Micronutrient Accumulation Research Articles

Biofortifying multiple micronutrients and decreasing arsenic accumulation in rice grain simultaneously by expressing a mutant allele of OAS-TL gene.

Rice grains typically contain relatively high levels of toxic arsenic (As) but low levels of essential micronutrients. Biofortification of essential micronutrients while decreasing As accumulation in rice would benefit human nutrition and health. We generated transgenic rice expressing a gain-of-function mutant allele astol1 driven by the OsGPX1 promoter. astol1 encodes a plastid-localized O-acetylserine (thiol) lyase (OAS-TL) with Ser189Asn substitution (OsASTOL1S189N), which enhances cysteine biosynthesis by forming an indissociable cysteine synthase complex with its partner serine acetyltransferase (SAT). The effects on growth, As tolerance, and nutrient and As accumulation in rice grain were evaluated in hydroponic, pot and field experiments. The expression of OsASTOL1S189N in pOsGPX1::astol1 transgenic lines enhanced SAT activity, sulphate uptake, biosynthesis of cysteine, glutathione, phytochelatins and nicotianamine, and enhanced tolerance to As. The expression of OsASTOL1S189N decreased As accumulation while increased the accumulation of multiple macronutrients (especially sulphur, nitrogen and potassium) and micronutrients (especially zinc and selenium) in rice grain in a pot experiment and two field experiments, and had little effect on plant growth and grain yield. Our study provides a new strategy to genetically engineer rice to biofortify multiple essential nutrients, reducing As accumulation in rice grain and enhancing As tolerance simultaneously.

Soil Solution Properties of Tropical Soils and Brachiaria Growth as Affected by Humic Acid Concentration

The soil solution is the compartment where plants uptake nutrients and this phase is in equilibrium with the soil solid phase. Changes in nutrient content and availability in the soil solution can vary among soil types in response to humic acid concentrations, thereby affecting Brachiaria growth. However, there are no studies demonstrating these effects of humic acid application on different soil types and how they affect Brachiaria growth. Thus, the aim of this study was to evaluate the effects of humic acid concentrations (0, 5, 10, 25, and 60 mg kg−1 carbon-humic acid) on Brachiaria brizantha growth and soil solution properties of contrasting tropical soils. Plants were grown for 35 days in greenhouse conditions in pots containing Sandy Entisol, Clayey (Red Oxisol), and Medium Texture (Red-Yellow Oxisol). Soil solution was assessed for pH, electrical conductivity (EC), carbon, and nutrient content. Shoot and root dry matter, as well as macro and micronutrients accumulation in the shoot, were determined. In a soil type-dependent effect, pH, EC, and concentrations of nutrients in solutions changed in response to carbon-humic acid concentration. In the less-buffered soils, Sandy Entisol and Red-Yellow Oxisol, the addition of 30–40 mg kg−1 carbon-humic acid increased root proliferation by 76–89%, while Brachiaria biomass produced in all soils increased by approximately 30%. Levels of carbon in solution were high (>580 mg L−1) and varied depending on the investigated soil type. Though solution carbon contents did not appear to be a driving factor controlling the positive effects of humic acid concentrations on Brachiaria dry matter, there was a direct relationship between other properties and nutrient content in the soil solution, and Brachiaria dry matter production.

The role of ruminant urine and faeces in the recycling of nutrients by forages

This study addresses the effect of using animal excreta on the nutritional content of forages, focusing on macro- and micro-element concentrations (nitrogen; N, phosphorus; P, sulphur; S, copper; Cu, zinc; Zn, manganese; Mn, selenium; Se) from animal feed to excreta, soil, and plants. Data were collected from pot and field trials using separate applications of sheep or cattle urine and faeces. Key findings indicate that soil organic carbon (SOC) and the type of excreta significantly influences nutrient uptake by forages, with varied responses among the seven elements defined above. Although urine contributes fewer micronutrients compared to faeces (as applied at a natural volume/mass basis, respectively), it notably improves forage yield and micronutrient accumulation, thus potentially delivering positive consequences at the farm level regarding economic performance and soil fertility when swards upon clayey soil types receive said urine in temperate agro-climatic regions (i.e., South West England in the current context). In contrast, faeces application in isolation hinders Se and Mn uptake, once again potentially delivering unintended consequences such as micronutrient deficiencies in areas of high faeces deposition. As it is unlikely that (b)ovine grazing fields will receive either urine or faeces in isolation, we also explored combined applications of both excreta types which demonstrates synergistic effects on N, Cu, and Zn uptake, with either synergistic or dilution effects being observed for P and S, depending largely on SOC levels. Additionally, interactions between excreta types can result in dilution or antagonistic effects on Mn and Se uptake. Notably, high SOC combined with faeces reduces Mn and Se in forages, raising concerns for grazed ruminant systems under certain biotic situations, e.g., due to insufficient soil Se levels typically observed in UK pastures for livestock growth. These findings underscore the importance of considering SOC and excreta nutritional composition when designing forage management to optimize nutrient uptake. It should be noted that these findings have potential ramifications for broader studies of sustainable agriculture through system-scale analyses, as the granularity of results reported herein elucidate gaps in knowledge which could affect, both positively and negatively, the interpretation of model-based environmental impact assessments of cattle and sheep production (e.g., in the case of increased yields [beneficial] or the requirement of additional synthetic supplementation [detrimental]).

Biofortification of Major Crops through Conventional and Modern Biotechnological Approaches to Fight Hidden Hunger: An Overview

Biofortification, the process of enhancing the nutritional content of crops, offers a promising strategy to combat hidden hunger—micronutrient deficiencies affecting over two billion people globally. This review article explores the biofortification of major crops, focusing on both conventional breeding techniques and modern biotechnological approaches. Conventional methods, such as selective breeding and crossbreeding, have been instrumental in increasing the levels of essential micronutrients like iron (Fe) and zinc (Zn) in staple crops such as wheat, rice, and maize. For instance, wild relatives of cultivated wheat, including Triticum dicoccoides and Aegilops tauschii, have been utilized to significantly enhance Fe and Zn content in modern cultivars. Advancements in biotechnological tools, including genetic engineering, marker-assisted selection (MAS), and genome editing (CRISPR/Cas9), have further accelerated the development of biofortified crops. These technologies enable precise modifications to increase the accumulation of micronutrients and improve nutrient bioavailability. For example, transgenic rice varieties enriched with β-carotene (Golden Rice) and enhanced Fe and Zn content through gene editing showcase the potential of biotechnology in addressing micronutrient deficiencies. The review also highlights ongoing efforts and challenges in the field, such as regulatory hurdles, public acceptance, and the need for comprehensive strategies integrating conventional and modern approaches. Furthermore, it discusses the role of international research organizations and collaborations in facilitating the development and dissemination of biofortified crops. In conclusion, combining conventional breeding with cutting-edge biotechnological innovations presents a robust approach to biofortify major crops, offering a sustainable solution to mitigate hidden hunger and improve global food security. Continued research and multi-disciplinary collaborations are essential to fully realize the potential of biofortification in enhancing human nutrition.

Physiological and molecular bases of the nickel toxicity responses in tomato

Nickel (Ni), a component of urease, is a micronutrient essential for plant growth and development, but excess Ni is toxic to plants. Tomato (Solanum lycopersicum L.) is one of the important vegetables worldwide. Excessive use of fertilizers and pesticides led to Ni contamination in agricultural soils, thus reducing yield and quality of tomatoes. However, the molecular regulatory mechanisms of Ni toxicity responses in tomato plants have largely not been elucidated. Here, we investigated the molecular mechanisms underlying the Ni toxicity response in tomato plants by physio-biochemical, transcriptomic and molecular regulatory network analyses. Ni toxicity repressed photosynthesis, induced the formation of brush-like lateral roots and interfered with micronutrient accumulation in tomato seedlings. Ni toxicity also induced reactive oxygen species accumulation and oxidative stress responses in plants. Furthermore, Ni toxicity reduced the phytohormone concentrations, including auxin, cytokinin and gibberellic acid, thereby retarding plant growth. Transcriptome analysis revealed that Ni toxicity altered the expression of genes involved in carbon/nitrogen metabolism pathways. Taken together, these results provide a theoretical basis for identifying key genes that could reduce excess Ni accumulation in tomato plants and are helpful for ensuring food safety and sustainable agricultural development.

Using multi-omics to explore the effect of Bacillus velezensis SAAS-63 on resisting nutrient stress in lettuce

To avoid the unreasonable use of chemical fertilizer, an environmentally friendly means of improving soil fertility is required. This study explored the role of the plant growth-promoting rhizosphere bacteria (PGPR) strain Bacillus velezensis SAAS-63 in improving nutrient stress in lettuce. Compared with no inoculation, B. velezensis SAAS-63 inoculants exhibited significantly increased fresh weight, root length, and shoot height under nutrient deficiency, as well as improved antioxidant activities and proline contents. The exogenous addition of B. velezensis SAAS-63 also significantly increased the accumulation of macroelements and micronutrients in lettuce. To elucidate the resistance mechanisms induced by B. velezensis SAAS-63 under nutrient stress, high-throughput sequencing and multi-omics analysis were performed. Inoculation with B. velezensis SAAS-63 altered the microbial community of the rhizosphere and increased the relative abundances of Streptomyces, Actinoallomurus, Verrucomicrobia, and Chloroflexi. It is worth noting that the inoculant SAAS-63 can affect plant rhizosphere metabolism. The inoculant changed the metabolic flow of phenylpropanoid metabolic pathway under nutrient deficiency and promoted phenylalanine to participate more in the synthesis of lignin precursors and coumarin substances by inhibiting the synthesis of flavone and isoflavone, thus improving plant resistance. This study showed that the addition of inoculant SAAS-63 could help plants recruit microorganisms to decompose and utilize trehalose and re-established the carbon metabolism of the plant rhizosphere. Additionally, microbes were found to be closely related to the accumulation of metabolites based on correlation analysis. The results indicated that the addition of PGPRs has an important role in regulating soil rhizosphere microbes and metabolism, providing valuable information for understanding how PGPRs affect complex biological processes and enhance plant adaptation to nutrient deficiency.Key points• Inoculation with SAAS-63 significantly promoted plant growth under nutrient-deficient conditions• Inoculation with SAAS-63 affected rhizosphere microbial diversity and community structure• Inoculation with SAAS-63 affected plant rhizosphere metabolism and induced plants to synthesize substances that resist stressGraphical abstract

Integrative chemical, physiological, and metabolomics analyses reveal nanospecific phytotoxicity of metal nanoparticles

The increasing application of metal nanoparticles (NPs) via agrochemicals and sewage sludge results in non-negligible phytotoxicological risks. Herein, the potential phytotoxicity of ZnO and CuO NPs on wheat was determined using integrative chemical, physiological, and metabolomics analyses, in comparison to Zn2+ and Cu2+. It was found that ZnO or CuO NPs had a stronger inhibitory effect on wheat growth than Zn2+ or Cu2+. After exposure to ZnO or CuO NPs, wheat seedlings accumulated significantly higher levels of Zn or Cu than the corresponding Zn2+ or Cu2+ treatments, indicating the active uptake of NPs via wheat root. TEM analysis further confirmed the intake of NPs. Moreover, ZnO or CuO NPs exposure altered micronutrients (Fe, Mn, Cu, and Zn) accumulation in the tissues and decreased the activities of antioxidant enzymes. The metabolomics analysis identified 312, 357, 145, and 188 significantly changed metabolites (SCMs) in wheat root exposed to ZnO NPs, CuO NPs, Zn2+, and Cu2+, respectively. Most SCMs were nano-specific to ZnO (80%) and CuO NPs (58%), suggesting greater metabolic reprogramming by NPs than metal ions. Overall, nanospecific toxicity dominated the phytotoxicity of ZnO and CuO NPs, and our results provide a molecular perspective on the phytotoxicity of metal oxide NPs.

Enhancing Nutrition, Crop Resilience, and Food Security through Biofortification

Biofortification is a process of enhancing the nutritional quality of food crops through conventional plant breeding, genetic engineering, or agronomic practices. It has emerged as an important agricultural strategy to improve public health by increasing the micronutrient density in staple crops and vegetables. Biofortification provides a cost-effective and sustainable approach to combat micronutrient deficiencies, also known as hidden hunger, which affects over 2 billion people worldwide. This review provides an overview of biofortification efforts targeting major micronutrients such as iron, zinc, vitamin A, and folate. The genetic and molecular mechanisms underlying elevated micronutrient accumulation are discussed. The review also summarizes the impacts of biofortification in enhancing micronutrient intake, nutritional status, and health outcomes based on results from efficacy and effectiveness studies. The role of biofortification in building climate resilience and food security is also examined. Overall, biofortification has shown considerable promise in tackling malnutrition sustainably in developing countries. However, continued research and policy support are needed to maximize its impact on nutrition security worldwide.

Impact of some heavy metal accumulation in different organs on fish quality from Bardawil Lake and human health risks assessment

Bardawil Lake is a unique aquatic ecosystem that provides a habitat for various fish and other marine organisms. This study aimed to analyze the quality of fish species to prove that this lake is free of pollution, not other Egyptian lakes, due to the accumulation of some heavy metals (Cd, Pb, Cu, and Zn) in various tissues of fish species that were caught from this lake. Thirty-five fish samples were caught during the Spring of 2018 from seven different species: Mugil cephalus, Liza auratus, Sparus aurata, Dicentrarchus labrax, Siganus rivulatus, Anguilla angilla, and Solae solea. The Association of Official Analytical Chemists methods using a spectrophotometer determined the biochemical composition. In contrast, atomic absorption spectrometry (AAS) was employed to determine the heavy metals expressed by µg/g wet weight. Results exposed that the accumulation of essential micronutrient (Cu, Zn) content was higher than toxic elements (Cd & Pb) in muscles in order to Zn > Cu > Pb > Cd. Muscles < gills < liver in order of all metals except Pb with order muscles < liver < gills. The metals studied in the muscles were lower than those set by the WHO and the EU standards. The carcinogenic risk with lower allowable limits of 1 × 10–6 to 1 × 10–4 in both normal and high consumption groups; target and total target hazard quotients (THQ & HI) in muscles were < 1. The biochemical composition level was highest in the liver, except for protein, which was highest in muscle for all fish species. There is no evidence of harmful contaminants in the muscular tissue of the fish sampled from Bardawil Lake, although fishing activity. However, customers should know that health concerns may be associated with overeating fish.

COMPARATIVE BIOCHEMICAL CHARACTERISTICS OF FOREST AND GARDEN BILBERRIES AS A RATIONALE FOR USE AS A SOURCE OF FUNCTIONAL INGREDIENTS

The attention of researchers - developers and manufacturers of food products is deservedly attracted by bilberries due to the rich and various complex of natural components that are beneficial to health. Both wild-growing and cultivated bilberries are involved in the sphere of industrial processing. It is traditionally believed that a berry grown in natural habitats is more environmentally friendly and is not inferior to cultivated varieties in terms of nutritional value. The purpose of the work is to conduct a study of the biochemical composition of berries of forest and garden bilberries to analyze its ability to accumulate food and biologically active compounds. The studies were carried out using modern physicochemical analysis methods (spectrophotometric method, HPLC, atomic absorption method). It has been experimentally shown that garden bilberries accumulate significantly more sugars than forest bilberries The trend for indigestible carbohydrates is the opposite: wild-growing bilberries are characterized by a high content of fiber and pectin with a predominance of the protopectin fraction. According to the content of organic acids, no priorities were identified: forest and garden bilberries were characterized by almost the same content. However, malic acid prevails in wild bilberries, and citric acid prevails in garden bilberries. It has been experimentally proven that wild bilberries are significantly superior to garden bilberries in terms of the content of bioactive polyphenolic compounds, anthocyanins, vitamin C, and carotenoids. In the complex of polyphenolic compounds of forest and garden bilberries, the same representatives of flavonoids (quercetin, rutin, catechin, resveratrol) and their metabolic products, phenolic acids (gallic, cinnamic, chlorogenic, ferulic, lilac), were identified. With the same qualitative composition of anthocyanin compounds, differences in quantitative ratios were revealed: cyanidin-3-galactoside prevails in wild bilberries, and delphinidin-3-galactoside prevails in garden bilberries. As for macronutrients, potassium prevails in both types of bilberries, and more calcium accumulates in garden bilberries. Forest bilberries surpass garden bilberries in terms of micronutrient accumulation. Considering the results of the analysis of the chemical composition it is obvious that the berries of forest and garden bilberries are of exceptional interest to food technologists, since they are a source of biologically active and minor components useful for health, as well as natural dyes and antioxidants. Therefore, the use of bilberries and its processing products in the production of food products will make it possible to endow products with healthy properties and realize functional properties in food technologies.

Phytosiderophore pathway response in barley exposed to iron, zinc or copper starvation

Efficient micronutrient acquisition is a critical factor in selecting micronutrient dense crops for human consumption. Enhanced exudation and re-uptake of metal chelators, so-called phytosiderophores, by roots of graminaceous plants has been implicated in efficient micronutrient acquisition. We compared PS biosynthesis and exudation as a response mechanism to either Fe, Zn or Cu starvation. Two barley (Hordeum vulgare L.) lines with contrasting micronutrient grain yields were grown hydroponically and PS exudation (LC-MS) and root gene expression (RNAseq) were determined after either Fe, Zn, or Cu starvation. The response strength of the PS pathway was micronutrient dependent and decreased in the order Fe > Zn > Cu deficiency. We observed a stronger expression of PS pathway genes and greater PS exudation in the barley line with large micronutrient grain yield suggesting that a highly expressed PS pathway might be an important trait involved in high micronutrient accumulation. In addition to several metal specific transporters, we also found that the expression of IRO2 and bHLH156 transcription factors was not only induced under Fe but also under Zn and Cu deficiency. Our study delivers important insights into the role of the PS pathway in the acquisition of different micronutrients.

Application timing and duration of LED and HPS supplements differentially influence yield, nutrient bioaccumulation, and light use efficiency of greenhouse basil across seasons.

Three primary factors that impact plant growth and development are light quantity, quality, and duration. Commercial growers can manipulate these parameters using light-emitting diodes (LEDs) to optimize biomass yield and plant quality. There is significant potential to synergize supplemental lighting (SL) parameters with seasonal variation of ambient sunlight to optimize crop light use efficiency (LUE), which could increase biomass while reducing SL electricity costs. To determine the best lighting characteristics and durations for different crops, particularly for enhancing the yield and nutritional quality of high-value specialty crops produced in greenhouses during the winter, a thorough efficacy comparison of progressive incremental daily light integrals (DLIs) using LED and high-pressure sodium (HPS) sources is required. The purpose of this study was to compare the effects of differential application timing and DLIs of supplemental blue (B)/red (R) narrowband wavelengths from LED lighting systems and HPS lamps on greenhouse hydroponic basil (Ocimum basilicum var. 'Genovese') production. We assessed edible biomass, nutrient bioaccumulation, and LUE. Nine light treatments included: one non-supplemented natural light (NL) control, two end-of-day (EOD) HPS treatments applied for 6h and 12h, five EOD 20B/80R LED treatments applied for 3h, 6h, 9h, 12h, 18h, and one continuous LED treatment (24h). Each SL treatment provided 100 µmol·m-2·s-1. The DLI of the NL control averaged 9.9mol·m-2·d-1 during the growth period (ranging from 4 to 20mol·m-2·d-1). SL treatments and growing seasons significantly impacted biomass and nutrient bioaccumulation; some SL treatments had lower yields than the non-supplemented NL control. January growing season produced the lowest fresh mass (FM) and dry mass (DM) values compared to November, which had the highest. Mineral analyses revealed that both growing seasons and lighting types impacted macro and micronutrient accumulation. Additionally, the efficiency of each treatment in converting electrical energy into biomass varied greatly. EOD supplements using LED and HPS lighting systems both have merits for efficiently optimizing yield and nutrient accumulation in basil; however, biomass and nutrient tissue concentrations highly depend on seasonal variation in ambient sunlight in conjunction with a supplement's spectral quality, DLI, and application schedule.

Relative role of soil nutrients vs. carbon availability on soil carbon mineralization in grassland receiving long-term N addition

High nitrogen (N) input often induces soil carbon (C) limitation, eutrophication of macronutrients, deficiency of base cations, and accumulation of toxic micronutrients. These changes are perceived to be critical factors in regulating soil C mineralization. Previous studies primarily focused on the individual effects of C, macronutrients, exchangeable base cations, and micronutrients on soil C mineralization. However, the relative importance of those factors in regulating soil C mineralization, especially in N-enriched ecosystems, remains unclear. To disentangle the relative contributions of aforementioned factors, lime and/or glucose were added to soils that were collected from a field experiment with historical N addition (6 years) at seven rates (0–50 g N m−2 year−1) in a grassland ecosystem. Lime and glucose were added to improve the soil C and key nutrient conditions. The responses of soil C mineralization rate to changes in soil C and macronutrients (N and P), exchangeable base cations (K+, Na+ and Mg2+), and micronutrients (Fe2+, Mn2+, Cu2+ and Zn2+) were examined. We found that lime addition decreased soil micronutrients, while glucose addition improved the soil available P and exchangeable base cations, especially at high historical N addition rates. The soil C mineralization was weakly associated with changes in soil nutrients, including the availability of N, P, exchangeable base cations, and micronutrients, which were conventionally and previously considered as the vital drivers of soil C mineralization. However, soil C mineralization strongly increased with glucose-induced enhancement of C availability and the subsequent enhancement of microbial biomass under increasing N addition rates. Based on the Structural Equation Model, the standardized total effects of C, macronutrients (N and P), base cations and micronutrients on soil C mineralization were 0.86, − 0.29, 0.15 and − 0.08, respectively. Findings from this study demonstrated that the N-induced significant changes in soil nutrients (e.g., eutrophication of N and P, base cations deficiency and accumulation of toxic macronutrients) mediated soil C mineralization, with C availability being the most critical driver for C mineralization in N-enriched soil. This study provides insight into the mechanistic understanding of the relationship between N input and terrestrial C cycling.

The Interplay of Sulfur and Selenium Enabling Variations in Micronutrient Accumulation in Red Spinach.

Aside from its importance in human and animal health, low levels of foliar-applied selenate (SeO4) can be advantageous in the presence of sulfur (S), contributing to improved growth, nutrient uptake, and crop quality. A hydroponic experiment in a growth chamber explored the interactive influence of Se and S on micronutrients and several quality indices, such as soluble sugars, organic acids, and total protein concentrations in spinach (Spinacia oleracea L.). Three levels of S (deprivation, adequate, and excessive) with varying quantities of Se (deficient, moderate, and higher) were examined in combination. Under S starvation and along with S nourishment in plant parts, Se treatments were found to cause noticeable variations in plant biomass and the concentrations of the examined elements and other quality parameters. Both Se levels promoted S accumulation in S-treated plants. Although the Se treatment had the opposite effect in shoots, it had a favorable impact on minerals (apart from Mn) in roots grown under S-limiting conditions. The S and Se relationship highlighted beneficial and/or synergistic effects for Mn and Fe in edible spinach portions. Reducing sugars were synergistically boosted by adequate S and moderate Se levels in roots, while in shoots, they were accumulated under moderate-or-higher Se and excessive S. Furthermore, the concentration of the quantified organic acids under S-deficient conditions was aided by various Se levels. In roots, moderate Se under high S application enhanced both malic acid and citric acid, while in the edible parts, higher Se under both adequate and elevated S levels were found to be advantageous in malic acid accumulation. Moreover, by elevating S levels in plant tissues, total protein concentration increased, whereas both moderate and high Se levels (Se1 and Se2) did not alter total protein accumulation in high S-applied roots and shoots. Our findings show that the high S and medium Se dose together benefit nutrient uptake; additionally, their combinations support soluble sugars and organic acids accumulation, contributing ultimately to the nutritional quality of spinach plants. Moreover, consuming 100 g of fresh red spinach shoot enriched with different Se and S levels can contribute to humans' daily micronutrients intake.

Fresh/High-Zinc Maize: A Promising Solution for Alleviating Zinc Deficiency through Significant Micronutrient Accumulation.

Zinc deficiency poses a significant health challenge worldwide, particularly in regions where access to and the affordability of dietary diversity are limited. This research article presents a time course analysis of kernel development on the zinc content in maize kernels with different genetic backgrounds, including normal maize, quality protein maize, and high-zinc maize, grown at two locations. Zn concentrations during stage I were high, decreasing between stages II and IV and increasing during stages V to VII. High-zinc kernel genotypes, including those ones with high-quality protein genetic backgrounds, have higher contents of zinc and iron during the milky stage (fresh/green maize). The zinc and iron content in fresh maize differed depending on the genotype. By consuming fresh maize biofortified with zinc, up to 89% and 100% of EAR needs can be fulfilled for pregnant women and children. The results demonstrate that fresh high-zinc maize accumulates a substantial amount of this micronutrient, highlighting its potential as a valuable source for addressing zinc deficiency.

The Use of Silicon Substrate Amendments to Decrease Micronutrient Concentrations at Varying Micronutrient Fertility Rates with Cannabis sativa ‘Auto CBG’

Many abiotic factors impact the yield and growth of Cannabis sativa (cannabis). Cannabis has been reported to be a bio-accumulator of heavy metals. For growers who are targeting floral production and other byproducts for human consumption, this is a concern. Silicon (Si) has been examined as a beneficial plant element to limit the uptake of heavy metals in a variety of crops. The objective of this study was to determine the impact of Si on heavy metal micronutrient uptake and plant growth for greenhouse-cultivated cannabis at varying Si substrate amendments. ‘Auto CBG’ plants were grown in a 70:30 peat:perlite substrate with one of three varying calcium silicate (CaSiO3) (Si) substrate amendment rates, Si0X, Si0.5X, or Si1X (of 0.0, 1.04, and 2.07 kg⋅m−3 CaSiO3), and one of three micronutrient fertility treatments, M1X [0.49 boron (B), 0.19 copper (Cu), 4.02 iron (Fe), 0.99 manganese (Mn), 0.01 molybdenum (Mo), and 0.20 zinc (Zn) mg⋅L−1], M2X, or M4X, using a modified Hoagland’s solution, creating a 3 × 3 factorial. Plants grown with a Si1X substrate amendment exhibited a significantly lower iron concentration in the foliage and root tissue when compared with those grown in a substrate without Si. After 6 weeks of growth, Si0X plants that received a M4X fertility rate exhibited greater foliar micronutrient concentrations of B, Mn, Zn, Fe, and Cu than plants that received a Si substrate amendment when provided a M4X fertility rate. Additionally, lower micronutrient concentrations in floral tissue were observed in plants that received a Si substrate amendment for M2X and M4X when compared with plants that did not. Silicon substrate amendments had no impact on the cannabinoid concentration or plant growth metrics after 12 weeks of growth. This research suggests that using a Si substrate amendment in a greenhouse production system can limit excessive uptake and accumulation of micronutrients in the foliage, roots, and floral material of cannabis without negative impacts on plant growth or cannabinoid concentrations.

Iron toxicity downregulates root-proton efflux and decreases zinc accumulation in cassava

Iron (Fe) plays a pivotal role in biogeochemical cycling in the soil-plant-human continuum; however, much research has focused on Fe deficiency with limited knowledge about Fe toxicity impacts on micronutrient (e.g., zinc: Zn) accumulation in cassava, an important staple tuber food in the Tropics. A sand-hydroponic-hybrid technique was undertaken for 60 days to investigate the effects of variable Fe concentrations (0.1–500 μmol Fe L−1) on the root-proton and root-organic acid release, rhizosphere Fe solubility, and levels of cassava nutrient accumulation. The results showed that high Fe concentrations (50–500 μmol Fe L−1) significantly decreased the root (0.34–0.51 g dry weight) biomass compared to the control (0.82–0.83 g dry weight). The Fe concentrations significantly regulated the net proton release from the roots by upregulating (25–45 μmol L−1 h−1 g−1 fresh weight root) and downregulating (1.8–7.1 μmol L−1 h−1 g−1 fresh weight root) the net proton efflux at low (1.0 μmol Fe L−1) and high Fe concentrations (500 μmol Fe L−1), respectively. Succinic acid was the sole organic acid observed and only in the Fe-sensitive cultivar. The water-extractable Fe in the rhizosphere sand (average 3.37 mg kg−1) was lower than in the bulk sand (average 5.31 mg kg−1), indicating that net proton efflux controlled rhizosphere Fe solubility. The high Fe concentrations significantly decreased Zn accumulation (20–29 mg Zn kg−1) but increased phosphorus (P) accumulation (2.7–3.4 g P kg−1) in the roots compared to the control (48–59 mg Zn kg−1 and 2.0–2.3 g P kg−1, respectively), implying that Fe toxicity could be responsible for the undernourished Zn content in the tuber. This study suggested the importance of alleviating Fe toxicity in soil-plant systems to mitigate cassava root Zn deficiency, which is relevant to human Zn malnutrition in countries consuming cassava as the main staple diet.

Macro and Micro-Nutrient Accumulation and Partitioning in Soybean Affected by Water and Nitrogen Supply.

This study aimed to investigate the influence of water availability and nitrogen fertilization on plant growth, nutrient dynamics, and variables related to soybean crop yield. Trials were performed in Teresina, Piauí, Brazil, using randomized blocks in a split-split plot arrangement. The plots corresponded to water regimes (full and deficient), the split plots to N fertilization (0 and 1000 kg ha-1 N-urea), and the split-split plots to harvest times of soybean plants (16, 23, 30, 37, 44, 58, 65, 79 and 86 days after emergence), with three replicates. In general, the accumulation and partitioning of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S), copper (Cu), iron (Fe), manganese (Mn), zinc (Zn) and boron (B) were decreased in plants subjected to water deficit and without N fertilization. Although nitrogen fertilization promoted elevated N accumulation in tissues, it did not result in any significant yield gain, and the highest seed yields were found in plants under full irrigation, regardless of N supplementation. However, deficient irrigation decreased the seed oil content of N-fertilized plants. In conclusion, N fertilization is critical for nutrient homeostasis, and water availability impairs biomass and nutrient accumulation, thereby limiting soybean yield performance.

Zinc biofortification through seed nutri-priming using alternative zinc sources and concentration levels in pea and sunflower microgreens.

Micronutrient deficiencies caused by malnutrition and hidden hunger are a growing concern worldwide, exacerbated by climate change, COVID-19, and conflicts. A potentially sustainable way to mitigate such challenges is the production of nutrient-dense crops through agronomic biofortification techniques. Among several potential target crops, microgreens are considered suitable for mineral biofortification because of their short growth cycle, high content of nutrients, and low level of anti-nutritional factors. A study was conducted to evaluate the potential of zinc (Zn) biofortification of pea and sunflower microgreens via seed nutri-priming, examining the effect of different Zn sources (Zn sulfate, Zn-EDTA, and Zn oxide nanoparticles) and concentrations (0, 25, 50, 100, and 200 ppm) on microgreen yield components; mineral content; phytochemical constituents such as total chlorophyll, carotenoids, flavonoids, anthocyanin, and total phenolic compounds; antioxidant activity; and antinutrient factors like phytic acid. Treatments were arranged in a completely randomized factorial block design with three replications. Seed soaked in a 200 ppm ZnSO4 solution resulted in higher Zn accumulation in both peas (126.1%) and sunflower microgreens (229.8%). However, an antagonistic effect on the accumulation of other micronutrients (Fe, Mn, and Cu) was seen only in pea microgreens. Even at high concentrations, seed soaking in Zn-EDTA did not effectively accumulate Zn in both microgreens' species. ZnO increased the chlorophyll, total phenols, and antioxidant activities compared to Zn-EDTA. Seed soaking in ZnSO4 and ZnO solutions at higher concentrations resulted in a lower phytic acid/Zn molar ratio, suggesting the higher bioaccessibility of the biofortified Zn in both pea and sunflower microgreens. These results suggest that seed nutrient priming is feasible for enriching pea and sunflower microgreens with Zn. The most effective Zn source was ZnSO4, followed by ZnO. The optimal concentration of Zn fertilizer solution should be selected based on fertilizer source, target species, and desired Zn-enrichment level.

N-Source Determines Barley Productivity, Nutrient Accumulation, and Grain Quality in Cyprus Rainfed Agricultural Systems.

The Eastern Mediterranean and Middle East (EMME) region is already experiencing the negative effects of increased temperatures and the increase in prolonged drought periods. The use of organic fertilization could be a valuable tool to meet the main challenges of climate change and maintain the productivity, quality, and sustainability of rainfed agricultural ecosystems. In the current study, we compare the effect of manure, compost, and chemical fertilization (NH4NO3) on barley grain and straw yield in a field study for three consecutive growing seasons. The hypothesis that the barley productivity, nutrient accumulation, and grain quality remain similar among the different nutrient management strategies was tested. The results showed that both growing season and type of nutrient source significantly affected barley grain and straw yield (F6,96 = 13.57, p < 0.01). The lowest productivity was noticed in the non-fertilized plots while chemical and organic fertilization exhibited similar grain yield, ranging from 2 to 3.4 t/ha throughout the growing seasons. For straw, the use of compost had no effect on the yield in any of the growing seasons examined. The use of manure and compost had a significant effect on grain macro- and micronutrient content but this was highly related to growing season. Principal component analysis (PCA) clearly demonstrated the discrimination of the different type of fertilization on barley performance during the course of the study, while the application of compost was highly associated with an increase in micronutrients in grain samples. Furthermore, structural equational modeling (SEM) showed that both chemical and organic fertilization had a direct positive effect on macro- (r = 0.44, p < 0.01) and micronutrient (r = 0.88, p < 0.01) content of barley grain and a positive indirect effect on barley productivity through N accumulation in grain (β = 0.15, p = 0.007). The current study showed that barley grain and straw yield was similar between manure and NH4NO3 treatments, while compost exhibited a residual positive effect causing an increase in grain yield during the growing season. The results highlight that N fertilization under rainfed conditions is beneficial to barley productivity through its indirect effects on N accumulation in grain and straw, while it improves grain quality through the increased accumulation of micronutrients.