seems to be unaffected. Differential responses were observed in different cultivars under Mg deficiency, and deficiency symptoms appeared on the leaves of Baxi and Haigong, while no symptoms appeared on Guangfen no. 1. Similarly, the increase in potassium, calcium, sucrose, starch contents and higher lipid peroxidation under Mg deficiency was observed in Baxi and Haigong, while unaffected in Guangfen no. 1. Also, antioxidant enzyme activity of ascorbate peroxidase and glutathione reductase was significantly increased in Haigong and Baxi, respectively. Mg deficiency reduced the biomass and root and shoot dry weight ratio, accompanied by the accumulation of malondialdehyde, sucrose, and starch content. The genetic differences are responsible for the tolerance of Mg deficiency in banana seedlings.

Shiponi S., Bernstein N.

Environmental conditions, including the availability of mineral nutrients, affect secondary metabolism in plants. Therefore, growing conditions have significant pharmaceutical and economic importance for Cannabis sativa. Phosphorous is an essential macronutrient that affects central biosynthesis pathways. In this study, we evaluated the hypothesis that P uptake, distribution and availability in the plant affect the biosynthesis of cannabinoids. Two genotypes of medical “drug-type” cannabis plants were grown under five P concentrations of 5, 15, 30, 60, and 90 mg L–1 (ppm) in controlled environmental conditions. The results reveal several dose-dependent effects of P nutrition on the cannabinoid profile of both genotypes, as well as on the ionome and plant functional physiology, thus supporting the hypothesis: (i) P concentrations ≤15 mg L–1 were insufficient to support optimal plant function and reduced photosynthesis, transpiration, stomatal conductance and growth; (ii) 30–90 mg L–1 P was within the optimal range for plant development and function, and 30 mg L–1 P was sufficient for producing 80% of the maximum yield; (iii) Ionome: about 80% of the plant P accumulated in the unfertilized inflorescences; (iv) Cannabinoids: P supply higher than 5 mg L–1 reduced Δ9-tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA) concentrations in the inflorescences by up to 25%. Cannabinoid concentrations decreased linearly with increasing yield, consistent with a yield dilution effect, but the total cannabinoid content per plant increased with increasing P supply. These results reveal contrasting trends for effects of P supply on cannabinoid concentrations that were highest under <30 mg L–1 P, vs. inflorescence biomass that was highest under 30–90 mg L–1 P. Thus, the P regime should be adjusted to reflect production goals. The results demonstrate the potential of mineral nutrition to regulate cannabinoid metabolism and optimize pharmacological quality.

Weih M., Liu H., Colombi T., Keller T., Jäck O., Vallenback P., Westerbergh A.

Modern crop production is characterized by high nitrogen (N) application rates, which can influence the co-limitation of harvested yield by other nutrients. Using a multidimensional niche volume concept and scaling exponents frequently applied in plant ecological research, we report that increased N and phosphorus (P) uptake in a growing wheat crop along with enhanced grain biomass is associated with more than proportional increase of other nutrients. Furthermore, N conversion efficiency and grain yield are strongly affected by the magnesium (Mg) to P ratio in the growing crop. We analyzed a field trial in Central Sweden including nine wheat varieties grown during two years with contrasting weather, and found evidence for Mg co-limitation at lower grain yields and P co-limitation at higher yields. We argue that critical concentrations of single nutrients, which are often applied in agronomy, should be replaced by nutrient ratios. In addition, links between plant P and Mg contents and root traits were found; high root number enhanced the P:N ratio, whilst steep root angle, indicating deep roots, increased the Mg:N ratio. The results have significant implications on the management and breeding targets of agriculturally grown wheat, which is one of the most important food crops worldwide.

Xie K., Cakmak I., Wang S., Zhang F., Guo S.

Magnesium (Mg) affects various critical physiological and biochemical processes in higher plants, and its deficiency impedes plant growth and development. Although potassium (K)-induced Mg deficiency in agricultural production is widespread, the specific relationship of K with Mg and especially its competitive nature is poorly understood. This review summarizes current knowledge on the interactions between K and Mg with respect to their root uptake, root-to-shoot translocation and distribution in plants. Their synergistic effects on certain physiological functions are also described. The antagonistic effect of K on Mg is stronger than that of Mg on K in root absorption and transport within plants, indicating that the balanced use of K and Mg fertilizers is necessary for sustaining high plant-available Mg and alleviating K-induced Mg deficiency, especially in plant species with high K demand or in high-available-K soil. The relationship between Mg and K in plant tissues may be antagonistic or synergistic depending on plant species, cell type, leaf age, source- and sink organs. There are synergistic effects of K and Mg on photosynthesis, carbohydrate transport and allocation, nitrogen metabolism, and turgor regulation. Definition of optimal K/Mg ratios for soils and plant tissues is desirable for maintaining proper nutritional status in plants, leading to a physiological state supporting crop production. Future research should concentrate on identifying the physiological and molecular mechanisms underlying the interactions between K and Mg in a given physiological function.

Shiponi S., Bernstein N.

Phosphorus (P) is an essential macronutrient required for many central metabolic processes, and is therefore a major factor governing plant development, structure and function. Cannabis is a short-day plant that its' development progression involves a vegetative growth phase under long photoperiod, followed by a reproductive phase under a short photoperiod. The reproductive inflorescence yield potential in cannabis is therefore largely dependent on the morphology and physiological condition of the plants at the vegetative phase. Due to legal restrictions, there is lack of science-based knowledge about cannabis plant science, including mineral nutrition. The present study therefore focused on P nutrition of plants at the vegetative growth phase under long photoperiod. The plants were cultivated in pots in a controlled environment and subjected to 5 levels of P (5, 15, 30, 60, 90 mg L−1). We investigated impact on the ionome, physiological and morphological traits, uptake of nutrients into the plant, translocation to the shoot, and distribution in the plant organs for 2 medicinal cannabis genotypes. Plant biomass production, photosynthesis rate, stomatal conductance, transpiration rate and intercellular CO2 at the vegetative growth phase exceled under 30 mg L−1 P supply. Uptake and translocation of nutrients from root to the shoot was highly influenced by the P treatment. Under excess P supply, most of the plant P accumulated in the roots, and translocation to the shoot was inhibited. Uptake of Mg into the plants, and its' translocation to the shoot was inhibited by P deficiency in both cultivars, and was enhanced by increased P supply. Calcium uptake was increased by P application but translocation to the shoot was inhibited. Zinc retention in roots under P deficiency was found in both varieties. Our results suggest a wide optimum range for P in medicinal cannabis at the vegetative growth stage, with a minimum requirement of 15 mg L−1 P and a recommended application of 30 mg L−1. The functional physiology and ionome profiling revealed genotypic variability in P sensitivity.

Saloner A., Bernstein N.

The development progression of medical cannabis plants includes a vegetative growth phase under long photoperiod, followed by a reproductive phase under short photoperiod. Establishment of plant architecture at the vegetative phase therefore affects its reproduction potential under short photoperiod. Nitrogen (N) is a main component of many metabolites that involve in central processes in plants, and is therefore a major factor governing plant development and structure. We lack information about the influence of N nutrition on medical cannabis functional-physiology and development, and plant N requirements are yet unknown. The present study therefore investigated the developmental, physiological and chemical responses of medical cannabis plants to N supply (30, 80, 160, 240 and 320 mgL-1 N) under long photoperiod. We report that the morpho-physiological function under long photoperiod in medical cannabis is optimal at 160 mgL-1 N supply, and significantly lower under 30 mgL-1 N, with visual deficiency symptoms, and 75% and 25% reduction in plant biomass and photosynthesis rate, respectively. Nitrogen use efficiency decreased with the increase in N supply, while osmotic potential, water use efficiency, photosynthetic pigments and total N and N-NO3 concentrations in plant tissues increased with N supply. The plant ionome was considerably affected by N supply. Concentrations of K, P, Ca, Mg, Na and Fe in the plant were highest under the optimal N level of 160 mgL-1 N, with differences between organs in the extent of accumulation. The majority of the nutrients tested, including P, S, Zn, Mn, Fe and Cu tented to accumulate in the roots >leaves>stem, while K and Na tented to accumulate in the stem>leaves> roots, and total N, Ca and Mg accumulated in leaves>roots>stem. Taken together, the results demonstrate that the optimal N level for plant development and function at the vegetative growth phase is 160 mgL-1 N. Growth retardation under lower N supply (30-80 mgL-1) results from restricted availability of photosynthetic pigments, carbon fixation and impaired water relations. Excess uptake of N under supply higher than 160 mgL-1 N, promoted as well physiological and developmental restrictions, by ion-specific toxicity or an indirect induced restriction of carbon fixation and energy availability.

Wang Z., Hassan M.U., Nadeem F., Wu L., Zhang F., Li X.

Magnesium deficiency is a frequently occurring limiting factor for crop production due to low levels of exchangeable Mg (ex-Mg) in acidic soil, which negatively affects sustainability of agriculture development. How Mg fertilization affects crop yield and subsequent physiological outcomes in different crop species, as well as agronomic efficiencies of Mg fertilizers, under varying soil conditions remain particular interesting questions to be addressed. A meta-analysis was performed with 570 paired observations retrieved from 99 field research articles to compare effects of Mg fertilization on crop production and corresponding agronomic efficiencies in different production systems under varying soil conditions. The mean value of yield increase and agronomic efficiency derived from Mg application was 8.5% and 34.4 kg kg-1 respectively, when combining all yield measurements together, regardless of the crop type, soil condition, and other factors. Under severe Mg deficiency (ex-Mg < 60 mg kg-1), yield increased up to 9.4%, nearly two folds of yield gain (4.9%) in the soil containing more than 120 mg kg-1 ex-Mg. The effects of Mg fertilization on yield was 11.3% when soil pH was lower than 6.5. The agronomic efficiency of Mg fertilizers was negatively correlated with application levels of Mg, with 38.3 kg kg-1 at lower MgO levels (0 - 50 kg ha-1) and 32.6 kg kg-1 at higher MgO levels (50 - 100 kg ha-1). Clear interactions existed between soil ex-Mg, pH, and types and amount of Mg fertilizers in terms of crop yield increase. With Mg supplementation, Mg accumulation in the leaf tissues increased by 34.3% on average; and concentrations of sugar in edible organs were 5.5% higher compared to non-Mg supplemented treatments. Our analysis corroborated that Mg fertilization enhances crop performance by improving yield or resulting in favorable physiological outcomes, providing great potentials for integrated Mg management for higher crop yield and quality.

Maluleke M.K., Thobejane K.R.

Abstract The eradication of poverty and malnutrition are some of the main goals set by the United Nations through the Sustainable Development Goals (SDGs) 1 and 2. Humans have traditionally used Cannabis sativa L. for a variety of purposes, including medicine and as a raw ingredient for goods with added value such as drinks, cakes, and oil. The crop has gained considerable popularity in various industries due to its usage either as a fresh or processed material. The growing demand for Cannabis sativa’s raw materials for a range of applications has led to a steady increase in its cultivation. Because of this constant growing demand, it is essential that growers have a thorough awareness of all environmental conditions, particularly light intensity and the right fertiliser, for improvement of plant growth, yield and quality. Therefore, the study objective was to investigate the combined effect of different fertiliser types (chemical and organic) on the yield and biochemical constituents of Cannabis sativa under varying growing environments (shade net and open space), to enable comparative analysis to be done to assist growers in producing high-quality Cannabis sativa crops for commercial purposes. Fresh and freeze-dried samples were used to measure the yield and biochemical constituents. The treatment combination of shade net and chemical fertiliser resulted in superior inflorescence water content (40.2 g) and total phenols (14.7 GAE/100 g DW) compared to other treatments. Potassium content (989 mg/100 g DW) was superior under the treatment combination of chemical fertiliser and the open space environment compared to other treatments. Therefore, growers must consider the combination of light intensity and chemical fertiliser for yield and quality maximisation, whether under shade net or open space growing environments.

Lyu D., Ruan E.D., Backer R., Gagné-Bourque F., Smith D.L.

Hussain A., Abidi S.H., Syed Q.

Cannabis is a very novel plant genus which is important for both animals and human nutrition. This study reviewed the reported data on the physicochemical, nutritional and elemental/metal profiles of Cannabis species. On the basis of collected data here, the minimum range of moisture content reported was 1.1% in seeds and maximum 11.90% in C. indica. Maximum oil content of 51.06% in seeds with minimum 3.7% and maximum 25.7% ash content in the seeds and extracted flower of C. sativa (hemp) were reported. Varied nutrients with varying levels in Cannabis were documented such as proteins (minimum 4.21% in stem of C. indica and maximum 43.04% in seeds of C. sativa-hemp), carbohydrates (minimum 4% and maximum 43% in seeds of C. sativa-hemp), fiber (minimum 2.9% and maximum 40.4% in seeds of C. sativa-hemp) and fat (minimum 2.67% in stem of C. indica and maximum 55% in seeds of C. sativa-hemp). More than 30 fatty acids were reported in the seeds with maximum content of linoleic acid (62.89%), a-linolenic acid (23.43%) and oleic acid (18.8%). The maximum SFAs, UFAs, PUFAs, MUFAs, ω-3 and ω-6 fatty acids with 18 amino acids in Cannabis seeds were reported. Around 36 macro and micro elements with heavy metals like Hg, Pb, Cd and As with varied concentrations were reported in Cannabis. Cannabis is therefore one of the potential nutrient sources and its seeds specifically are important for product development and drug formulations.

Malík M., Praus L., Kuklina A., Velechovský J., Janatová A.K., Klouček P., Mládek V., Tlustoš P.

Bibi A., Rasul F., Shahzad S., Sakrabani R., Din W.U., Mckenna P., Sajid M.

The purpose of this review was to look into the different ways that heavy metal stress affects spinach, and how hazardous they are to soil, people's health, and plant ecosystems. Heavy metals in soil are caused by anthropogenic and industrial activity, and when they accumulate in food chains, they pose a major risk to human health. This paper presents an overview of heavy metals' negative impacts on soil fertility, plant physiology, and human health. Using spinach as a model plant, it is simple to cultivate and maintain, making it a diverse choice for studying how plants respond to stresses such as heavy metals. They describe how heavy metal stress affects spinach morphology and physiology, including absorption, detoxification, and translocation throughout the plant system. Understanding these procedures is critical when assessing the potential risks associated with the accumulation of hazardous components in spinach's edible parts. This review investigates the impact of heavy metal stress on the nutritional quality and yield of spinach after metal exposure. It is critical to investigate numerous strategies for reducing heavy metal stress in spinach, including soil remediation approaches, phytoremediation capabilities, and genetic procedures aimed to increase plant resistance to metals. The goal of this overview is to shed light on the mechanisms underlying the effects of heavy metals on spinach and to propose strategies to alleviate them, thereby protecting agricultural sustainability and public health (Fig. 1).

Saloner A., Sade Y., Bernstein N.

Ahmadi F., Kallinger D., Starzinger A., Lackner M.

Hemp (Cannabis sativa L.), renowned for its applications in environmental, industrial, and medicinal fields, is critically evaluated in this comprehensive review focusing on the impacts of chemical and organic fertilizers on its cultivation. As hemp re-emerges as a crop of economic significance, the choice between chemical and organic fertilization methods plays a crucial role in determining not only yield but also the quality and sustainability of production. This article examines the botanical characteristics of hemp, optimal growth conditions, and the essential biochemical processes for its cultivation. A detailed comparative analysis is provided, revealing that chemical fertilizers, while increasing yield by up to 20% compared to organic options, may compromise the concentration of key phytochemicals such as cannabidiol by approximately 10%, highlighting a trade-off between yield and product quality. The review presents quantitative assessments of nitrogen (N), phosphorus (P), and potassium (K) from both fertilizer types, noting that K significantly influences the synthesis of terpenes and cannabinoids, making it the most impactful element in the context of medicinal and aromatic hemp varieties. Optimal rates and timing of application for these nutrients are discussed, with a focus on maximizing efficiency during the flowering stage, where nutrient uptake directly correlates with cannabinoid production. Furthermore, the challenges associated with the U.S. industrial hemp market are addressed, noting that reducing production costs and improving processing infrastructure is essential for sustaining industry growth, especially given the slow expansion in fiber and cannabidiol markets due to processing bottlenecks. The review concludes that while chemical fertilizers may offer immediate agronomic benefits, transitioning towards organic practices is essential for long-term environmental sustainability and market viability. The future of the hemp industry, while promising, will depend heavily on advancements in genetic engineering, crop management strategies, and regulatory frameworks that better support sustainable cultivation practices. This nuanced approach is vital for the industry to navigate the complex trade-offs between productivity, environmental health, and economic viability in the global market.

Morgan W., Singh J., Kesheimer K., Davis J., Sanz-Saez A.

Floral Hemp (Cannabis sativa L.) is a new crop of interest due to its capacity of producing medicinally active substances such as cannabidiol (CBD) and other cannabinoids and low tetrahydrocannabinol (THC). Preliminary experiments performed in high-THC cannabis have found that light drought stress close to inflorescence maturity can increase THC levels raising concerns about the negative effects that drought can have on floral hemp production. Therefore, the objective of this study was to examine the effects of various timings and levels of drought on floral hemp yield, CBD and THC content. The hemp cultivars 'BaOx' and 'Cherry Mom' were planted in a commercial greenhouse setting in 2021 and 2022 and grown under well-watered conditions until flowering, at which drought treatments started. Moderate drought intensities (30–50 % field capacity) did not modify yield or THC and cannabidiol (CBD) levels. However, intense drought treatments led to significantly decreased yield and THC and CBD concentrations. Overall, drought stress reduced the THC percentage less than CBD, therefore decreasing the CBD:THC ratio. This research also demonstrates that intense drought decreases THC and CBD content instead of increasing it.

Berni R., Thiry M., Hausman J., Lutts S., Guerriero G.

Cannabis sativa L. is a species of great economic value. It is a medicinal plant that produces several bioactive phytochemicals, and the stems of the industrial cultivars, commonly referred to as “hemp”, are sources of both cellulosic fibers and hurds used in textiles and bio-composites. Environmental stresses of biotic and abiotic nature affect plant development and metabolism and can, consequently, impact biomass yield and phytochemical content. Stress factors can be divided into eustressors and distressors; while the former stimulate a positive response in terms of growth, productivity, and resistance, the latter impair plant development. Eustressors are factors that, applied at low–moderate doses, can improve plant performance. Several studies have investigated different types of distress in C. sativa and evaluated the impact on biomass and phytochemicals, while less attention has been paid to the study of eustress. This review discusses the concept of plant eustress by referring to the recent literature and extrapolates it to applications in C. sativa cultivation. The data available on the response of C. sativa to exogenous factors are reviewed, and then, salinity eustress applied to hemp cultivation is taken as a proof-of-concept example. The knowledge developed on plant eustress and the results collected so far are discussed in light of future applications to improve the production of biomass and phytochemicals in plants of economic interest. Emphasis is placed on the potential use of eustress in conjunction with other factors shown to impact both the physiological response and metabolism of Cannabis, among which there are macronutrients and biofertilizers. Perspectives are also drawn with respect to applying the knowledge developed on the elicitation of whole plants to Cannabis cell suspension cultures, which provide a controlled, scalable, and season-independent platform to produce secondary metabolites.

Saloner A., Bernstein N.

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.