Foliar Zn Research Articles

Improving nutritional values and yield in common bean (Phaseolus vulgaris L.) cultivars via foliar application of zinc and iron fertilizers

AbstractDeveloping countries struggle to achieve food security due to a lack of superior crop cultivars, limited inputs, and environmental degradation. One way to deal with these issues is to biofortify with zinc‐ (Zn) and iron (Fe)‐containing fertilizers to improve nutrient content and productivity. Thus, this study aims to assess the effect of foliar application of Zn and Fe fertilizers on various bean cultivars. Three cultivars (SAB‐632, DAB‐197, and BZ‐2) combined with nine Zn‐ and Fe‐containing fertilizers (T1 = 0, T2 = 0+1.5%, T3 = 0+3%, T4 = 0.5%+0, T5 = 0.5%+1.5%, T6 = 0.5%+3%, T7 = 1%+0, T8 = 1%+1.5%, and T9 = 1%+3%) were used as experimental treatments. The study utilized a split‐plot design with a factorial arrangement and three replications, with cultivars on the main plot and fertilizer treatments on the sub‐plots. The result revealed that T8 with the cultivar SAB‐632 had a significantly higher (17.2%) grain Zn concentration than the control. The cultivar SAB‐632 exhibited significantly higher Zn and Fe accumulations. Grain Zn and Fe accumulation were significantly enhanced by the foliar application of treatments, either individually or combined. T6 showed the highest accumulation of Zn and Fe, followed by T9. These values were increased by 33.4% and 29.2%, respectively, due to T6 compared to the control treatment. Additionally, applying these treatments to the leaves improved most agronomic parameters. Therefore, using foliar Zn + Fe fertilizers in bean cultivation can increase essential nutrient contents in grains and improve productivity, ensuring food security and nutrition for small‐scale farmers.

Variation of grain zinc, phytate concentration and phytate : Zn molar ratio in unpolished and polished rice affected by foliar zinc application among Thai rice varieties

ABSTRACT This study evaluated the variation in grain yield and Zn concentration in rice after foliar application of Zn and the impact on its phytate : Zn molar ratio among 21 rice varieties. Rice varieties were grown under field conditions using a randomized complete block design with four replications over two cropping years in 2020 and 2021 during the rainy season. Foliar Zn application varied grain yield from −26.0 to 13.6% in 2020 and −14.7 to 30.4% in 2021 compared with non-foliar Zn. Grain Zn was varied from 0.5 to 31.1% in 2020 and from −5.9 to 47.8% in 2021 in unpolished rice and from 9.4 to 47.0% in 2020 and from 8.2 to 163.0% in 2021 in polished rice. The phytate : Zn molar ratio was decreased when foliar Zn was applied to the unpolished and polished rice, with a lower ratio in the polished rice. The phytate : Zn molar ratio decreased exponentially with increasing grain Zn concentration in the unpolished rice, while decreasing linearly with increasing grain Zn concentration in the polished rice. The results of this study suggest that foliar Zn application is a promising way to improve the grain Zn concentration and decrease the phytate : Zn molar ratio, thus being beneficial for human diets, but the effects of rice variety, cropping season, and the polishing process should be considered.

Comparative Effects of Calcium, Boron, and Zinc Inhibiting Physiological Disorders, Improving Yield and Quality of Solanum lycopersicum.

Localized calcium deficiency at the tomato flower end causes a physiological disorder called blossom end rot, resulting in yield losses of up to 50 percent. Fruit cracking is another physiological disorder of tomatoes that most often occurs when the movement of water and solutes to the tomato is protracted or rapid, but the underlying cause of fruit cracking is, again, calcium deficiency. Therefore, the present field experiment was conducted with the aim of increasing yield and reducing physiological disorders in tomatoes with a foliar application of calcium and micronutrients (zinc and boron). Four levels of calcium (0, 0.3, 0.6, and 0.9%), three levels of boron (0, 0.25, and 0.5%), and three levels of Zinc (0, 0.25, and 0.5%) were applied foliarly three times (starting at flowering, the 2nd application was repeated when the fruits set, and the 3rd after a period of 15 days from the fruits set). An addition of 0.6% calcium increased yield and associated traits with a decreased flower drop. Likewise, a 0.9% calcium addition increased fruit Ca content and decreased blossom end rot, fruit cracking, and Zn content. Foliar spraying with 0.25% boron (compound B) improved flowering and production while reducing flower drop and tomato fruit cracking. Similarly, an application of 0.5% B significantly increased Ca and B content with minimal blossom end rot and Zn content. Likewise, a 0.5% Zn application resulted in yield and yield-related traits with increased fruit B and Zn contents while blossom end rot, fruit cracking, and fruit Ca content were lower when 0.5% of foliar Zn was applied. Therefore, it is concluded that a foliar application of Ca, B, and Zn can be used alone or in combination to minimize the physiological disorders, increase production, and improve tomato fruit quality.

Organic Zn and nano-Zn amino acids chelates modulate quality growth attributes and antioxidants activity for biofortified apple (Malus x domestica Borkh.) production

Zinc biofortification increase nutritional content of crops to combat Zn deficiency in human diets. Foliar Zn bio-organics can significantly improve Zn content of fruit crops. This method is efficient, can be tailored to specific crop needs, and is crucial for enhancing the nutritional quality of food crops, contributing to better human health outcomes. In order to evaluate the efficacy of foliar sprays in promoting plant growth and development, the study evaluated the comparative efficacy of zinc amino acid complexes with zinc sulphate in apple (Malus × domestica Borkh.) cv. Gala Schniga Schnico during the years 2022 and 2023. Different Zn nutrient sources namely, Zn glycinate (Zn-Gly), Zn gluconate (Zn-Glu), Zn amino acid chelate (Zn-AAC), nano Zn amino acid chelate (NZn-AAC) were applied at the rate of 200 and 400 mg/L each and conventional ZnSO4 at 1250 mg/L with three replicates. Foliar application of the Zn nutrient sources was executed at four stages i.e., 15 days before petal fall, petal fall, 15 days after petal fall, and after harvest. The results revealed that NZn-AAC at 400 mg kg-1 registered the maximum increase in vegetative growth and flowering traits. The superior treatment also exhibited highest fruit set (62.90 %) and fruit yield (5.62 kg/tree) in apple. Fruit quality parameters, in terms of TSS, total sugars, ascorbic acid and anthocyanin contents were increased by 22.9, 17.8, 50.2, and 16.6 per cent, respectively through superior treatment. Fruit flesh and peel nutrient content in terms of P, K, Ca, Mg and Zn also showed improvement through NZn-AAC400 compared to control. Maximum decrease in phytic acid (1.09 %) and increase in ursolic acid (273.95 µg/mL) were also reported with NZn-AAC400. The differences between Zn nutrient sources were analysed using PCA, which explained 95.70 per cent (PC1), 97.81 per cent (PC2), 99.11 per cent (PC3), 99.42 per cent (PC4) and 99.63 per cent (PC5) of the cumulative variance based on Eigen value (>1). In accordance with the results, Zn amino acid complexes emerged as beneficial environment-friendly Zn source for improving growth, fruit yield, quality with higher Zn bio-availability compared to ZnSO4.

Influence of Foliar Zinc Application on Cadmium and Zinc Bioaccessibility in Brassica chinensis L.: In Vitro Digestion and Chemical Sequential Extraction.

Foliar zinc (Zn) application can affect the accumulation and bioaccessibility of cadmium (Cd) and Zn in crops. However, the mechanisms by which foliar Zn application influences Cd and Zn bioaccessibility remain elusive. This study examined the effects of spraying ZnSO4 and ZnNa2EDTA on bioaccessibility and chemical forms of Cd and Zn in pakchoi (Brassica chinensis L.) shoots and evaluated human health risks via pakchoi consumption. Spraying ZnSO4 reduced the concentrations of ethanol-extractable (Fethanol) and deionized water-extractable (Fd-H2O) Cd, as well as the corresponding bioaccessible Cd concentrations (20.3-66.4%) and attendant health risks of Cd, whereas spraying high-dose ZnNa2EDTA significantly increased the concentrations of both Cd forms and bioaccessible Cd. Spraying ZnSO4 and high-dose ZnNa2EDTA significantly increased the concentrations of Zn in Fethanol and Fd-H2O and the corresponding bioaccessible Zn concentrations (0.8-8.3-fold). Fethanol and Fd-H2O were the primary sources of bioaccessible Cd and Zn, contributing more than 59% of the bioaccessible Cd and Zn. These results indicate that foliar Zn application can affect Cd and Zn bioaccessibility in pakchoi mainly by modulating Cd and Zn in Fethanol and Fd-H2O. These findings provide scientific support for the development of more efficient measures to produce safe and high-quality leafy vegetables from Cd-polluted soils.

Zinc foliar application may alleviate drought stress in wheat species through physiological changes

Drought is the greatest threat to food security in the climate change scenario, which affects crop plants' growth and development by disturbing the plant's physiological and biochemical processes. Zinc (Zn) is an essential micronutrient in many metabolic processes and may improve plant tolerance to water deficit conditions besides its nutritional value.This study investigated the reaction of several wheat species with different ploidy levels to foliar Zn application under water stress. Water stress significantly reduced grain yield (GY), leaf relative water contents (RWC), chlorophyll (Chla and Chlb), and carotenoid (Car) contents. Water stress also impacted several other physiological characteristics by increasing leaf hydrogen peroxide (HP), free proline (Prl), malondialdehyde (MDA) contents, soluble protein (PC), sodium content (Na+), and antioxidant enzymes, including peroxidase (Pox), ascorbate peroxidase (Aes) and catalase (Cat). Remarkably, the Zn application alleviated yield reduction caused by water stress. Moreover, the Zn application increased grains' Zn, potassium content (K+), and K+/Na+ ratio, RWC, Chl, Car contents, Pox, Aes, and Cat activities while significantly reducing MDA, HP, and Na+ contents compared with the control treatment. Pox, Aes, and Cat activities increased to higher concentrations in 6x and 4x than in 2x, indicating that the 6x and 4x species responded better to water stress. Wild and landrace varieties of 4x, such as T. dicoccum, T. ispahanicum, and T. dicoccoides, showed better water stress tolerance than the landrace varieties of 2x and 6x species. These species may be a valuable genetic source for improving modern bread and durum wheat to water stress.

Soil and Foliar Zinc Biofortification of Triticale (x Triticosecale) under Mediterranean Conditions: Effects on Forage Yield and Quality.

Zinc (Zn) deficiency represents a significant global concern, affecting both plant and human health, particularly in regions with Zn-depleted soils. Agronomic biofortification strategies, such as the application of Zn fertilizers, offer a cost-effective approach to increase Zn levels in crops. This study aimed to assess the efficacy of soil and foliar Zn biofortification, applied as an aqueous solution of 0.5% zinc sulphate (ZnSO4·7H2O), on triticale (x Triticosecale) grown under Mediterranean conditions. The study was conducted over two growing seasons (2017/18 and 2018/19) in southern Spain, evaluating the effects on biomass yield; forage quality, including crude protein, Van Soest detergent fiber, organic matter digestibility, and relative forage value; and nutrient accumulation. Soil treatment consisted in the application of 50 kg of ZnSO4·7H2O ha-1 solely at the beginning of the first campaign to assess the residual effect on the second year. In contrast, the foliar treatment consisted of two applications of 4 kg of ZnSO4·7H2O ha-1 per campaign, one at the beginning of tillering and the other at the appearance of the first node. The foliar application increased the Zn content of the forage to adequate levels, while the soil application resulted in a 33% increase in biomass production, which is particularly beneficial for farmers. Overall quality was favored by the combined soil + foliar application, and no adverse antagonistic effects on other nutrients were detected. Instead, a synergistic interaction between Se and Zn was observed, which improved the efficacy of this important micronutrient for livestock and human wellbeing.

Optimizing Grain Zinc Biofortification in Bread Wheat: Innovative Fertilization Strategies for Field Conditions

Zinc deficiency in humans is of worldwide concern. The aim of this study is to enrich grains with Zn through soil application at different doses and foliar application from various sources. For this purpose, two independent field experiments have been conducted. In Experiment I, Zn (ZnSO4.7H2O) was applied through soil as basal and top dressing. The treatments were Zn0: control, Zn1: 5 kg Zn ha−1 as basal, Zn2: 2.5 kg Zn ha−1 as basal and 2.5 kg Zn ha−1 as top dressing and Zn3: 5 kg Zn ha−1 as top dressing. In Experiment II, Zn was applied as foliar from different sources (ZnSO4.7H2O, Zn-Methionine, Zn-Polyol and Zn-EDTA) at different growth stages with or without urea. In both experiments, Zn concentration in the grain and leaves of wheat and grain yield increased while phytic acid and PA/Zn molar ratio decreased due to soil or foliar Zn application. It was determined that the application of ZnSO4.7H2O in the soil at the top dressing period in Experiment I and the application of ZnSO4.7H2O and Zn-Methionine forms together with urea in Experiment II were effective methods in increasing grain yield and grain Zn concentration. The application of ZnSO4.7H2O from both soil and foliar sources, especially in combination with urea, has proven to be highly effective in the Zn biofortification of wheat grains. It is possible to assert that the use of ZnSO4.7H2O, which is cost-effective compared to other sources, could contribute significantly to enhancing zinc nutrition in humans.

Combining Zinc Biofortification and Native Trichoderma Inoculation Strategies for Subterranean Clover

Using beneficial microorganisms along with sustainable strategies such as agronomic biofortification offers eco-friendly alternatives to combat climate change in ecosystems like dehesas. This study analyzes the combined effects of four wild Trichoderma spp. isolated from Extremadura, Spain (T. koningiopsis, two T. gamsii, and T. koningii, with negative and positive controls) and four Zn biofortification treatments (no Zn application; soil application of 5 mg of ZnSO4·7H2O per kg of soil, labeled soil Zn; two foliar applications of 5 mL 0.5% ZnSO4·7H2O, labeled foliar Zn; and soil + foliar combination, labeled SF) on Trifolium subterraneum performance. The combination of T. koningiopsis and T. gamsii with foliar Zn improved plant growth by up to 34.4%. Zinc accumulation was about 30% higher when T. gamsii and T. koningii were applied with SF, and their inoculation resulted in a 2.5-fold increase in ash. Trichoderma spp. affected nodulation differently; both T. gamsii inhibited nodulation by 24%, whereas neither T. koningiopsis nor T. koningii showed differences from the controls. These results highlight the potential of combining beneficial microorganisms with biofortification strategies to address nutrient deficiencies and improve agricultural sustainability. However, the complex interactions between both factors underscore the importance of strain selection and call for further research to optimize application strategies and elucidate underlying mechanisms.

Foliar-applied zinc promotes cadmium allocation from leaf surfaces to grains in rice

The accumulation of Cd by rice poses significant health risks. Foliar fertilization with Zn can reduce grain Cd contents in rice grown in Cd-contaminated soils. However, atmospheric deposition on leaves is another vector of Cd contamination, and it remains unclear how Zn application affects the allocation of such Cd. We conducted an experiment where the flag leaves of rice plants were treated with solutions with various Zn concentrations and a constant Cd concentration. The 111Cd stable isotope was used to trace the flux of foliar-applied Cd. Higher levels of foliar-applied Zn enhanced Cd efflux and grain allocation. This is attributed to limited sequestration of foliar-applied Cd in the leaf cell symplasm and increased Cd desorption from leaf cell walls when a high Zn2+ concentration occurs in the apoplast. Nonionic Zn oxide nanoparticles mitigated these effects. Additionally, the expressions of OsLCT1 and OsZIP7 in flag leaves and OsHMA2 and OsZIP7 in the uppermost nodes were upregulated under high-Zn2+ treatment, which may facilitate Cd phloem loading and grain allocation. Caution is advised in using foliar Zn in areas with high atmospheric Cd due to potential grain-contamination risks.

The effects of foliar amino acid and Zn applications on agronomic traits and Zn biofortification in soybean (Glycine max L.).

The production and consumption of soybeans are widespread due to their nutritional and industrial value. Nutrient enrichment is vital for improving the nutritional quality of soybeans. This study aimed to evaluate the effect of foliar application of amino acids (AA) and zinc (Zn) on agronomic traits and the accumulation of grain Zn in soybeans. The experimental design comprised 16 treatment combinations involving four levels of amino acid application (0, 50, 100, and 150 ml 100 L-1) and Zn (0, 2, 4, and 6 mg L-1) following a randomized complete block design with three replications in field conditions. The results demonstrated that the application of foliar Zn and AA did not affect the yield, whereas that of AA50*Zn2 and AA150*Zn2 affected the number of pods and branches. The effects of AA application on N and the protein content in grains were determined to be significant. The application of AA100*Zn6 emerged as the most effective treatment for the enhancement of Zn biofortification in soybean grains. The combined foliar application of AA and Zn contributed to enhanced Zn accumulation in the grains.

Role of Nutrient Management in Yield, Quality and Nutrient Content of Egyptian Clover (Trifolium alexandrinum L.) Under Calcareous Soil Conditions

Nutrient management is vital for maximizing forage crop yield and economic viability; however, improper application can result in decreased yield and quality. Therefore, two seasonal experiments were conducted during the winter seasons of 2022-2023 and 2023-2024 to examine the impact of varying nitrogen, phosphorus and potassium (NPK) levels, along with the foliar application of zinc, on the forage yield and nutrient content of Egyptian clover or berseem (Trifolium alexandrinum L.) grown in calcareous soil conditions (>36% CaCO3). The experiment consisted of eight treatments, including two NPK levels (50% and 100% of the recommended dose) and two forms of Zn (Zn NPs and Zn Edta at 0.2 and 0.5% as foliar sprays), compared with the control (without treatment). Results showed that NPK full dose (100%) or in combination with Zn NPs significantly improved fresh and dry weight by an average of 67%, and 80%, respectively, across all cuts. Whereas, the highest protein percentage in berseem forage occurred with 50% NPK and foliar Zn NPs. Protein yield per unit area was highest with 100% NPK and foliar Zn NPs in the second and third cuts. Furthermore, Zn NPs boosted manganese (Mn) levels in the 2nd cut but decreased them in the 3rd cut. Iron (Fe) and Mn were mostly in normal ranges, but zinc was often below normal levels. Overall, Zn NPs increased forage yields. The results of translocation factor (TF) for micronutrients from the soil to berseem plants showed that TF values were > 1 for all micronutrients except for Cu in several instances in the 2nd cut in such calcareous soil. Furthermore, micronutrient translocations were arranged in the following order Cu < Zn <Mn <Fe in the 2nd and 3rd cuts. Our study suggested that there is a beneficial role of correcting Zn deficiency under calcareous soil conditions which is reflected on berseem yield and quality and nutrient status. Thus, using ZnO NPs along with the full recommended dose of NPK is a suitable approach to enhance berseem crop yield and quality in calcareous soil.

Improving the Productivity and Nutritional Values of Sweet Potato (Ipomoea batatas L.) with a Combination of Soil and Foliar Zinc

Sweet potato (Ipomoea batatas L.) is an important crop and is a staple food in many countries across the globe; since they are a good source of nutrients including zinc (Zn). Zn is essential for plant growth and development, and a zinc deficiency can significantly impact crop productivity as well as the nutritional quality of the produce. The value of enrichment with Zn in many crops by applying Zn either to foliar or soil through agronomic biofortification has been investigated, but this information is still unavailable for sweet potatoes. Therefore, the current study aimed to evaluate the effect of soil and foliar Zn applications on yield, biochemical traits, and nutrient concentrations of different sweet potato genotypes. The study was conducted using a split-plot design with treatments of two doses (0 and 2.5 kg Zn ha-1) of soil application and four doses (0, 15, 30, and 45 ppm) of foliar application of Zn on five sweet potato genotypes (SP-2, SP-14, SP-15, SP-16, SP-20). It was observed that growth and yield performance as well as nutrient concentrations in the tubers of sweet potatoes were greatly influenced by Zn application method and genotype. An increasing rate of foliar Zn, with or without soil-applied Zn, showed an increasing trend in amino acid, β-carotene, flavonoid, and phenolic content. The foliar Zn application had a more obvious effect on most of the examined traits than the soil Zn application and except for a few characteristics (dry matter and amino acids), most traits responded up to the foliar application of 15 ppm Zn, and thereafter no increase was seen with further increments of foliar Zn application.

Cadmium (Cd) Minimization and Zinc (Zn) Biofortification in Wheat (Triticum aestivum L.) Grains by Spraying with the Foliar Zn Fertilizer in Cd-Contaminated Fields

The foliar application of zinc (Zn) has been regarded as a practical and economical way to reduce grain cadmium (Cd) accumulation and enhance grain quality in crops. Herein, a two-year field experiment was carried out to examine the efficacy of different application rates of the foliar Zn fertilizer in Cd reduction and microelement biofortification in wheat (Triticum aestivum L.) grains. The results show that the T4 and T5 treatments, 500 and 250-fold dilution of the foliar Zn fertilizer, respectively, increased the grain yield to varying degrees in the two years. When compared with controls and based on the average of the two years’ results, spraying with the foliar Zn fertilizer remarkably decreased grain Cd concentrations (44.5%), Cd translocation from stem to grain (TFStem/Grain) (4.92%), the HRI values of Cd (45.5%), PA/Ca (27.8%), PA/Fe (21.4%) and PA/Mn (5.81%) under the T2 treatment (1000-fold dilution). Furthermore, the T2 treatment significantly increased the Zn (37.8%), Ca (48.9%), Fe (37.6%), Mn (14.8%) and total protein (7.92%) contents and the estimated Zn bioavailability (28.9%) in wheat grains after two years. All these findings suggest that the foliar Zn fertilizer holds considerable promise as a safe crop production technique and a means of mitigating “hidden hunger” in developing countries.

Soil and foliar zinc application techniques influence the productivity, zinc concentration, and protein content in the grains of bread wheat varieties

Micronutrient zinc (Zn) is crucial for both humans and plants. To improve the micronutrient concentration in the grains of food crops, biofortification has already been established as one of the best approaches across the globe. The current study was carried out to assess Zn enrichment in a few common wheat varieties using different Zn delivery techniques. The following treatments were applied: T<sub>1</sub>: control (without Zn), T<sub>2</sub>: Soil application of 4 kg Zn ha-1 at final land preparation, T<sub>3</sub>: Foliar application of a 0.5% Zn solution (ZnSO<sub>4</sub> x7H<sub>2</sub>O) at both tillering and booting stages, and T<sub>4</sub>: soil application of 2 kg Zn ha-1 at final land preparation + foliar application of a 0.2% Zn solution (ZnSO<sub>4</sub> x7H<sub>2</sub>O) at both tillering and booting stages. All treatments were arranged in a split-plot design and repeated three times The findings of the study revealed that the various Zn application techniques had an impact on the Zn concentration in grains significantly, ranging from 23.9 to 32.2 µg g-1 across the varieties, with an average of 28.2 µg g-1 in the control. Among these various application techniques, the soil + foliar application induced the highest response of the Zn concentration in the grains ranging from 33.7 to 37.60 µg g-1. The average protein content (%) in the grains of all wheat varieties varied by 1.21, 1.47, and 1.51%, respectively, as a result of the use of the different Zn application methods. Considering the Zn-use efficiency (%), the most Zn-efficient wheat variety was BARI Gom 28, followed by BARI Gom 26, Binagom-1, BARI Gom 25, and BARI Gom 29. In the case of grain yield, wheat variety BARI Gom 26 (4.15 t ha-1) performed the best in the soil + foliar Zn application. The soil + foliar application method outperformed the other application techniques regarding the Zn concentration, yield, and protein content in the grain.

The Influence of the Levels and Addition Methods of Zinc on Stimulating some Enzymes to Resist Salinity

A field experiment was conducted in Haditha city – Anbar governorate in winter season of 2021-2022, in a loamy texture soil to study the influence of levels and addition methods of Zinc to stimulate some enzymes for increasing the tolerance of wheat crop to salinity. The experiment was designed with randomized complete blocky design with split plots (R. C. B. D), by three replicates included included the experiment included soaking the seeds before planting with zinc in three levels of zinc, the first level (0) which represents the comparison treatment (soaking with water only) and the second level (75) which represents the soaking of the seeds with zinc at a concentration (75 mg Zn kg−1) while the third level included the soaking of the seeds with zinc With a concentration of (150 mg Zn kg−1) for eight hours, then the plant was sprayed with the same concentrations above in two batches, the first at the branching stage and the second was at the plant booting stage.The statistical analysis results showed that Zn addition (seed soaking and foliar spraying), led to reduction of harmful effects of saline stress, as well as increasing Zn concentration in soil, wheat straw, roots, 1000 grain weight m, grains yield and activity of antioxidants enzymes (POD and CAT). The best results have achieved by using the level 150 mg kg−1 Zn with seed soaking and with foliar Zn spraying on plant together and that reduce the effects of saline stress in plant.

The potential of biofortification technologies for wheat and rice to fill the nutritional Zn intake gap in China.

Zinc (Zn) deficiency in humans is of worldwide concern. The objective of this study was to investigate the Zn intake gap in Chinese adults and identify the potential role of biofortification technologies for wheat and rice, including crop nutrient management and breeding, in filling the gap. We use data from the China Health and Nutrition Survey in 2011 to identify food consumption patterns and dietary Zn intake of 4512 adults to define and quantify the Zn intake gap in the population. The dietary Zn intake gap of surveyed adults ranged from -0.8 to 6.53 mg day-1 across nine provinces and differences were associated with differences in food consumption patterns. Both dietary Zn intake and Zn gap for males were higher than for females. The potential of changes in five management strategies (improved nitrogen fertilization, improved phosphorus fertilization, foliar Zn fertilization, improved water management and growing varieties reaching the grain Zn breeding target) was analyzed. Breeding and foliar Zn fertilization were shown to be the two most effective management strategies that could increase dietary intake by 1.29 to 5 mg Zn day-1 dependent on sex and province. This study shows that the Zn gap varied across regions in China, with some large enough to warrant interventions. Wheat and rice as two major Zn sources could be targeted without a direct need for dietary diversification. By promoting both biofortification breeding of wheat and rice and Zn fertilization, dietary Zn intake could be enhanced to contribute to human health improvement in China. © 2023 Society of Chemical Industry.

Enhancing wheat production and quality in alkaline soil: a study on the effectiveness of foliar and soil applied zinc

Cultivation of high-yield varieties and unbalanced fertilization have induced micronutrient deficiency in soils worldwide. Zinc (Zn) is an essential nutrient for plant growth and its deficiency is most common in alkaline and calcareous soils. Therefore, this study aimed to evaluate the effect of Zn applied either alone or in combination with foliar application on the quality and production of wheat grown in alkaline soils. Zn was applied in the form of zinc sulfate (ZnSo4) to the soil and as a foliar spray during the sowing and tillering stages, respectively. Results showed that Zn fertilization of wheat, irrespective of modes of application, significantly increased grain and biological yield, grain per spike, and 1,000 grains weight over control; however, its effect was more noticeable when applied as 7.5 kg ha−1of soil Zn combined with foliar Zn at 2.5 kg ha−1. Zn application significantly increased the grain protein content from 9.40% in the control to a maximum of 11.83% at soil Zn of 10 kg ha−1. Similarly, Zn application improved Zn, phosphorus (P), and potassium (K) concentrations in wheat grains. Moreover, correlation analysis showed that the grain Zn concentration was positively correlated with the grain P concentration. The correlation between P concentration in wheat grains and 1,000 grain weight was not significant. A total of 1,000 grains weight was positively correlated with tillers per plant, grain yield, and biological yield. There were positive correlations between protein content, biological yield, grain yield, and tillers per plant. Therefore, soil-applied Zn + foliar application in alkaline soils with limited Zn availability is crucial for improving wheat yield and grain quality.

Role of Temporal Zn Fertilization along with Zn Solubilizing Bacteria in Enhancing Zinc Content, Uptake, and Zinc Use Efficiency in Wheat Genotypes and Its Implications for Agronomic Biofortification

Wheat (Triticum aestivum L.) is a vital cereal crop for food security in Pakistan. In Zn-deficient soils, its productivity and quality suffer, affecting grain yield, Zn bioavailability, and nutrition, which can lead to malnutrition. Field experiments were conducted using factorial randomized block design at the Agricultural Research Institute (ARI) Tarnab, Peshawar, Pakistan to evaluate the impact of wheat genotypes (G1-TRB-72-311 synthetic hexaploid, G2-TRB-89-348 advanced line, and G3-Pirsabak-19-approved variety), Zn application methods (AM1: no Zn application, AM2: seed priming with 0.5% Zn, AM3: soil application of 10 kg ha−1 Zn, and AM4: foliar application of 0.5% Zn), and the experiment also explored the use of ZSB (BF1: with bacteria, BF0: without bacteria) to cope with Zn deficiency. The study revealed significant impacts on wheat’s Zn content, uptake, and nutrient efficiency, arising from genotypes variance, Zn application approaches, and ZSB. TRB-72-311 synthetic hexaploid genotype with 0.5% foliar Zn and ZSB excelled, enhancing grain (17.8%) and straw Zn (23.1%), increasing total Zn uptake (55.0%), reducing grain phytic acid (11.7%), and boosting Zn-related efficiencies in wheat. These results prompt further discussion regarding the potential implications for agricultural practices. In conclusion, utilizing the TRB-72-311 genotype with 0.5% foliar Zn application and ZSB enhances wheat’s Zn content, uptake, grain quality, and addresses malnutrition.

Alleviation of cadmium toxicity and fortification of zinc in wheat cultivars cultivated in Cd contaminated soil

To address food production challenges and combat heavy metal toxicity, an economically viable and sustainable approach is essential. Cadmium (Cd) contamination poses risks to crops and human health. Leveraging the structural similarity between zinc (Zn) and cadmium, we explored foliar Zn spray's potential to alleviate Cd toxicity and enhance wheat yield. Our field study near Peshawar, Pakistan, during the 2021–2022 winter, employed a split-plot design to investigate Zn's impact on wheat biofortification. Across three wheat varieties (JANBAZ-10, Pirsabak (PS)-2013, PS-2015), four foliar Zn levels (0 %, 0.5 %, 1.0 %, 1.5 % solution) were tested at various growth stages. Pirsabak-2015 exhibited optimal results, with a 1 % foliar Zn treatment producing the highest grain yield (3409 kg ha−1), biological yield (9022 kg ha−1), grains per spike (56), and 1000-grain weight (40.6 g). Application of 1 % biochar also significantly increased grain yield. Zn concentration peaked in grains and leaves with 1.5 % Zn solution, followed by 1.0 % Zn in the PS-2015 cultivar. Moreover, 1 % Zn application enhanced photosynthetic parameters and significantly reduced cadmium concentrations in leaves and grains. Notably, 1.0 % Zn led to improved stress tolerance as indicated by decreased electrolyte leakage and increased superoxide dismutase and peroxidase activities. Applying 1.0 % Zn solution as a foliar spray during different growth stages demonstrates the potential to enhance wheat yield, increase grain Zn content, and mitigate Cd toxicity in Cd-contaminated soil. Further research across diverse cereal crops and climates will help establish 1.0 % Zn foliar spray as an effective Cd stress mitigation strategy.