Wheat Grain Zn Research Articles

Uptake of zinc from the soil to the wheat grain: Nonlinear process prediction based on artificial neural network and geochemical data

Trace elements in plants primarily derive from soils, subsequently influencing human health through the food chain. Therefore, it is essential to understand the relationship of trace elements between plants and soils. Since trace elements from soils absorbed by plants is a nonlinear process, traditional multiple linear regression (MLR) models failed to provide accurate predictions. Zinc (Zn) was chosen as the objective element in this case. Using soil geochemical data, artificial neural networks (ANN) were utilized to develop predictive models that accurately estimated Zn content within wheat grains. A total of 4036 topsoil samples and 73 paired rhizosphere soil-wheat samples were collected for the simulation study. Through Pearson correlation analysis, the total content of elements (TCEs) of Fe, Mn, Zn, and P, as well as the available content of elements (ACEs) of B, Mo, N, and Fe, were significantly correlated with the Zn bioaccumulation factor (BAF). Upon comparison, ANN models outperformed MLR models in terms of prediction accuracy. Notably, the predictive performance using ACEs as input factors was better than that using TCEs. To improve the accuracy, a two-step model was established through multiple testing. Firstly, ACEs in the soil were predicted using TCEs and properties of the rhizosphere soil as input factors. Secondly, the Zn BAF in grains was predicted using ACE as input factors. Consequently, the content of Zn in wheat grains corresponding to 4036 topsoil samples was predicted. Results showed that 85.69 % of the land was suitable for cultivating Zn-rich wheat. This finding offers a more accurate method to predict the uptake of trace elements from soils to grains, which helps to warn about abnormal levels in grains and prevent potential health risks.

Agronomy biofortification of wheat grain in a saline and calcareous soil

Agronomy biofortification is an important crop management strategy to enhance concentrations of micronutrients in edible portions. The availability of micronutrients for plant uptake is reduced by the high salinity, pH, and lime of soils. Hence, this study aimed to determine the most appropriate time and the best ratio of zinc (Zn) and iron (Fe) consumption during the wheat growth stages in a saline and calcareous soil. The experiment consisted of two factors with four levels; 0, 30, 60, and 120 kg Zn ha−1 as Zn0, Zn1, Zn2, and Zn3 respectively, and 0, 2.5, 5, and 7.5 kg Fe ha−1 as Fe0, Fe1, Fe2, and Fe3 respectively, in a randomized complete block design with four replications. The results showed that the interaction effects of Fe and Zn fertilizers application were significant on the wheat yield indices and concentration of Fe and Zn in wheat shoots and grain. The simultaneous application of 120 kg Zn ha−1 and 5 kg Fe ha−1 caused significant improvement (p < 0.05) in thousand kernel weight (9.1%) and subsequently grain yield (23.4%) compared to the control treatment. The Zn concentration in the wheat shoot during tillering (37.0–58.2 mg Zn kg−1) was higher than the other two growth stages (elongation (29.2–40.8 mg Zn kg−1) and booting (20.0–31.0 mg Zn kg−1)). While the highest Fe concentration in wheat shoots was observed at the stem elongation stage (98.5–268.8 mg Fe kg−1), then the booting stage (91.0–150.8 mg Fe kg−1) and finally the least absorption was at the tillering (80.0–120.0 mg Fe kg−1). Because of the high calcium carbonate, salinity and Zn- deficient soil of the experimental site, the Zn concentration in wheat grain was obtained in a range of 3 to 19 mg kg−1. The results clarified that the fertilizer application of 30 kg Zn ha−1 and 2.5 kg Fe ha−1 can be proportionally and simultaneously increased the concentration of Fe and Zn in wheat grain by 100%. Therefore, the soil application of 30 kg Zn and 2.5 kg Fe per hectare proposed for improvement in quantitative (619 kg ha−1 increase in wheat grain yield) and qualities (100% increase in grain Zn and Fe concentration and 8% increase in thousand kernel weight) indices of wheat yield in calcareous and saline soils.

Genomic Advances in Biofortification of Iron and Zinc in Wheat (Triticum aestivum L.)

Majority of population that depend on wheat are found to be deficient in iron and zinc. About 20% of calories worldwide are derived from wheat. Milling of wheat reduces the bioavaibility of Fe and Zn in wheat grains. Micronutrient deficiency is the main cause of malnutrition worldwide and hidden hunger in underdeveloped countries. To overcome this problem it becomes necessary to develop varieties that are rich in iron and zinc content. Biofortification gets around these issues by enhancing the micronutrient content of wheat. The genetic approaches of biofortification particularly the non-conventional methods have proved to be the most efficient ones. These method includes QTL mapping approach, GWAS and transgenics. Although conventional methods for a long time has been used for developing varieties of wheat rich in Fe and Zn but conventional breeding for certain traits may be inconvenient and time-consuming and are prone to errors due to their reliance on traditional phenotyping or visual assessments. Several research have been undertaken to map QTLs of Fe and Zn concentration in wheat grains and have been used in elite genetic backgrounds to improve micronutrient content. Genomic studies revealed through GWAS exhibit high QTL resolution and allele coverage, which can be used for improvement of Fe and Zn content in wheat. Genetic engineering techniques or transgenics approaches allows genetic alteration of crops to improve the nutritional quality of wheat. Genomic approach of biofortification of wheat has proved to be the most efficient methods for increasing iron and zinc content in the crop.

Specific bacterial communities in the rhizosphere of low-cadmium and high‑zinc wheat (Triticum aestivum L.)

Microorganisms can modulate the contents of cadmium (Cd) and zinc (Zn) in wheat grains. Increasing the essential nutrient element Zn and decreasing the toxic element Cd in wheat grains can significantly improve human health. To characterize the specific bacterial communities associated with Cd and Zn accumulation in wheat, we conducted a field experiment by planting wheat cultivars differing in their capacity for Cd and Zn accumulation. The grain Cd contents in wheat cultivars YN23 (0.078 mg kg−1), JN17 (0.080 mg kg−1), YN836 (0.081 mg kg−1) and LM2 (0.091 mg kg−1) were significantly lower than those in ZM32 (0.16 mg kg−1). The Zn contents were significantly higher in the grains of JN17 (44.36 mg kg−1), LM2 (42.22 mg kg−1) and ZM32 (43.19 mg kg−1) than YN23 (27.05 mg kg−1) and YN836 (29.70 mg kg−1). On the basis of contents and bio-concentration factors of Cd and Zn in wheat grain, JN17 and LM2 were identified as low-Cd- and high-Zn-accumulating cultivars, YN23 and YN836 were low-Cd- and low-Zn-accumulating cultivars, and ZM23 was a high-Cd- and high-Zn-accumulating cultivar. The relative abundance values of Gemmatimonadaceae, Sphingomonadaceae and Beijerinckiaceae in the rhizospheres of low-Cd cultivars were significantly higher than those of high-Cd cultivars. High-Zn cultivars had higher abundance of Rhodanobacteraceae in the rhizosphere than did low-Zn cultivars. The low-Cd- and high-Zn-accumulating cultivars were enriched in Alphaproteobacteria and Gemmatimonadaceae, and strengthened nitrification function including aerobic_ammonia_oxidation and aerobic_nitrite_oxidation in the rhizosphere soil, thus contributing to the decreased Cd and increased Zn contents in wheat grains. Microbial technology is a promising method to control the contents of Cd and Zn in wheat grains.

Agronomic Biofortification of Zinc in Wheat

Intensive cropping system with imbalance use of fertilizers are responsible for declining soil health, underground water table, declining land and water productivity, emergence of new micronutrient deficiencies, new weed flora, and resistance to herbicides especially in emerging countries. This is further intensified when micronutrients particularly zinc (Zn), which is essential for human health, particularly in developing countries. Zn biofortification is a strategy for improving the intrinsic Zn content of the edible portion of plants via application of Zn-enriched fertilizers to soil or by foliar application at a predetermined stage and a proper dose. The most common cereal in the human diet is wheat, which make it most suitable targets for agronomic biofortification. The concentration of Zn in wheat grain is genotype-dependent and interacts with the environment, causing variation in micronutrient concentrations. Given Zn's importance in cereal-based nutrition, zinc biofortification seems to to be an innovative technology for alleviating zinc deficiency in human health, particularly on the Indian subcontinent, by applying Zn as a foliar or soil application.

The Role of Balanced Fertilization on the Reduction of Phytic Acid to Zinc Molar Ratio (PA/Zn) in the Irrigated and Rainfed Wheat Fields on the Calcareous Soils of Iran

One of the most important quality factors in the wheat grain, which directly affects the quality of the bread, is the molar ratio of phytic acid to zinc (PA/ Zn) index. In order to evaluate the role of balanced fertilization on increasing the yield, quality, and reducing PA/Zn in wheat grain (Triticum aestivum L.), the first experiment was implemented with two fertilizer treatments (Farmer’s conventional fertilization practice, i.e. NP-fertilizers) and the optimum use of fertilizers (fertilization was on the basis of soil test results) in three different irrigated farms in Mianeh, East Azarbaijan province and the second experiment was carried out in 10 different dryland farms on the outskirts of the Khodabandeh, Zanjan Province in 2010-2011 growing season with an average of 380 mm annual rainfall. This experiment had three treatments, i.e. T1=Control (no fertilizer); T2=Farmer’s conventional fertilization practice (NP-fertilizers), and T3=Fertilization based on soil test values (Optimum use of fertilizers) in four replications with a randomized complete block design. The wheat cultivar in the irrigated farms was Alvand and in the rainfed farms was Azar-2. Protein, phytic acid, phosphorus (P), potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and Zinc (Zn) in wheat grains were analyzed according to the standard methods. The collected data were analyzed by using a t-test and SAS Software. The results revealed that in the irrigated wheat fields, the optimal use of fertilizers increased the grain yield up to 27 percent, protein content, all micronutrients especially Zn significantly, but it decreased PA/Zn molar ratio significantly in comparison to Farmer’s conventional fertilization practice. While phytic acid concentration in the control plots was 8.70, it decreased up to 7.41gkg-1, Zn concentration was increased from 29 to 43 mgkg-1 and subsequently, PA/Zn molar ratio was reduced from 30 to 17. The statistical analysis showed a significant difference for phytic acid, Zn, and PA/Zn molar ratio in all wheat farms in the second experiment, the results demonstrated that while the average grain yield in T1 was 975kgha-1, it has increased up to 1401kgha-1 in T2 and over 1628kgha-1, respectively. The average yield increase was significant at the 5% level despite the existing drought situation in the fall of 2010. The mean concentration of P and Zn in wheat grains in the control plots were 0.26 percent and 21mgkg-1, in Farmer’s conventional fertilization practice were 0.24 percent and 25mgkg-1 and in the fertilization based on soil test values were 0.21 percent and 30mgkg-1, respectively and they were significant in the 5% level. While PA/Zn in the control plots was 29, it has been decreased to 22 in T2 and to 15 in T3 plots, respectively. Comparison between PA/Zn molar ratios revealed that due to the existing water during the growing season in the irrigated fields, the availability of all nutrients including Zn was slightly higher, but in drylands, the amount and distribution of rainfall is much important and it is clear that by increasing the amount and distribution of rainfall during the growing season, more grain yield and lower PA/Zn molar ratio is expected. It is obvious that these variations are widely dependent on climate change, cultivars, and management factors. This project is recommended to be continued at least in the wheat-grown provinces all over the Iran.

The Role of Balanced Fertilization on the Reduction of Phytic Acid to Zinc Molar Ratio (PA/Zn) in the Irrigated and Rainfed Wheat Fields on the Calcareous Soils of Iran

One of the most important quality factors in the wheat grain, which directly affects the quality of the bread, is the molar ratio of phytic acid to zinc (PA/ Zn) index. In order to evaluate the role of balanced fertilization on increasing the yield, quality, and reducing PA/Zn in wheat grain (Triticum aestivum L.), the first experiment was implemented with two fertilizer treatments (Farmer’s conventional fertilization practice, i.e. NP-fertilizers) and the optimum use of fertilizers (fertilization was on the basis of soil test results) in three different irrigated farms in Mianeh, East Azarbaijan province and the second experiment was carried out in 10 different dryland farms on the outskirts of the Khodabandeh, Zanjan Province in 2010-2011 growing season with an average of 380 mm annual rainfall. This experiment had three treatments, i.e. T1=Control (no fertilizer); T2=Farmer’s conventional fertilization practice (NP-fertilizers), and T3=Fertilization based on soil test values (Optimum use of fertilizers) in four replications with a randomized complete block design. The wheat cultivar in the irrigated farms was Alvand and in the rainfed farms was Azar-2. Protein, phytic acid, phosphorus (P), potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and Zinc (Zn) in wheat grains were analyzed according to the standard methods. The collected data were analyzed by using a t-test and SAS Software. The results revealed that in the irrigated wheat fields, the optimal use of fertilizers increased the grain yield up to 27 percent, protein content, all micronutrients especially Zn significantly, but it decreased PA/Zn molar ratio significantly in comparison to Farmer’s conventional fertilization practice. While phytic acid concentration in the control plots was 8.70, it decreased up to 7.41gkg-1, Zn concentration was increased from 29 to 43 mgkg-1 and subsequently, PA/Zn molar ratio was reduced from 30 to 17. The statistical analysis showed a significant difference for phytic acid, Zn, and PA/Zn molar ratio in all wheat farms in the second experiment, the results demonstrated that while the average grain yield in T1 was 975kgha-1, it has increased up to 1401kgha-1 in T2 and over 1628kgha-1, respectively. The average yield increase was significant at the 5% level despite the existing drought situation in the fall of 2010. The mean concentration of P and Zn in wheat grains in the control plots were 0.26 percent and 21mgkg-1, in Farmer’s conventional fertilization practice were 0.24 percent and 25mgkg-1 and in the fertilization based on soil test values were 0.21 percent and 30mgkg-1, respectively and they were significant in the 5% level. While PA/Zn in the control plots was 29, it has been decreased to 22 in T2 and to 15 in T3 plots, respectively. Comparison between PA/Zn molar ratios revealed that due to the existing water during the growing season in the irrigated fields, the availability of all nutrients including Zn was slightly higher, but in drylands, the amount and distribution of rainfall is much important and it is clear that by increasing the amount and distribution of rainfall during the growing season, more grain yield and lower PA/Zn molar ratio is expected. It is obvious that these variations are widely dependent on climate change, cultivars, and management factors. This project is recommended to be continued at least in the wheat-grown provinces all over the Iran.

Genetic biofortification of wheat with zinc: Opportunities to fine-tune zinc uptake, transport and grain loading.

Zinc (Zn) is an important micronutrient in the human body, and health complications associated with insufficient dietary intake of Zn can be overcome by increasing the bioavailable concentrations in edible parts of crops (biofortification). Wheat (Triticum aestivum L) is the most consumed cereal crop in the world; therefore, it is an excellent target for Zn biofortification programs. Knowledge of the physiological and molecular processes that regulate Zn concentration in the wheat grain is restricted, inhibiting the success of genetic Zn biofortification programs. This review helps break this nexus by advancing understanding of those processes, including speciation regulated uptake, root to shoot transport, remobilisation, grain loading and distribution of Zn in wheat grain. Furthermore, new insights to genetic Zn biofortification of wheat are discussed, and where data are limited, we draw upon information for other cereals and Fe distribution. We identify the loading and distribution of Zn in grain as major bottlenecks for biofortification, recognising anatomical barriers in the vascular region at the base of the grain, and physiological and molecular restrictions localised in the crease region as major limitations. Movement of Zn from the endosperm cavity into the modified aleurone, aleurone and then to the endosperm is mainly regulated by ZIP and YSL transporters. Zn complexation with phytic acid in the aleurone limits Zn mobility into the endosperm. These insights, together with synchrotron-X-ray-fluorescence microscopy, support the hypothesis that a focus on the mechanisms of Zn loading into the grain will provide new opportunities for Zn biofortification of wheat.

Concentration and Localization of Fe and Zn in Wheat Grain as Affected by Its Application to Soil and Foliage.

Nutritional status of people can be improved by enhancing zinc (Zn) and iron (Fe) content in cereals used as staple mainly in poor resource countries. Zinc and Fe were applied through soil and foliage in a study to biofortify wheat grains. Foliar application of both micronutrients increased the growth and grain vigor as compared to soil application and control. Also, foliar application significantly enhanced Zn and Fe concentration in grain pre-dominantly localized in aleurone layer. Exogeneous application of Fe and Zn was found beneficial for plant growth and enhanced Fe and Zn concentrations in grain, however aleurone layer and embryonic region of the grain showed higher accumulations than that in endosperm. Therefore, understanding of physiological and molecular pathways for uptake and localization of Fe and Zn in wheat grains need to be critically examined to improve their concentration in grain to achieve the biofortification targets.

Zinc in Wheat Grain, Processing, and Food.

Improving zinc (Zn) content in wheat and its processed foods is an effective way to solve human Zn deficiency, which can cause a variety of diseases. This article summarizes the works on Zn in wheat grain, wheat processing, and wheat-derived foods. Grain Zn content in wheat was 31.84 mg·kg−1 globally but varied across continents, for example, 25.10 mg·kg−1 in Europe, 29.00 mg·kg−1 in Africa, 33.63 mg·kg−1 in Asia, and 33.91 mg·kg−1 in North America. Grain Zn content in wheat improved from 28.96 to 36.61 mg·kg−1 and that in flour increased from 10.51 to 14.82 mg·kg−1 after Zn fortification. Furthermore, Zn content varied in the different processed components of wheat; that is, Zn content was 12.58 mg·kg−1 in flour, 70.49 mg·kg−1 in shorts, and 86.45 mg·kg−1 in bran. Zinc content was also different in wheat-derived foods, such as 13.65 mg·kg−1 in baked food, 10.65 mg·kg−1 in fried food, and 8.03 mg·kg−1 in cooking food. Therefore, the suitable Zn fortification, appropriate processing, and food type of wheat are important to meet people's Zn requirement through wheat.

Zinc Biofortification in the Grains of Two Wheat (Triticum aestivum L.) Varieties Through Fertilization

We examined the effects of zinc (Zn) fertilization on wheat, focusing on yield and biofortification in the grains of two wheat varieties. Five Zn rates, i.e., 0, 1.5, 3.0, 4.5, and 6.0 kg ha&lt;sup&gt;−1&lt;/sup&gt; applied as ZnSO&lt;sub&gt;4&lt;/sub&gt;·7H&lt;sub&gt;2&lt;/sub&gt;O (23% Zn), and two wheat varieties, i.e., ‘BARI Gom-25’ and ‘BARI Gom-26,’ were used in the study. All plant characteristics, except 1,000-grain weight and plant height, i.e., tillers plant&lt;sup&gt;−1&lt;/sup&gt;, spikes m&lt;sup&gt;−2&lt;/sup&gt;, spike length, spikelets spike&lt;sup&gt;−1&lt;/sup&gt;, and grains spike&lt;sup&gt;−1&lt;/sup&gt;, were significantly influenced by Zn fertilization. Treatment with 3.0 kg Zn ha&lt;sup&gt;−1&lt;/sup&gt; (Zn&lt;sub&gt;3.0&lt;/sub&gt;) produced the highest grain yield (3.90 t ha&lt;sup&gt;−1&lt;/sup&gt;), which was statistically similar to Zn&lt;sub&gt;4.5&lt;/sub&gt; and Zn&lt;sub&gt;6.0&lt;/sub&gt; treatments. The control treatment (Zn&lt;sub&gt;0&lt;/sub&gt;) produced the lowest grain yield (2.99 t ha&lt;sup&gt;−1&lt;/sup&gt;). The concentrations of N, Zn, and Fe were significantly and positively influenced by Zn treatment. The crop varieties did not differ significantly in terms of N and Zn concentrations. However, the grain Fe concentration was remarkably higher in ‘BARI Gom-26’ than in ‘BARI Gom-25.’ The grain N and protein concentrations increased linearly with the Zn application rate. The grain Zn concentration increased with Zn application rates in a quadratic line, indicating that the concentration of Zn in wheat grain increased with Zn fertilization; however, it attained a maximum value in the Zn&lt;sub&gt;4.5&lt;/sub&gt; treatment, after which it declined with higher rate of Zn application. The application of Zn at the rate of 4.5 kg ha&lt;sup&gt;−1&lt;/sup&gt; resulted in the highest Zn fortification (39.7 µg g&lt;sup&gt;−1&lt;/sup&gt;) in wheat grains, which was 17.1% higher than in the control treatment. The response curve showed that 4.62 kg ha&lt;sup&gt;−1&lt;/sup&gt; for ‘BARI Gom-25’ and 3.94 kg ha&lt;sup&gt;−1&lt;/sup&gt; for ‘BARI Gom-26’ were the optimum Zn rates for achieving higher wheat grain yield. However, 5.5 kg ha&lt;sup&gt;−1&lt;/sup&gt; was the optimum Zn rate for obtaining higher Zn fortification in wheat grains.

Zinc status and its requirement by rural adults consuming wheat from control or zinc-treated fields.

Human zinc (Zn) deficiency is prevalent in areas where cereals dominate in the diet. Soil Zn application may enhance the concentration of Zn in wheat grains and dietary Zn intake by target populations. However, its value has never been practically quantified in Zn nutrition of any population group. We, therefore, studied farming families in rural Punjab (Pakistan). The selected adults (n = 156, grouped based on age and gender) were Zn undernourished (as assessed by estimated Zn bioavailability in their diet) and their plasma Zn levels also indicated Zn deficiency. On average, wheat consumption by the adults contributed about 68% in total Zn and 93% in total phytate intakes. Soil Zn application to wheat fields significantly increased Zn and decreased phytate concentration in chapati (flatbread made of whole-wheat flour). From dietary phytate intakes by the adults, we calculated desired chapati Zn concentration and dietary Zn intake that would meet their daily Zn requirement. The physiological Zn requirements of adult women and men were estimated to be achieved by intake of, respectively, 10.4-15.3mgZnd-1 (37-46mg Zn kg-1 in chapati) and 14.4-23.3mgZnd-1 (41-52mg Zn kg-1 in chapati). It was evident that soil Zn application aiming at optimum grain yield of wheat significantly improved Zn nutrition of the studied adults, but not up to desired levels. High Zn applications (via soil and/or foliage) to wheat and growing cultivars specifically selected for Zn biofortification may be needed to optimise Zn nutrition in rural Pakistan.

Mineral Elements Bioavailability in Milling Fractions of Wheat Grain Response to Zinc and Nitrogen Application

A field experiment was conducted in a high‐yield region in North China to estimate the effect of Zn and N fertilization on mineral element distribution and bioavailability in eight milling fractions of wheat grain (Triticum aestivum L.), which included bran, shorts, break (B1, B2, and B3) and reduction (R1, R2, and R3). The results indicated that foliar Zn decreased Ca and Mn concentration in wheat grain averagely by 4.3 and 6.8%, respectively, but increased Zn by 42.6%. Soil N application improved N, Ca, Cu, Fe, and Zn concentration by 38.9, 10.5, 19.95, 7.0, and 24.4%, respectively. All elements, N, P, K, Ca, Mg, Cu, Mn, Fe, and Zn, were mostly located in bran and shorts. Foliar Zn significantly decreased the accumulation of Mn in bran, shorts, and B2, and increased Zn in each fraction, but did not influence the distribution of Mn and Zn among the eight fractions. Nitrogen application increased the accumulation of all elements in shorts, and altered the distribution in wheat grain. Both measures improved the bioavailability of Zn in B3, R1, R2, and reduction, but did not affect that in bran and shorts. Foliar Zn and N application increased total daily absorbed Zn in flour by 66.0 and 48.9%, and grain by 32.0 and 28.4%, respectively. The concentration of N in wheat grains was positively correlated with Ca, Cu, Fe, and Zn. No correlation was found between Zn and Fe concentration. These results are relevant to agronomic management strategies to improve the element nutrition of wheat grain.Core Ideas Foliar Zn decreases Mn accumulation in bran, shorts, and B2 and increased Zn in each fraction. Soil N application increased accumulation of all elements in shorts, Cu, and Fe in bran but decreased P and K in bran fraction. Zinc bioavailability was higher in break and reduction, and improved by foliar Zn and soil N application. Nitrogen concentration was positively correlated with Ca, Cu, Fe, and Zn in wheat grains. Zinc concentration was not correlated with Fe in wheat grains.

Breeding and agronomic approaches for the biofortification of zinc in wheat (Triticum aestivum L.) to combat zinc deficiency in millions of a population: a Bangladesh perspective

The World Health Organization (WHO) has estimated that around 2 billion people across the globe are suffering from “hidden hunger”, where 815 million are under malnutrition. The major essential elements for humans are Fe, Zn, I, Se, Ca, F, and also vitamins. Among them, Zn is considered in the fifth place leading to causes of several deficiency diseases. At least one-third of the population in the world is facing Zn deficiency including around 450,000 children under the age of five. Vitamin A, Fe, and Zn deficiencies can be overcome through the biofortification of staple foodstuffs. This review emphasizes various breeding and agronomic approaches for the biofortification of Zn in wheat grains, which is an encouraging and cost-effective method to enhance the Zn contents of cereal grains. Recently, the Bangladesh Wheat and Maize Research Institute (BWMRI), with technical support from CIMMYT, Mexico, released a promising new Zn-biofortified wheat cultivar, ‘BARI Gom 33’, a result from a conventional breeding program. It has 32 and 50–55 mg kg&lt;sup&gt;−1&lt;/sup&gt; Zn without and with soil application of ZnSO&lt;sub&gt;4&lt;/sub&gt;, respectively. This cultivar could be a savior for a million people in South Asia, including Bangladesh.

Arbuscular mycorrhizal fungi increase both concentrations and bioavilability of Zn in wheat (Triticum aestivum L) grain on Zn-spiked soils

Although winter wheat (Triticum aestivum L) are commonly colonized by arbuscular mycorrhizal fungi (AMF) under field conditions, the effects and related mechanisms of the fungi on concentrations and bioavailability of Zn in grain is still unclear. A pot trial was done to survey the influence of two species of AMF (Funneliformis mosseae BGC HEB02 and Rhizophagus intraradices BGC HEB07D) on grain yield, concentrations of phytic acid and Zn in winter wheat (T. aestivum cv. Xiaoyan22) in Zn-spiked soils under two levels of P application. The present study showed that mycorrhizal inoculation apparently improved P nutrition in wheat and significantly (p < 0.01) increased grain yield, especially under low soil P conditions. Increasing levels of P and Zn in soils significantly (p < 0.01) enhanced phytic acid concentrations in wheat grain, while inoculation of AM fungi had insignificant effect on grain phytic acid concentrations. Grain Zn concentrations under the mycorrhizal treatments were 1.13–2.76 times of those without inoculation, especially for R. intraradices. The present study revealed that concentrations and bioavailability of Zn in wheat grain can be significantly increased by inoculation of AMF, indicating the potential of AMF to cope with Zn deficiency for residents living on wheat as their staple food.

Characterizing bread wheat genotypes of Pakistani origin for grain zinc biofortification potential.

Zinc (Zn) is essential for all life forms and its deficiency is a major issue of malnutrition in humans. This study was carried out to characterize 28 wheat genotypes of Pakistani origin for grain zinc biofortification potential, genetic diversity and relatedness. There was low genetic differentiation among the tested genotypes. However, they differed greatly in yield-related traits, grain mineral (Zn, calcium (Ca) and protein) concentrations and Zn bioavailability. Zinc application increased the concentration of Zn in wheat grain (32.1%), embryo (19.8%), aleurone (47%) and endosperm (23.7%), with an increase in bioavailable Zn (22.2%) and a reduction in phytate concentration (6.8%). Application of Zn also enhanced grain protein and Ca concentrations. Among wheat genotypes, Blue Silver had the highest concentration of Zn in grain, embryo, aleurone and endosperm, with high bioavailable Zn, while Kohinoor-83 had low phytate concentration. Wheat genotypes of Pakistan are genetically less diverse owing to continuous focus on the development of high-yielding varieties only. Therefore genetically diverse wheat genotypes with high endospermic Zn concentration and better grain yield should be used in breeding programs approaches, aiming at improving Zn bioavailability. © 2018 Society of Chemical Industry.

Stabilization of Cd-, Pb-, Cu- and Zn-contaminated calcareous agricultural soil using red mud: a field experiment

Red mud (RM) was used to remediate heavy metal-contaminated soils. Experiments with two different dosages of RM added to soils were carried out in this study. It was found that soil pH increased 0.3 and 0.5 unit with the dosage of 3 and 5% (wt%), respectively. At the dosage of 5%, the highest stabilization efficiencies for Cd, Pb, Cu and Zn reached 67.95, 64.21, 43.73 and 63.73%, respectively. The addition of RM obviously transferred Cd from the exchangeable fraction to the residual fraction. Meanwhile, in comparison with the control (no RM added), it reduced 24.38, 49.20, 19.42 and 8.89% of Cd, Pb, Cu and Zn in wheat grains at the RM addition dosage of 5%, respectively. At the same time, the yield of wheat grains increased 17.81 and 24.66% at the RM addition dosage of 3 and 5%, respectively. Finally, the addition of RM did not change the soil bacterial community. These results indicate that RM has a great potential in stabilizing heavy metals in calcareous agricultural soils.

Effects of source/sink manipulation on grain zinc accumulation by winter wheat genotypes

Agronomy practices aimed at wheat (Triticum aestivum L.) grain Zn biofortification are important to alleviate Zn deficiency in humans, especially for those resource-poor people owing to subsistence on diets dominated by cereal-based foods with low concentrations and bioavailability of Zn. To promote understanding of source-sink flow processes affecting biofortification of wheat with Zn, effects of different source/sink manipulations on grain Zn accumulation by wheat were examined in pot and field at two locations. Treatments included foliar applications of deionized water, sucrose, ZnSO4, sucrose + Zn, defoliation, spike shading or partial removal of spikes. Results showed sucrose + Zn significantly increased grain Zn concentration more than Zn alone. Grain Zn concentration with sucrose + Zn averaged 66 mg kg-1 for ‘Kenong 9204’ and 59 mg kg-1 for ‘Liangxing 99’ in pot, and ranged from 42 to 58 mg kg-1 for ‘Liangxing 99’, ‘Jinan 17’, ‘Jimai 20’, ‘Jimai 22’, and ‘Luyuan 502’ under field, approaching the field-grown target 60 mg kg-1 proposed by World Health Organization. Molar ratios of phytic acid/Zn and phytic acid × Ca/Zn of ‘Jinan 17’, ‘Jimai 20’ or ‘Luyuan 502’ with sucrose + Zn were reduced to be < 15 and < 200, respectively, suggesting higher Zn bioavailability. Defoliation or spike shading decreased grain weight, Zn concentration and content. It is concluded that grain Zn accumulation of wheat can be affected by the source-sink relationship of Zn and/or carbohydrate, and the foliar spray ‘sucrose + Zn’ is recommended for increasing concentration and bioavailability of Zn in wheat grains.

Pseudomonas-aided zinc application improves the productivity and biofortification of bread wheat

Zinc (Zn) deficiency reduces the grain yield and quality of wheat. Plant-growth-promoting bacteria may help to improve plant Zn availability. This study evaluated the influence of inorganic Zn, with and without Zn-solubilising bacteria (Pseudomonas sp. MN12), on performance and grain biofortification of wheat. Zinc was supplied with and without Pseudomonas to two bread wheat (Triticum aestivum L.) cultivars (Lasani-2008 and Faisalabad-2008) via four treatments: soil application (5.0 mg kg–1 soil), foliar application (0.025 m), seed priming (0.5 m) and seed coating (1.25 g kg–1 seed). Hydroprimed seeds were taken as control. Inoculation with Pseudomonas improved photosynthesis, yield, biofortification of grains and organic acid production in root exudates. However, inoculation was more effective when applied in combination with different Zn application methods. Maximum improvement in plant photosynthetic assessment and grain yield was recorded with Pseudomonas + Zn seed priming, followed by Pseudomonas + soil application of Zn. These two combinations also enhanced organic acid production in root exudates of wheat. Soil and foliar application of Zn with Pseudomonas enhanced Zn concentration in whole grain, embryo, aleurone and endosperm. Combined application of Pseudomonas and Zn (soil and foliar) reduced phytate concentration and [phytate] : [Zn] ratio and increased the bioavailable Zn in wheat grain compared with the control. In conclusion, the combination Pseudomonas inoculation along with Zn seed priming and soil application was more effective in improving grain yield of wheat, whereas soil- and foliar-applied Zn with Pseudomonas inoculation was better in enhancing grain Zn concentration and bioavailability.

Synergistic use of nitrogen and zinc to bio-fortify zinc in wheat grains

Our daily diet is largely contributed by cereals, which have low genetic abilities to amass higher concentrations of micronutrients in their grains. Hence, wide spread deficiencies iron, zinc and other essential nutrients have prevailed. Present study focuses the bio-fortification of Zn in wheat grains, taking advantage of nutrient-nutrient synergy between Zn and N. Three wheat genotypes (NIA-Amber, BWQ-4 and SD-998) were tested in a field experiment following randomized complete block factorial design with three replicates. Urea fertilizer was applied at the rates of 120 (recommended), 150 and 180 kg N ha -1 in combination with three levels of Zn (0, 5 & 10 kg ha -1 ). Outcomes of the experiment revealed that NIA-Amber had the highest grain yield of 6.03 tons/ha against 150 kg N ha -1 and 10 kg Zn ha -1 . Maximum Zn contents of 447.86, 429.56 and 395.56 g ha -1 were observed in BWQ-4, SD-998 and NIA-Amber at 180 kg N ha -1 in combination with 10 kg Zn ha -1 . Maximum enhancement in protein contents was observed in BWQ-4 (743 kg ha -1 ) at 180 kg N ha -1 and combined with 5 kg Zn ha -1 . For NIA-Amber, 180 kg N ha -1 in combination of 10 kg Zn ha -1 proved the most suitable in terms of Zn concentration and other quality attributes. Nitrogen @ 180 kg N ha -1 with 5 kg Zn ha -1 depicted appreciable zinc and protein contents in grains of BWQ-4 and SD-998.