Development of a method to screen soybeans (Glycine max (L.) Merrill) for sensitivity to zinc deficiency

The changes over time in soil pH, plant growth and zinc uptake by soybean (Glycine max (L.) Merr.) cv. Wills grown in a zinc-deficient black earth under two watering regimens, viz. watering to weight (WTW) and constant water table (CWT), were determined in a pot experiment. In the absence of applied zinc, CWT plants achieved twice the dry matter yield of WTW plants. Interveinal chlorosis was observed on CWT plants at 20 days after sowing, but not on WTW plants at any time during the experiment. Leaf lamina zinc concentrations at a number of nodes were less than 10 �g g-1 in plants grown for 25 days under both watering regimens. Fertilization with zinc at 30 kg zinc ha-1 significantly increased the dry matter yield of CWT plants and, particularly, the size of laminae at node 5 and above. Plants grown in the absence of applied zinc recovered from zinc deficiency over the period from 25 to 35 days after sowing. Rates of dry matter and zinc accumulation over this period increased, while zinc concentrations in the plant and particularly in the younger leaves increased markedly. This recovery coincided with a substantial decline in soil pH. The recovery from zinc stress is attributed to the greatly increased availability of zinc to the plant roots which may have resulted from the drop in soil pH.

Effects of zinc supply on the distribution of zinc and dry weight among plant parts were examined during the first 55 days of vegetative development of Seaton Park subterranean clover grown in a zinc-deficient soil in a glasshouse. Symptoms of zinc deficiency first appeared in young trifoliate leaves. Zinc deficiency decreased the expansion of blades and petioles, delayed the development of leaves and lateral branches, depressed dry weights of roots and shoots, and increased the proportion of plant dry weight in roots and leaf blades. In each treatment and at each harvest, zinc concentrations varied widely amongst plant parts and with their physiological age. Plant parts also differed widely in the response of their dry matter and zinc concentrations to both zinc treatment and harvest time. It is suggested that these complex relationships explain why plant samples consisting of composite plant parts are not suitable for diagnosis of zinc deficiency. In the present experiment, zinc concentration in whole shoots was unsatisfactory for diagnosing zinc deficiency since concentrations were higher in young, zinc-deficient plants than in older, zinc-adequate plants. In young leaf blades of the same physiological age, zinc concentrations showed reasonably constant relationships with plant growth throughout the entire experiment. However, they varied two- to three-fold in leaves of different ages from the same plants. The results show the importance for diagnosis of zinc deficiency of selecting as a sample a single organ of defined physiological age. The youngest open leaf blade is recommended for diagnosis of zinc deficiency in subterranean clover.

Zinc deficiency in soils and related malnutrition in humans pose serious threats both to cereal production and human health worldwide (Alloway, 2009; Cakmak et al., 2010; Zou et al., 2012; Velu et al., 2014). With two thirds of the world's agriculture land being marginal or severely zinc deficient and the current genetic erosion in wheat, maize and rice (FAO, 2013; Zou et al., 2012), there is a strong concern whether agronomic strategies for zinc biofortification would effectively enhance zinc concentrations for bioavailability to consumers post-processing. The major cereals are inherently low in zinc concentrations, thus fortified foods are inherently low in zinc concentrations. Therefore, a judicious use of zinc fertilisers (i.e., appropriate method, rate and timing) is likely to be the primary target not only for correcting soil deficiencies but also increasing zinc bioavailability globally (Alloway, 2009; FAO, 2013; Velu et al., 2014). A judicious use of zinc fertiliser has the potential for improving zinc status of crops up to fourfold from current baseline, and thus, producing crops with zinc concentrations that meet human requirement for dietary intakes. Improving zinc concentration in crops via agronomic strategies (i.e., soil and foliar fertilisation) lowers the risk of malnutrition and chronic diseases especially in children due to inadequate zinc intake and it limits the need for improving zinc nutrition via supplementation of commercial fortification (Alloway, 2009; Velu et al., 2014). However, there is a considerable contention among policy makers and analysts regarding the effectiveness of the soil and foliar application method for zinc biofortification and the crops for which it may or may not work (Cakmak, 2008). Soil and foliar application of fertilisers are two common agronomic strategies used to correct nutrient deficiencies in the soil and address plant demand for a specific nutrient. In the recent years, there has been an increasing interest and research about how these strategies could be used to increase zinc concentrations in the edible parts of crops, particularly wheat, maize and rice (Cakmak, 2008), in a way that best fits farmers’ interests and farm economics. This increasing interest results from the large investments that have been made for production of nutraceutical preparations and development of functional foods to address the occurrence of zinc deficiencies in the human diet. Generally, soil strategy involves application of granular Zn fertiliser, usually zinc sulphate (ZnSO4 . 7H2O), before sowing at rates based on soil test results of the soil properties prior to the intervention. Foliar strategy involves spraying a zinc (ZnSO4 . 7H2O) solution on the leaves one or multiple times during growth. For decades, the use of zinc fertilisers in agriculture has been justified economically for improving plant nutrition by increasing soil availability of nutrients for plant uptake and increasing productivity by increasing yields (Manzeke et al., 2012; 2014). Application of zinc fertilisers via soil or foliar approach is an agronomic short-term strategy that affects mainly mineral nutrition and yield of crops. However, the effects of soil and foliar fertilisation on zinc concentrations beyond basic plant nutrition and productivity remain not fully understood. While commercial zinc fortification has played a key role in addressing zinc malnutrition by producing zinc fortified foods, empirical evidence now show that agronomic zinc biofortification could be an attractive strategy to mitigate zinc deficiencies in the soil and related malnutrition in humans (Cakmak et al., 2008). Hence, there is a scope to identify not only zinc fertilisation methods that increase grain zinc concentrations and grain yield and minimise negative impacts on the environment and crop performance but also that could improve zinc bioavailability post-processing. This viewpoint prompted research about the effects of soil and foliar zinc fertilisation on zinc biofortification particularly in countries severely affected by zinc deficiency and malnutrition. Recently, several primary studies attempted to study the effects of soil and foliar zinc fertilisation on grain zinc concentrations and bioavailability of wheat, maize and rice (Cakmak et al., 2010; Phattarakul et al., 2012; Wang et al., 2015; Zou et al., 2012; Zhang et al., 2012; Li et al., 2015). The evidence suggests that foliar strategy is more effective than soil strategy in increasing grain zinc concentration with inverse relation to grain yield (Phattarakul et al., 2012; Ram et al., 2016). The evidence also shows that great proportion of grain Zn in wheat and rice comes from remobilisation from leaves before grain formation and from continuous uptake, respectively, suggesting that soil application would be more effective for zinc biofortification of rice and foliar application would be more effective for zinc biofortification of wheat (Waters and Sankara, 2011; Phattarakul et al., 2012). Ashong et al. (2012) reviewed the positives and negatives of rice biofortification with zinc and other minerals and vitamins on micronutrient status and health-related outcomes suggesting that industrial zinc fortification of rice could aid in the designing and implementation of appropriate food fortification. Brnic et al. (2016) studied zinc absorption from hydroponically and industrially zinc-fortified rice varieties by consumers fed with the same total zinc content meal, yet the study was inconclusive which strategy is more effective in increasing zinc bioavailability to consumers. Thus, evidence regarding the direct human health impacts of zinc biofortification is somewhat equivocal, largely because of low precision. Estimates based on the upper and lower confidence intervals of pooled effects from meta-analysis range from highly effective to no substantive effect (Ashong et al. 2012). Nevertheless, biofortification remains a mainstream development activity with annual spending millions of dollars. Identifying efficiencies in biofortification therefore remains an important development and food security objective. Although there has been extensive primary research on zinc biofortification through soil and foliar application of zinc fertilisers, to our knowledge, no systematic review has been published using systematic data collection, critical appraisal and statistical synthesis using network meta-analysis. The only existing evidence synthesis undertook a cost effectiveness analysis of the potential of zinc-enriched fertilisers to alleviate human dietary zinc deficiency in sub-Saharan countries (Joy et al. 2015). Whilst useful, this synthesis did not adopt the standard methodologies of systematic review to minimise bias. The synthesis was not guided by a protocol, searches and inclusion criteria were not specified, critical appraisal was not undertaken, effect modifiers and publication bias were not investigated and the reporting does not conform to the standards of the Methodological Expectations of Campbell Collaboration Intervention Reviews (MECCIR). Another existing systematic review focused on quantifying the effect of zinc deficiency on human health in relation to the incidence and related mortality risk of diseases such as diarrhoea, pneumonia and malaria, particularly among children in developing countries (Caulfield and Black, 2004). Nonetheless, this review did not assess the evidence regarding biofortification strategies to mitigate the prevalence of inadequate zinc intakes. In addition, none of the syntheses used network meta-analysis to compare multiple treatment effects and explore inconsistency. We are unaware of any network meta-analysis in agricultural research to date, despite its widespread use in other domains and clear application with multiple treatments regularly used in single study sites. Therefore, the present review is important because it could inform policy makers and food industries with respect to the use of inherent high zinc genotypes of the three major cereal crops for the development of functional foods worldwide. This review will evaluate the effects of zinc fertilisation in terms of increased grain zinc concentrations with potential for increased bioavailability to the consumer post-processing, and this review will also inform policy makers and farmers in relation to adoption of a zinc fertilisation method for zinc biofortification of the major cereals that could optimise utilisation efficiency, farm economics and environmental sustainability. The primary objective is to ascertain the effectiveness of zinc fertilisation methods on grain zinc concentrations and grain yield of wheat, maize and rice. Our secondary objective is to understand heterogeneity in the effectiveness of zinc biofortification with respect to postulated effect modifiers. Exploratory analyses will be undertaken to explore methodological variation (sensitivity analysis) and the impact of additional covariates notably location. Variation in study location will be considered in relation to the genetic diversity, agronomic management practices and ecological, climate and weather conditions. This review will be limited to studies examining the effect of application of zinc fertilisers on grain zinc concentration and yield of wheat, maize and rice will be included in the review. The study population will be wheat, maize and rice genotypes as determined by each individual primary study under zinc fertilisation. Studies focusing on wheat, maize and rice under a fertilisation regime other than zinc will not be included in the review, likewise studies examining the effect of soil and foliar application of zinc fertilisers on the yield and zinc concentration of crops other than wheat, maize and rice will not be included in the review. Although such studies might be useful to understanding zinc biofortification mechanisms and processes, they are not relevant to the target intervention and population of the present review. Intervention studies will be limited to those examining the effects of timing, rate and solute concentration of zinc fertiliser, through soil, foliar, and soil plus foliar application, on grain zinc concentration and grain yield of wheat, maize and rice will be included in the review. Soil, foliar and soil plus foliar applications are assumed to be comparable with high exchangeability and are assumed to be jointly randomizeable. This is a strong assumption which will be tested by comparison with results from pairwise meta-analysis and meta-regressions to explore inconsistency within pairwise treatments. In agricultural context, eligible comparisons include no application of zinc fertiliser. Data will be collected on comparison conditions and tested for systematic differences in effects accordingly in moderator analysis. Outcomes will be used to determine study eligibility. Grain zinc concentrations will be considered primary outcomes in this review. Secondary outcomes will be limited to grain yield. Grain zinc concentrations are usually measured in milligrams per kilogram (mg kg-1) and grain yield in tonnes per hectare (t ha-1). This review will not include outcomes relating to micronutrient status and human health. The meta-analyses will be used to parameterise a downstream systems model which will make explicit links between the systematic review outcomes and the quality of life and behaviour change factors of interest to policy makers. Heuristic discussion of these relationships will be included when considering the strength of evidence (indirectness) in the summary of findings. This review will include replicated field trials. Such studies will be included because of the practical implications of their findings on the decision-making for a generalised adoption or recommendation of a given fertilisation regime by farmers and policy makers. The review will include original primary research from all countries. Relevant studies written in a language other than English will be considered eligible for inclusion. Citation searches in Web of Science and Google Scholar for included studies will be conducted, and the names of key identified authors searched to ensure recent papers have not been missed. Key authors will also be contacted to request relevant papers not returned from the database search. Searches will not be refined by year of publication to ensure that all publications of an acceptable standard will be included in the review. The standard of papers will be dealt with through the quality assessment tool detailed below. Relevant search terms will be refined to ensure the most successful search strategies are used. All relevant search terms must be included in the topic, keywords, title and abstract sections of each individual paper returned by the database. The terms Biofortification*, Zinc bioavailability*, Zinc biofortification* OR Zinc fertilisation*, AND Zinc concentration*, OR Zinc distribution*, OR Grain zinc*, AND Zinc efficiency*, Zinc nutrition*, wheat*, maize*, rice* will be queried. We will also search the agricultural trials registry http://www.agtrials.org. The titles and abstracts of articles retrieved by each search will be screened independently by two review authors to assess eligibility as determined by the inclusion and exclusion outlined above. Full copies of all eligible papers will be retrieved. When a title or abstract cannot be rejected with certainty, the full text of the article will be obtained for further evaluation. If full articles cannot be obtained, we will attempt to contact the authors to obtain further details of the study. Failing this, studies will be classified as ‘awaiting assessment’ until further information is published or made available to us. Disagreements at any stage of the eligibility assessment process will be resolved through discussion and consultation with a third author, where necessary. Details of excluded studies at stage two will be listed in an appendix. Field research on agronomic zinc biofortification is well established with little or no variation in methodological quality. The little variability is in relation to fertiliser recommendations which follow guidelines established by individual countries based on soil test results. Glasshouse studies are also well established but with significant variation in methodological quality. These glasshouse studies are stronger in exploring and explaining mechanisms under controlled conditions but weaker in addressing fertiliser recommendations and extension programmes. Outcomes from glasshouse studies do not reflect conditions from the real world. Example of studies which are eligible for inclusion in the review are provided in Table (?). Example would be excluded are presented in Table (?). Two review authors will collect information from each study including study location (country, experimental site and year), study characteristics (crop species and genotype, initial soil pH and zinc status, form, application rate and timing of Zn fertiliser) and other critical management practices (NPK fertilisation, irrigation, pest/disease control). Means, sample size and standard deviation of the interventions will be extracted. Additionally, key insights and what the effect on grain zinc concentration and yield was will be recorded. Studies will be assessed in terms of clarity of aims, clarity and appropriateness of methodology, objectivity of outcome measurements, use of controls, and clarity of findings, which will be considered and reported in the descriptive analysis. Value judgements categorised as “good”, “bad” or “unclear” will be supported by a transparent rationale for the judgement. Potential sources of bias will be scored using a system indicating high risk, moderate risk and low risk of bias, as appropriate. The following categories of bias will be assessed (Waddington et al., 2012): confounding and sample selection bias; reporting biases; and other sources of bias. This involves consideration of within-study risk of bias (study limitations), directness of evidence, heterogeneity and precision of effect estimates. Sources of bias for statistical modelling studies will include factors relating to model specification (e.g. source of model coefficients) and methods of inference (e.g. use of systematic sensitivity analysis). No study will be excluded based on the critical assessment tool, but the findings will be considered during the evidence synthesis. The critical appraisal will inform the overall strength of the evidence and may inform sensitivity analysis. The statistical evidence in the papers will be extracted with the intention of comparing effects of soil, foliar and soil plus foliar application of zinc fertiliser on outcomes. A sample of data extraction will be done by two team members to ensure consistency. Changes will be examined in comparable criteria at harvest after zinc fertiliser has been applied, or has not been applied. Data will be collected from multiple locations and years and combined to ensure independence either using two stage analysis or hierarchical models depending on model complexity and convergence. Data will be extracted to compute mean difference effect sizes. All effect sizes will be calculated consistently, so that the direction of change reflects a uniform increase or decrease in the outcome variable across studies (e.g. where studies estimate effects of using soil or foliar or soil plus foliar strategy). The effect size will then be interpreted in relation to the minimum increase of 8 mg Zn.kg-1 in each crop from the baseline (in mg Zn/kg grain) of 16, 25 and 25 for rice, wheat and maize, respectively, as established by the HarvestPlus program for zinc biofortification interventions. Where measure of dispersion (i.e. standard error, standard deviation, confidence intervals) is not reported, primary study authors will be contacted to obtain this data, where possible. Failing this, standard deviation of the outcome variable will be imputed using a bootstrapping procedure based on runif in the R statistical software environment. No qualitative data is planned to be included in this review. Random effects network meta-analysis will be undertaken for each crop species separately. Effect sizes and 95 per cent confidence intervals will be presented using forest plots. Pairwise meta-analyses will be conducted to further explore the sources of heterogeneity where appropriate. Pairwise inconsistency will be assessed using the GRADE framework and heterogeneity quantified using I2. If excessive heterogeneity is detected in the data, then a narrative synthesis will instead be conducted guided by the data extraction form in terms of the ways in which studies may be grouped and summarised. The narrative analysis will follow guidance laid out in the ESRC Narrative Synthesis Guidance document (Popay et al, 2006). We will not explore inconsistency within the network itself because the models will not converge with the high number of covariates included in the exploration of heterogeneity. Instead we will perform pairwise meta-regressions using AIC/DIC to avoid overfitting. Moderator analysis will be conducted according to the moderator variables defined above, and if sufficient studies permit we will conduct analysis of publication bias using conventional methods such as funnel plots. The main findings of the review will be set out in summary of findings (SoF) tables incorporating primary outcomes only, to explain the significance of the findings. The outcome for each comparison will be listed with estimates of relative effects contributing data for those outcomes. No funding Gavin Stewart is an Associate Editor of Peer J, Research synthesis methods, and multiple Cochrane and Campbell entities. Paul Bilsborrow is a Senior Editor of the European Journal of Agricultural Science. Ismail Cakmak is a Review Editor of Frontiers in Plant Nutrition Published by Frontiers Journals. Zed Rengel is co Editor-in-Chief of Crop & Pasture Science (Australia) and Associate Editor of Crop Science (USA). The primary researcher will be responsible for updating the protocol if new evidence is available every five years. By completing this form, you accept responsibility for preparing, maintaining and updating the review in accordance with Campbell Collaboration policy. The Campbell Collaboration will provide as much support as possible to assist with the preparation of the review. A draft review must be submitted to the relevant Coordinating Group within two years of protocol publication. If drafts are not submitted before the agreed deadlines, or if we are unable to contact you for an extended period, the relevant Coordinating Group has the right to de-register the title or transfer the title to alternative authors. The Coordinating Group also has the right to de-register or transfer the title if it does not meet the standards of the Coordinating Group and/or the Campbell Collaboration. You accept responsibility for maintaining the review in light of new evidence, comments and criticisms, and other developments, and updating the review at least once every five years, or, if requested, transferring responsibility for maintaining the review to others as agreed with the Coordinating Group. The support of the Campbell Collaboration and the relevant Coordinating Group in preparing your review is conditional upon your agreement to publish the protocol, finished review and subsequent updates in the Campbell Library. Concurrent publication in other journals is encouraged. However, a Campbell systematic review should be published either before, or at the same time as, its publication in other journals. Authors should not publish Campbell reviews in journals before they are ready for publication in the Campbell Library. Authors should remember to include a statement mentioning the published Campbell review in any non-Campbell publications of the review. I understand the commitment required to undertake a Campbell review, and agree to publish in the Campbell Library. Signed on behalf of the authors: Form completed by: Gavin Stewart Date: 07/08/2017

Alleviation of zinc deficiency in plants and humans through an effective technique; biofortification: A detailed review

A greenhouse experiment was carried out to study severity of the zinc (Zn) deficiency symptoms on leaves, shoot dry weight and shoot content and concentration of Zn in 164 winter type bread wheat genotypes (Triticunt aestivum L.) grown in a Zn‐deficient calcareous soil with (+Zn=10 mg Zn kg−1 soil) and without (‐Zn) Zn supply for 45 days. Tolerance of the genotypes to Zn deficiency was ranked based on the relative shoot growth (Zn efficiency ratio), calculated as the ratio of the shoot dry weight produced under Zn deficiency to that produced under adequate Zn supply. There was a substantial difference in genotypic tolerance to Zn deficiency. Among the 164 genotypes, 108 genotypes had severe visible symptoms of Zn deficiency (whitish‐brown necrotic patches) on leaves, while in 25 genotypes Zn deficiency symptoms were slight or absent, and the remaining genotypes (e.g., 31 genotypes) showed mild deficiency symptoms. Generally, the genotypes with higher tolerance to Zn deficiency originated from Balkan countries and Turkey, while genotypes originating from the breeding programs in the Great Plains of the United States were mostly sensitive to Zn deficiency. Among the 164 wheat genotypes, Zn efficiency ratio varied from 0.33 to 0.77. The differences in tolerance to Zn deficiency were totally independent of shoot Zn concentrations, but showed a close relationship to the total amount (content) of Zn per shoot. The absolute shoot growth of the genotypes under Zn deficiency corresponded very well with the differences in tolerance to Zn deficiency. Under adequate Zn supply, the 10 most Zn‐ inefficient genotypes and the 10 most Zn‐efficient genotypes were very similar in their shoot dry weight. However, under Zn deficiency, shoot dry weight of the Zn‐efficient genotypes was, on average, 1.6‐fold higher compared to the Zn‐inefficient genotypes. The results of this study show large, exploitable genotypic variation for tolerance to Zn deficiency in bread wheat. Based on this data, total amount of Zn per shoot, absolute shoot growth under Zn deficiency, and relative shoot growth can be used as reliable plant parameters for assessing genotypic variation in tolerance to Zn deficiency in bread wheat.

Due to calcareous soil conditions, zinc deficiency is a yield limiting factor for wheat production in Iran. One solution for this problem is the cultivation of Zn-efficient wheat varieties. Ten wheat cultivars (nine bread wheat and one durum wheat) with different tolerance to Zn deficiency were studied in a greenhouse experiment. Plants were treated with Zn (10 mg Zn Kg-1 soil as ZnSO4.7H2O) and without it. Based on the results of pot experiment, two wheat cultivars with different Zn efficiency were selected to assess the ability of phytosiderophore release from their roots. Visual Zn deficiency symptoms, such as light colored necrotic patches and reduction in plant height appeared more severe in Alvand, Mahdavi (bread wheat) and Yavares (durum wheat) cultivars. Under Zn deficiency, shoot dry matter decreased in most cultivars. Zn efficiency of wheat cultivars ranged from 80.4% to 106.2%. Based on shoot dry weight, Pishtaz and Darab were the most Zn-efficient and Alvand and Mahdavi were the most Zn-inefficient wheat cultivars. Zn supply markedly increased the Zn concentration and content of shoots of all cultivars. Cultivars differed in Zn uptake under Zn-deficient and Zn-sufficient conditions. On average, Zn-efficient cultivars had more Zn uptake efficiency compared to Zn-inefficient cultivars. Our results strongly suggested that sensitivity to Zn deficiency varied widely among wheat cultivars. Different susceptibility of cultivars did not correspond well with the Zn concentration of the shoot. In contrast, the total amount of Zn of shoot was better related to the sensitivity of wheat cultivars to Zn deficiency. Under Zn deficiency, different ability of genotypes to release phytosiderophore from roots was observed. Pishtaz exuded more phytosiderophore than Alvand. Higher Zn uptake in Zn-efficient wheat genotypes may be attributed to higher release rates of Zn-mobilizing phytosiderophores from roots. Keywords: Wheat cultivars, Zinc efficiency, Zinc concentration, Zinc uptake

Zinc is an imperative micronutrient required for optimum plant growth. Zinc solubilizing bacteria are potential alternatives for zinc supplementation and convert applied inorganic zinc to available forms. This study was conducted to screen zinc solubilizing rhizobacteria isolated from wheat and sugarcane, and to analyze their effect on wheat growth and development. Fourteen exo-polysaccharides producing bacterial isolates of wheat were identified and characterized biochemically as well as on the basis of 16S rRNA gene sequences. Along these, 10 identified sugarcane isolates were also screened for zinc solubilizing ability on five different insoluble zinc sources. Out of 24, five strains, i.e., EPS 1 (Pseudomonas fragi), EPS 6 (Pantoea dispersa), EPS 13 (Pantoea agglomerans), PBS 2 (E. cloacae) and LHRW1 (Rhizobium sp.) were selected (based on their zinc solubilizing and PGP activities) for pot scale plant experiments. ZnCO3 was used as zinc source and wheat seedlings were inoculated with these five strains, individually, to assess their effect on plant growth and development. The effect on plants was analyzed based on growth parameters and quantifying zinc content of shoot, root and grains using atomic absorption spectroscopy. Plant experiment was performed in two sets. For first set of plant experiments (harvested after 1 month), maximum shoot and root dry weights and shoot lengths were noted for the plants inoculated with Rhizobium sp. (LHRW1) while E. cloacae (PBS 2) increased both shoot and root lengths. Highest zinc content was found in shoots of E. cloacae (PBS 2) and in roots of P. agglomerans (EPS 13) followed by zinc supplemented control. For second set of plant experiment, when plants were harvested after three months, Pantoea dispersa (EPS 6), P. agglomerans (EPS 13) and E. cloacae (PBS 2) significantly increased shoot dry weights. However, significant increase in root dry weights and maximum zinc content was recorded for Pseudomonas fragi (EPS 1) inoculated plants, isolated from wheat rhizosphere. While maximum zinc content for roots was quantified in the control plants indicating the plant's inability to transport zinc to grains, supporting accelerated bioavailability of zinc to plant grains with zinc solubilizing rhizobacteria.

Zinc has emerged as the most widespread micronutrient deficiency in soils and crops worldwide, resulting in severe yield losses and nutritional quality. Almost half of the soils in the world are deficient in zinc. Since cereal grains have inherently low concentrations, growing these on the potentially zinc-deficient soils further decreases grain zinc concentration. There is a high degree of correlation between zinc deficiency in soils and that in human beings. Zinc is an essential nutrient for human health. There is no life without zinc. Zinc deficiency is the fifth leading cause of death and disease in the developing world. According to the World Health Organization (WHO), about 800,000 people die annually due to zinc deficiency, of which 450,000 are children under the age of five. About one-third of the world’s population suffers from zinc deficiency. The paper describes the role of zinc in crop production as well as human health. It highlights the initiatives of the International Zinc Association in addressing zinc deficiency in soils, crops and humans through increased use of zinc fertilisers.

The relationships of seven levels of zinc supply to dry matter and zinc concentration were assessed for jarrah (Eucalyptus marginata Donn ex Smith) seedlings grown for 84 days in a zinc-deficient sand in the glasshouse. Zinc deficiency symptoms appeared within 28 days of sowing as a change in leaf colour of young leaves from green to bronze. Later, red areas developed and these became necrotic in severe cases. These symptoms were accompanied by decreased shoot and root dry weights. Zinc concentrations in various plant parts were low and, with the exception of the shoot apex, showed little response to zinc supply. Concentrations at the shoot apex varied from 3�g/g in deficient plants to 12�g/g in plants with adequate zinc supply. We suggest that of the plant parts analysed, the shoot apex is the only one which may be useful in defining zinc status of jarrah seedlings. Critical zinc concentration for this tissue was between 10 and 12 �g/g dry matter. Phosphorus concentrations in all plant parts, except the shoot apex, increased to very high levels with increasing zinc deficiency. It is suggested that some zinc deficiency symptoms of jarrah seedlings, e.g. necrosis, may have resulted from phosphorus accumulation due to zinc deficiency.

The article presents the results of experimental studies of the influence of zinc on the thymus gland functioning as the factor of non-specific immune defense of the organism. It has been determined that the development of the immune response is slowed down significantly in animals with thymus gland removal, because thymus gland is the central organ of the immune system and it products not only cytokines but also performs endocrine functions with the production of specific hormones, the amount of which may vary rhythmically. The aim of the study was to establish the relationship between the development of zinc deficiency in the body of animals due to dietary intake with selective zinc exclusion, and the thymus gland mass, level of leukocytes, lymphocytes and the activity of zinc-dependent enzymes in the blood. Taking into account age-related changes in endocrine activity of animals, for the objective evaluation of the thymus gland function in the experiment white non-breeding male rats 3-4 months of age weighing 180-200 g were used, with the most active period of the gland function, which were kept on the zinc deficient diet according to G. Babenko’s method. The analysis of the results shows the development of zinc deficiency in the body, that is set based on the research. The daily amount of zinc for diet consumed and the amount of zinc excreted were identified every 5 days within a month. At the same time, we determined the thymus gland mass, the number of leukocytes, lymphocytes and zinc-dependent enzymes. The received data indicate on the correlation between these parameters. It has been found out that the development of zinc deficiency in the body was accompanied by a gradual adequate decrease of the mass of the thymus gland and the content of leukocytes, lymphocytes and zinc-dependent enzymes activity. Experiments indicate that zinc is one of the active modulators of the cell-mediated immune response. The development of zinc deficiency causes a violation of the reaction of cellular and humoral immunity, which is closely related to the thymus gland function.

Essential vitamins, proteins, and microelements are provided by nutrition, but inadequate and nutrient-poor diets can lead to hidden hunger. Zinc deficiency is a significant hidden resource that affects multiple bodily functions, including immune system function, growth, and development. The primary reasons for the prevalence of zinc deficiency in humans are grain-based products with low concentrations and low zinc solubility in the soil. Intensifying plant production and the inability to replace nutrients absorbed in excess from the soil leads to zinc deficiency in the soil. Consequently, substantial reductions in crop yields are observed, along with decreased zinc concentrations in harvested grains. A number of unsustainable strategies, including expensive medical supplements and zinc-enriched flour-based products to address zinc deficiency, are temporary solutions. Additionally, one such strategy is agronomic biofortification, which recommends utilizing water-soluble zinc fertilizers to increase the concentration of zinc in the plant and soil. A more sustainable and cost-effective approach involves employing traditional plant breeding and molecular techniques to develop new zinc-biofortified cultivars. By enriching wheat with zinc, it absorbs 20-40% more zinc from the soil. Here, this paper will discuss the role of zinc deficiency in wheat and soil and its impact on both crop yield and human nutrition, with a particular emphasis on biofortified wheat.

Patients undergoing hemodialysis often require zinc supplementation owing to hypozincemia, which may reduce serum copper concentrations. However, hypoxia-inducible factor–prolyl hydroxylase inhibitors (HIF-PHIs), which are used to treat renal anemia, have been reported to increase serum copper. Therefore, this study investigates the effectiveness of a combination of HIF-PHIs and zinc for the stabilization of serum copper and zinc concentrations during zinc supplementation for patients undergoing hemodialysis with renal anemia and hypozincemia. The serum zinc and copper concentrations were retrospectively compared over an 8-month period in 20 patients being administered roxadustat (an HIF-PHI) and 20 controls. The changes in concentrations were tracked in participants taking roxadustat who initiated or increased zinc supplementation. The serum zinc concentrations of the participants were significantly higher (p < 0.001) during zinc supplementation, regardless of roxadustat administration. Post-roxadustat, the serum copper concentrations were significantly higher than those pre-roxadustat or in non-roxadustat-treated participants, irrespective of zinc supplementation (p < 0.005). Even post-roxadustat, the serum copper concentrations were significantly lower, with no increase during zinc supplementation (p < 0.040). When zinc supplementation was initiated or increased in participants taking roxadustat, copper and zinc concentrations were normalized. Thus, combining zinc supplementation with roxadustat prevents both an excessive increase in serum copper and a decrease in serum zinc.

Background: Zinc is an essential trace element that is crucial for numerous biological processes, including protein synthesis, antioxidant activity, and bone calcification. Preterm infants are at high risk of zinc deficiency owing to inadequate zinc stores at birth and the rapid decline in zinc concentration in breast milk. This study aimed to evaluate the relationship between zinc concentrations in breast milk and zinc supplementation in preterm infants. Methods: A prospective observational study was conducted at Showa University Hospital, enrolling preterm infants born at less than 32 weeks of gestation or with a birth weight of less than 1800 g. Serum zinc levels, breast milk zinc concentrations, and zinc acetate supplementation were analyzed. Results: The results indicated an inverse correlation between breast milk zinc concentration and the required zinc supplementation dose. Infants receiving high-dose zinc supplementation (≥3 mg/kg/day) had significantly lower breast milk zinc concentrations at 2, 4, and 5 weeks postpartum. Conclusions: These findings highlight the need for individualized zinc monitoring and supplementation strategies to prevent zinc deficiency in preterm infants. Considering the absence of zinc in human milk fortifiers in Japan, aggressive zinc supplementation may be necessary to ensure optimal growth and development.

Global efforts to combat micronutrient deficiencies have often focused on assessing nutrient intakes and supplies(1,2), yet no studies have explored the role of crop selection and land suitability to tackle these deficiencies. This study aims to bridge this gap using existing estimates of global prevalence of iron(3) and zinc(4) deficiencies to identify crops with the highest potential to mitigate these deficiencies. Using the USDA food composition database, we established nutrient profiles for 37 widely cultivated crops, focusing on their iron and zinc content per 100 grams. To evaluate these crops’ effectiveness to meet nutrient requirements, we compared compositions to Harmonized Average Requirements (H-ARs) for women of reproductive age (WRA), a group particularly vulnerable to micronutrient deficiencies. The H-ARs account for variations in nutrient absorption and bioavailability(5). For each crop, we calculated the percentage of the H-AR met by 100 grams of iron and zinc content. This percentage was adjusted for the global prevalence of iron and zinc deficiencies by introducing deficiency weighting—multiplying each crop’s nutrient contributions by the global prevalence of iron and zinc deficiencies. The result was a deficiency-weighted nutrient score for each crop. Soybeans scored highest at 61.67, followed by cowpeas (50.30), pearl millet (33.69), and Phaseolus beans (31.33), indicating their strong potential to address global iron and zinc deficiencies. Next, we integrated these nutrient scores with global land suitability and yield potential data from the Global Agro-Ecological Zones (GAEZ) database to map regions most suited for growing these nutrient-dense crops. On average, our findings show that Tonga is the most suitable country for soybean cultivation, with a potential yield of 3.77 tons per hectare (tons/ha), Uruguay for cowpeas (2.82 tons/ha), Lithuania for Phaseolus beans (3.93 tons/ha), and Guinea-Bissau for pearl millet (3.87 tons/ha). Through multivariate clustering, we linked global deficiency patterns with yield potential across various regions. Countries such as those in the Caribbean, Eastern, Western, and Middle Africa, and Southern and Southeastern Asia emerged as priority regions where the production of these crops would be most beneficial to combat iron and zinc deficiencies. The results provide valuable insights to align agricultural land use practice with nutritional requirements, particularly in regions with high iron and zinc deficiency prevalence.

Zinc Supplementation Prevents Alcoholic Liver Injury in Mice through Attenuation of Oxidative Stress