Foliar Zn Fertilization Research Articles

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.

Effect of Biofortified and Non-Biofortified Varieties and Zinc Fertilization Strategies on Growth, Productivity and Profitability of Rice

The field experiment was conducted in the rainy (Kharif, June to October) seasons of 2019 and 2020 at ICAR-Indian Agricultural Research Institute, New Delhi, India with the objective to appraise the effect of biofortified and non-biofortified varieties and zinc fertilization strategies on the growth, productivity and profitability of rice. The biofortified variety DRR Dhan 45 recorded a higher value of dry matter accumulation, leaf area index, and crop growth rate, and the non-biofortified variety Pusa 44 recorded higher effective tillers, panicle weight, filled grain weight per panicle, number of filled grains and total grains per panicle, fertility percentage and grain yield (5.2 t ha-1), though the performance of both varieties was statistically similar. But, the higher straw yield was recorded with the non-biofortified variety, Pusa Basmati 1121 (10.8 t ha-1). Pusa Basmati 1509 recorded higher cost of cultivation, gross returns, net returns and B:C. Among zinc fertilization strategies, soil application of 2.5 kg Zn ha-1 along with the foliar application of 0.5% ZnSO4.7H2O at maximum tillering and anthesis stages recorded higher growth parameters, yield, and yield attributes and better economics. On average, the soil+foliar Zn application increased grain yield by 14% and straw yield by 10.5%, and gross returns and net returns by 15.6% and 26.7%, respectively, than the control. Cultivation of rice varieties, Pusa 44 or DRR Dhan 45, along with soil+foliar Zn fertilization enhanced growth and productivity, while the aromatic variety, Pusa Basmati 1509 enhanced the profitability.

Determining the Effect of Zinc Fortification on Growth, Yield and Economics of Wheat (Triticum aestivum L.) Under Irrigated Condition

The present study propose to explore the possibility of agronomic biofortification for enhancing the Zn content of wheat through ferti-fortification of wheat crops with Zn at appropriate dose and time during its growth. The productivity and nutritional value of wheat, as well as human health, are seriously hampered by zinc (Zn) deficiency in soil. A popular technological remedy for the issue is Zn fertilisation to increase its uptake in grains. Accordingly, the present field study was undertaken to assess the impacts of different Zn fertilization on growth, yield and economics returns of wheat at Regional Research Sub Center NARP, Saini, Kaushambi, UP during Rabi season of 2020-21. Five Zn treatments (control, 5 kg zinc/ha, 7 kg zinc/ha, 10 kg zinc/ha and 5 kg zinc/ha+2 two foliar spray @5%of Zn So4 at tillering and before flowering) were taken in randomized complete block design with three replication. Results showed that relative effectiveness of different Zn fertilization was varied for the crop attributes studied. Soil + foliar fertilization was superior in increasing grain yield (9.88% over the control). Moreover, for an optimum balance among all the tested attributes including Plant height, crop dry weight, yield attributes, yield, HI and returns and Zn content in grain were significantly higher under soil fertilization combined with foliar Zn fertilization (T5) over other treatments. The findings of this study can serve as guidelines for high-quality, sustainable wheat production, which will aid in the fight against malnutrition.

Optimizing zinc fertilization technology in wheat for its sustainable production and improved human nutrition

ABSTRACT Zinc (Zn) deficiency in soil is a serious constraint affecting the yield and nutritional quality of wheat and, in turn, human health. Zn fertilization for enhancing its density in grains is a prominent technological solution for the problem. Accordingly, the present study (pot experiment) was undertaken to (i) assess the impacts of different Zn fertilization technologies on yield, concentrations of Zn, phytic acid (PA), iron (Fe) and also the bioavailability of Zn in grains and (ii) determine the optimised Zn fertilization technology that balances all the above attributes. To achieve this, six Zn fertilization technologies, namely, soil fertilization alone, combined soil and foliar fertilization at maximum tillering, jointing, flowering, dough stages and also foliar fertilization alone were tested and compared with control (no Zn) in forty different soil series representing two distinct soil orders, Inceptisols and Alfisols. Results showed that relative effectiveness of different Zn fertilization technologies varied for the crop attributes studied. Soil + foliar fertilization was superior in increasing grain yield (10–13% over the control). Moreover, for an optimum balance among all the tested attributes including bioavailability of Zn to human, foliar Zn fertilization at later crop growth stage (i.e. dough) combined with soil fertilization was the best. It was found that biofortified wheat grains obtained through Zn fertilization, on an average, could supply about 1.5 times more bioavailable Zn than the normal grains. Therefore, the outcomes of this study can provide a guideline for sustainable and quality wheat production, which will help address the malnutrition challenge.

Translocation of Foliar Absorbed Zn in Sunflower (Helianthus annuus) Leaves.

Foliar zinc (Zn) fertilization is an important approach for overcoming crop Zn deficiency, yet little is known regarding the subsequent translocation of this foliar-applied Zn. Using synchrotron-based X-ray fluorescence microscopy (XFM) and transcriptome analysis, the present study examined the translocation of foliar absorbed Zn in sunflower (Helianthus annuus) leaves. Although bulk analyses showed that there had been minimal translocation of the absorbed Zn out of the leaf within 7 days, in situ analyses showed that the distribution of Zn in the leaf had changed with time. Specifically, when Zn was applied to the leaf for 0.5 h and then removed, Zn primarily accumulated within the upper and lower epidermal layers (when examined after 3 h), but when examined after 24 h, the Zn had moved to the vascular tissues. Transcriptome analyses identified a range of genes involved in stress response, cell wall reinforcement, and binding that were initially upregulated following foliar Zn application, whereas they were downregulated after 24 h. These observations suggest that foliar Zn application caused rapid stress to the leaf, with the initial Zn accumulation in the epidermis as a detoxification strategy, but once this stress decreased, Zn was then moved to the vascular tissues. Overall, this study has shown that despite foliar Zn application causing rapid stress to the leaf and that most of the Zn stayed within the leaf over 7 days, the distribution of Zn in the leaf had changed, with Zn mostly located in the vascular tissues 24 h after the Zn had been applied. Not only do the data presented herein provide new insight for improving the efficiency of foliar Zn fertilizers, but our approach of combining XFM with a transcriptome methodological system provides a novel approach for the study of element translocation in plants.

The effectiveness of foliar applications of different zinc source and urea to increase grain zinc of wheat grown under reduced soil nitrogen supply

Nitrogen is important for the enrichment of grain Zn when Zn is foliarly applied. However, decreasing soil N input has become a major issue for environmental protection. A 2-yr field experiment was conducted to evaluate the effectiveness of spraying different Zn sources [ZnSO4 or Zn(Gly)2] combined with or without urea on grain Zn concentration and bioavailability under reduced soil N rates, both in single wheat plantation and winter wheat-summer maize rotation. Results showed that foliar application of Zn(Gly)2 significantly increased grain Zn concentration by 88% under wheat-summer maize rotation and 150% under single wheat plantation. The effectiveness of foliar ZnSO4 application in increasing grain Zn was similar with that of Zn(Gly)2. Adding urea to foliar ZnSO4 or Zn(Gly)2 further increased grain Zn concentration under reduced soil N rates. Grain Zn biavailability increased with the reduction of soil N rates, but decreased after application of foliar Zn fertilizers. Foliar fertilization significantly increased protein, Fe, and Mn concentrations in grain, and the magnitudes of these increases were greater when Zn(Gly) 2 alone or ZnSO 4 plus urea were applied. Simultaneous foliar application of ZnSO4 and urea slightly increased farmer’s net income. These results suggest that foliar application of ZnSO 4 plus urea can be used as efficient and economical fertilization strategies to increase Zn concentration and bioavailability in wheat grain under reduced soil N supply, and consequently minimize Zn deficiency in humans.

Site-Specific Factors Influence the Field Performance of a Zn-Biofortified Wheat Variety

© Copyright © 2020 Zia, Ahmed, Bailey, Lark, Young, Lowe, Joy, Wilson, Zaman and Broadley. Background: Biofortification of wheat with zinc (Zn) through breeding and agronomy can reduce Zn deficiencies and improve human health. “High-Zn” wheat varieties have been released in India and Pakistan, where wheat is consumed widely as a dietary staple. The aim of this study was to quantify the potential contribution of a “high-Zn” wheat variety (Triticum aestivum L. var. Zincol-2016) and Zn fertilizers to improving dietary Zn supply under field conditions in Pakistan. Methods: Grain Zn concentration of Zincol-2016 and local reference varieties were determined at three sites of contrasting soil Zn status: Faisalabad (Punjab Province; diethylenetriamine pentaacetate- (DTPA-)extractable Zn, 1.31 mg kg−1 soil; gross plot size 13.3 m2; n = 4; reference var. Faisalabad-2008), Islamabad (Capital Territory; 0.48 mg kg−1; 4.6 m2; n = 5; reference var. NARC-2011), and Pir Sabak (Khyber Pakhtunkhwa, KPK, Province; 0.12 mg kg−1 soil; 9.1 m2; n = 4; reference vars. Pirsabak-2015, Wadhan-2017). Eight Zn fertilizer treatment levels were tested using a randomized complete block design: control; soil (5 or 10 kg ha−1 ZnSO4.H2O; 33% Zn applied at sowing); foliar (0.79 or 1.58 kg of ZnSO4.H2O ha−1 applied as a 250 L ha−1 drench at crop booting stage); three soil × foliar combinations. Results: At the Faisalabad site, the grain Zn concentration of Zincol-2016 was greater than Faisalabad-2008, with no yield penalty. Zincol-2016 did not have larger grain Zn concentrations than reference varieties used at Islamabad or Pir Sabak sites, which both had a lower soil Zn status than the Faisalabad site. Foliar Zn fertilization increased grain Zn concentration of all varieties at all sites. There were no significant effects of soil Zn fertilizers, or variety·fertilizer interactions, on grain Zn concentration or yield. Conclusions: Environment and management affect the performance of “high-Zn” wheat varieties, and these factors needs to be evaluated at scale to assess the potential nutritional impact of Zn biofortified crops. Designing studies to detect realistic effect sizes for new varieties and crop management strategies is therefore an important consideration. The current study indicated that nine replicate plots would be needed to achieve 80% power to detect a 25% increase in grain Zn concentration.

Impacts of combined N and Zn application on Zn translocation, partitioning, and accumulation in Triticum aestivum

Field experiment was conducted to examine the effects of combined application of N and Zn fertilizers on translocation, distribution, and accumulation of Zn in different organs in wheat plants. The results showed that Zn concentration and Zn accumulation in each organ were significantly different under different treatments. Compared with N3 (120 kg·hm-2), the grain Zn concentration of N1 (240 kg·hm-2) and N2 (180 kg·hm-2) increased 22.0% and 8.9%, respectively. Compared with the non-Zn application treatment (CK), grain Zn concentration under ZnS (soil Zn fertilization), ZnF (foliar Zn fertilization), and ZnS+ZnF (soil Zn fertilization combined with foliar Zn fertilization) treatments were increased by 5.4%, 60.5% and 72.8%, while Zn accumulation in grain were increased by 21.3% 82.5% and 102.4%, respectively. Zn in grain mainly came from the remobilization of Zn uptaken after antheis, with the accumulative contribution being 89.9% and 100.0% in ZnF and ZnS+ZnF, respectively. Compared with ZnS, Zn fertilizer recovery and use efficiency of ZnF and ZnS+ZnF were increased by 4.8, 1.1 times and 7.9, 2.2 times, respectively. Under current condition, Zn concentration and Zn accumulation in different organs of wheat increased with increasing N rate when it was less than 240 kg·hm-2, which was significantly increased in the grain by foliar Zn application. Therefore, Zn concentration and Zn accumulation in wheat grain could be increased by maintaining the high-yield N fertilization and combining the foliar Zn application in the late growth stage, which would improve Zn nutritional quality of wheat grain.

Nutrition, yield and nutrient export in common bean under zinc fertilization in no-till system

ABSTRACT Zinc (Zn) is one of the most deficient plant micronutrients in agricultural crops. The objective of this study was to evaluate plant nutrition, grain yield and nutrient export rate in response to soil and foliar Zn fertilization in common bean (Phaseolus vulgaris L.). Two field experiments in no-till system were carried out using two common bean cultivars, BRS Esteio (black bean) and IPR Campos Gerais (Carioca bean). Treatments were composed of soil Zn application during sowing and foliar Zn spray at flowering stage. Soil Zn application had effect on leaf Zn concentration in IPR Campos Gerais and did not affect grain yield of both cultivars. Foliar Zn spray increased leaf Zn concentration by approximately two times in both cultivars, but negatively affected the grain yield in BRS Esteio. Leaf concentration of N, Ca and S were affected by soil Zn application and leaf concentration of Mn was affected by foliar Zn spray, while leaf concentration of P, K, Mg, Cu and Fe were not influenced by the soil and foliar Zn treatments. In treatments without Zn, the descending order of nutrient export rate from the experimental site was as follows: N > K > P > Ca ≈ S > Mg for macronutrients and Fe > Mn > Cu > Zn for micronutrients. Foliar Zn spray increased the export rate of Zn, P, Ca, Mg, S, Mn, Cu and Fe in IPR Campos Gerais, while soil Zn application resulted in higher export rate of P, K and Mn in BRS Esteio.

Phosphorus-induced zinc deficiency in maize (Zea mays L.) on a calcareous chernozem soil

Abstract A long-term fertilizer experiment was set up on a calcareous chernozem soil with a wheat-maize-maize-wheat crop rotation, as part of the National Long-Term Fertilization Experiments (NLTFE) Network, set up with the same experimental pattern under different soil and agro-climatic conditions in Hungary. The effect of P fertilization on the soil, on maize yields, and on leaf P and Zn contents in the flowering stage were examined in the trials. In certain years, foliar zinc fertilizer was applied, in order to prove that yield losses due to P-induced Zn deficiency can be compensated by Zn application. Calcium-ammonium nitrate, superphosphate and 60% potassium chloride were used as NPK, and Zn-hexamine (in 1991) and Zn-sulphate (in 2006) as foliar Zn fertilizers. In the years since 1970, averaged over 36 maize harvests, treatments N3P1K1 and N4P1K1, involving annual rates of 150 to 200 kg ha−1 N, 100 kg ha−1 K2O and 50 kg ha−1 P2O5, gave the highest yields (8.3 t ha−1 grain on average). As the years progressed, treatments exceeding 50 kg ha−1 P2O5 a year were found to have an increasingly unfavourable effect. Based on the yields of ten cycles (36 maize years), variants P2, P3 and P4 resulted in 16–30–45 t ha−1 grain yield losses in comparison to variant P1. Investigations carried out in 1987, 1991 and 2006 showed that the leaf Zn content on plots with more than 150 to 200 mg kg−1 AL (ammonium lactate)-soluble P2O5 (over 30 mg kg−1 Olsen-P) dropped below 15 mg kg−1 and the P/Zn ratio rose to above 150 or even 250 in the flowering stage in two years. As a consequence of P-induced Zn deficiency, maize grain yields fell by 2 t ha−1 in two of the years investigated and by almost 5 t ha−1 in one year at the P4 level (200 kg ha−1 P2O5 year−1), in comparison to the P1 variant (50 kg ha−1 P2O5 year−1). When 1.2 kg ha−1 foliar Zn was applied in the form of zinc hexamine, 1.7 to 1.8 t ha−1 maize grain yield surpluses were obtained on plots with higher P levels in 1991. In 2006 the P-induced Zn deficiency caused unexpectedly high (almost 5 t ha−1) grain yield losses on plots with higher P levels, so the maize grain yield surpluses obtained in response to 1.2 kg ha−1 foliar Zn application, in the form of zinc sulphate, were as high as 1.6 to 3.8 t ha−1. The data clearly indicate that maize yields are impeded by both poor and excessive P status. Soil and plant analysis may be useful tools for monitoring the nutritional status of plants.

Effect of zinc-biofortified seeds on grain yield of wheat, rice, and common bean grown in six countries.

Seeds enriched with zinc (Zn) are ususally associated with better germination, more vigorous seedlings and higher yields. However, agronomic benefits of high-Zn seeds were not studied under diverse agro-climatic field conditions. This study investigated effects of low-Zn and high- Zn seeds (biofortified by foliar Zn fertilization of maternal plants under field conditions) of wheat (Tritcum aestivum L.), rice (Oryza sativa L.), and common bean (Phaseolus vulgaris L.) on seedling density, grain yield and grain Zn concentration in 31 field locations over two years in six countries. Experimental treatments were: (1) low-Zn seeds and no soil Zn fertilization (control treatment), (2) low-Zn seeds + soil Zn fertilization, and (3) Zn-biofortified seeds and no soil Zn fertilization. The wheat experiments were established in China, India, Pakistan, and Zambia, the rice experiments in China, India and Thailand, and the common bean experiment in Brazil. When compared to the control treatment, soil Zn fertilization increased wheat grain yield in all six locations in India, two locations in Pakistan and one location in China. Zinc-biofortified seeds also increased wheat grain yield in all four locations in Pakistan and four locations in India compared to the control treatment. Across all countries over 2 years, Zn-biofortified wheat seeds increased plant population by 26.8% and grain yield by 5.37%. In rice, soil Zn fertilization increased paddy yield in all four locations in India and one location in Thailand. Across all countries, paddy yield increase was 8.2% by soil Zn fertilization and 5.3% by Zn-biofortified seeds when compared to the control treatment. In common bean, soil Zn application as well as Znbiofortified seed increased grain yield in one location in Brazil. Effects of soil Zn fertilization and high-Zn seed on grain Zn density were generally low. This study, at 31 field locations in six countries over two years, revealed that the seeds biofortfied with Zn enhanced crop productivity at many locations with different soil and environmental conditions. As high-Zn grains are a by-product of Zn biofortification, use of Zn-enriched grains as seed in the next cropping season can contribute to enhance crop productivity in a cost-effective manner.

Foliar application of zinc sulphate and zinc EDTA to wheat leaves: differences in mobility, distribution, and speciation.

Foliar application of zinc (Zn) to crops is an effective way to increase the grain concentration of Zn. However, the development of more efficient foliar Zn fertilizers is limited by a lack of knowledge regarding the distribution, mobility, and speciation of Zn in leaves once it is taken up by the plant. We performed an experiment using radiolabelled Zn (65Zn), and in situ time-resolved elemental imaging using synchrotron X-ray fluorescence microscopy (XFM), to investigate the behaviour of two commonly used Zn foliar fertilizers (Zn sulphate and ZnEDTA) in wheat (Triticum aestivum) leaves. Both experiments showed that Zn had limited mobility in leaves, moving <25 mm from the application point after 24 h. Although limited, the translocation of Zn occurred quickly for both treatments; moving more between 3 h and 12 h after application than between 12 h and 24 h. Speciation analysis using synchrotron-based X-ray absorption near-edge structure (XANES) showed that ZnEDTA was in fact taken up in chelated form and not as ionic Zn (Zn2+). The XANES data also showed that Zn, from both treatments, was then complexed by ligands in the leaf (e.g. phytate and citrate), potentially in response to localized Zn toxicity. The results of the present study provide important insights into the behaviour of commonly used foliar-applied Zn fertilizers, and can be used to optimize current fertilization strategies and contribute to the development of more efficient foliar Zn fertilizers.

Characterization of grain protein content gene (GPC-B1) introgression lines and its potential use in breeding for enhanced grain zinc and iron concentration in spring wheat

At least two billion people around the world suffer from micronutrient deficiency, or hidden hunger, which is characterized by iron-deficiency anemia, vitamin A and zinc deficiency. As a key staple food crop, wheat provides 20% of the world’s dietary energy and protein, therefore wheat is an ideal vehicle for biofortification. Developing biofortified wheat varieties with genetically enhanced levels of grain zinc (Zn) and iron (Fe) concentrations, and protein content provides a cost-effective and sustainable solution to the resource-poor wheat consumers. Large genetic variation for Fe and Zn were found in the primitive and wild relatives of wheat, the potential high Zn and Fe containing genetic resources were used as progenitors to breed high-yielding biofortified wheat varieties with 30–40% higher Zn content. Grain protein content (GPC) determines processing and end-use quality of wheat for making diverse food products. The GPC-B1 allele from Triticum turgidum L. var. dicoccoides have been well characterized for the increase in GPC and the associated pleiotropic effect on grain Zn and Fe concentrations in wheat. In this study effect of GPC-B1 allele on grain Zn and Fe concentrations in wheat were measured in different genetic backgrounds and two different agronomic management practices (with- and without foliar Zn fertilization). Six pairs of near-isogenic lines differing for GPC-B1 gene evaluated at CIMMYT, Mexico showed that GPC-B1 influenced marginal increase for grain Zn, Fe concentrations, grain protein content and slight reduction in kernel weight and grain yield. However, the magnitude of GPC and grain Zn and Fe reductions varied depending on the genetic background. Introgression of GPC-B1 functional allele in combination with normal or delayed maturity alleles in the CIMMYT elite wheat germplasm has the potential to improve GPC and grain Zn and Fe concentrations without the negative effect on grain yield due to early senescence and accelerated maturity.

Effect of foliar application of Cu, Zn, and Mn on yield and quality indicators of winter wheat grain

Micronutrients are part of many crucial physiological plant processes. The combined application of N and micronutrients helps in obtaining grain yield with beneficial technological and consumer properties. The main micronutrients needed by cereals include Cu, Mn, and Zn. The subject of this study was to determine yield, quality indicators (protein content and composition, gluten content, grain bulk density, Zeleny sedimentation index, and grain hardness), as well as mineral content (Cu, Zn, Mn, Fe) in winter wheat grain (Triticum aestivum L.) fertilized by foliar micronutrient application. A field experiment was carried out at the Educational and Experimental Station in Tomaszkowo, Poland. The application of mineral fertilizers (NPK) supplemented with Cu increased Cu content (13.0%) and ω, α/β, and γ (18.7%, 4.9%, and 3.4%, respectively) gliadins in wheat grain. Foliar Zn fertilization combined with NPK increased Cu content (14.9%) as well as high (HMW) and low molecular weight (LMW) glutenins (38.8% and 6.7%, respectively). Zinc fertilization significantly reduced monomeric gliadin content and increased polymeric glutenin content in grain, which contributed in reducing the gliadin:glutenin ratio (0.77). Mineral fertilizers supplemented with Mn increased Fe content in wheat grain (14.3%). It also significantly increased protein (3.8%) and gluten (4.4%) content, Zeleny sedimentation index (12.4%), and grain hardness (18.5%). Foliar Mn fertilization increased the content of ω, α/β, and γ gliadin fractions (19.9%, 9.5%, and 2.1%, respectively), as well as HMW and LMW glutenins (18.9% and 4.5%, respectively). Mineral NPK fertilization, combined with micronutrients (Cu + Zn + Mn), increased Cu and Zn content in grain (22.6% and 17.7%, respectively). The content of ω, α/β, and γ gliadins increased (20.3%, 10.5%, and 12.1%, respectively) as well as HMW glutenins (7.9%).

Biofortification of wheat, rice and common bean by applying foliar zinc fertilizer along with pesticides in seven countries

Rice (Oryza sativa L.), wheat (Triticum aestivum L.) and common bean (Phaseolus vulgaris L.) are major staple food crops consumed worldwide. Zinc (Zn) deficiency represents a common micronutrient deficiency in human populations, especially in regions of the world where staple food crops are the main source of daily calorie intake. Foliar application of Zn fertilizer has been shown to be effective for enriching food crop grains with Zn to desirable amounts for human nutrition. For promoting adoption of this practice by growers, it is important to know whether foliar Zn fertilizers can be applied along with pesticides to wheat, rice and also common bean grown across different soil and environmental conditions. The feasibility of foliar application of zinc sulphate (ZnSO4.7H2O) to wheat, rice and common bean in combination with commonly used five fungicides and nine insecticides was investigated under field conditions at the 31 sites-years of seven countries, i.e., China, India, Pakistan, Thailand, Turkey, Brazil and Zambia. Significant increases in grain yields were observed with foliar Zn/foliar Zn + pesticide (5.2–7.7 % of wheat and 1.6–4.2 % of rice) over yields with no Zn treatment. In wheat, as average of all experiments, higher grain Zn concentrations were recorded with foliar Zn alone (41.2 mg kg−1) and foliar Zn + pesticide (38.4 mg kg−1) as compared to no Zn treatment (28.0 mg kg−1). Though the magnitude of grain Zn enrichment was lesser in rice than wheat, grain Zn concentrations in brown rice were significantly higher with foliar Zn (24.1 mg kg−1) and foliar Zn + pesticide (23.6 mg kg−1) than with no Zn (19.1 mg kg−1). In case of common bean, grain Zn concentration increased from 68 to 78 mg kg−1 with foliar Zn alone and to 77 mg kg−1 with foliar Zn applied in combination with pesticides. Thus, grain Zn enrichment with foliar Zn, without or with pesticides, was almost similar in all the tested crops. The results obtained at the 31 experimental site-years of seven countries revealed that foliar Zn fertilization can be realized in combination with commonly-applied pesticides to contribute Zn biofortification of grains in wheat, rice and common bean. This agronomic approach represents a useful practice for the farmers to alleviate Zn deficiency problem in human populations.

Effects of Zinc Application on Yield and Some Yield Components in Peanut (Arachis hypogaea) in the Easthern Mediterranean Region

The effect of soil and foliar Zn fertilization on two varieties of peanut’s ( Arachis hypogaea ) yield and some yield components were examined in this study. Soil applications of Zn doses were 0, 10, 20 and 40 kg ha -1 whereas 0, 0.5, 1 and 1.5 kg ha -1 Zn were sprayed to leaves. Applications of dose amounts of Zn lead to remarkable increase in yield and 100-seed weight. The effect of Zn treatment found to be statistically important at P<0.01 levels. The highest yield was obtained at COM variety as 6580.0 kg ha -1 with 0.5 kg ha -1 Zn foliar application. The lowest yield was measured at NC-7 variety’s control plot with 3660.0 kg ha -1 in 2007. Foliar application Zn was statistically determined to be important to NC-7 variety peanut’s grain Zn concentration at P<0.05 levels in each year. The economic analyses revealed that 0.5 kg ha -1 foliar application of Zn provided maximum profit with 10271.2 USD Dollars ha -1 .

Long-term effect of high phosphorus doses on zinc status of maize on a non-calcareous loamy soil

The long-term effect of 87.3 kg/ha P on the yield elements and nutrient content of maize was studied at the Na tional Long-Term Fertilization Experiment of the Karcag Research Institute in Hungary. The soil of the experiment site is non-calcareous Luvic Phaeosem, and its soluble phosphorus (P) and zinc (Zn) content in 0–20 cm soil layer are: ammonium lactate P: 141.1 mg/kg and diethylene triamine pentaacetic acid (DTPA) Zn: 0.85 mg/kg, respectively. The effect of foliar Zn fertilization was studied at three levels of nitrogen (150, 200 and 250 kg/ha) and under 87.3 kg/ha P and 82.6 kg/ha K application in four replications. The applied Zn amount was 700 g/ha. We measured the grain yield and the thousand-kernel weight. Leaf and grain samples were analyzed for phosphorus, zinc, potassium, calcium, magnesium and manganese content. Foliar Zn application did not increase the yield significantly, but it enhanced the thousand-kernel weight. The element content did not change significantly – neither in leaves nor in kernels. Under the examined habitat circumstances even the long-term application of 87.3 kg/ha P dosage did not cause Zn deficiency to such an extent which would lead to significant yield depression of maize.

Foliar Fertilization with Zinc in Pecan Trees

The objective of this study was to assess the changes in leaflet zinc (Zn), leaf nutritional state, vegetative and physiological parameters, and yield quality in pecan trees sprayed with different Zn compounds. Eight-year-old ‘Western Schley’ pecan trees grafted to native seedlings were treated with ZnNO3 (100 mg·L−1 Zn), Zn-EDTA (50, 100, and 150 mg·L−1 Zn), and Zn-DTPA (100 mg·L−1 Zn) and compared with the Zn-untreated control. After 3 years of evaluation, the trees with the best appearance were those treated with ZnNO3 (100 mg·L−1 Zn) and Zn-DTPA (100 mg·L−1 Zn), which showed leaf Zn concentration increases of 73% and 69%, respectively, when compared with the controls. The chlorophyll values of the Zn-treated trees reached 46 SPAD units, equivalent to 43 mg·kg−1 dry weight (DW) of chlorophyll compared with values of 22 mg·kg−1 DW in Zn-deficient leaves. On a leaf area basis, chlorophyll value was 37% lower under Zn deficiency conditions than that of Zn-treated trees. Nut quality was unaffected by the Zn treatments. Data suggest that Zn-DTPA and Zn-NO3 are good options to carry out foliar Zn fertilization in pecan trees.

Biofortification and Bioavailability of Rice Grain Zinc as Affected by Different Forms of Foliar Zinc Fertilization

BackgroundZinc (Zn) biofortification through foliar Zn application is an attractive strategy to reduce human Zn deficiency. However, little is known about the biofortification efficiency and bioavailability of rice grain from different forms of foliar Zn fertilizers.Methodology/Principal FindingsFour different Zn forms were applied as a foliar treatment among three rice cultivars under field trial. Zinc bioavailability was assessed by in vitro digestion/Caco-2 cell model. Foliar Zn fertilization was an effective agronomic practice to promote grain Zn concentration and Zn bioavailability among three rice cultivars, especially, in case of Zn-amino acid and ZnSO4. On average, Zn-amino acid and ZnSO4 increased Zn concentration in polished rice up to 24.04% and 22.47%, respectively. On average, Zn-amino acid and ZnSO4 increased Zn bioavailability in polished rice up to 68.37% and 64.43%, respectively. The effectiveness of foliar applied Zn-amino acid and ZnSO4 were higher than Zn-EDTA and Zn-Citrate on improvement of Zn concentration, and reduction of phytic acid, as a results higher accumulation of bioavailable Zn in polished rice. Moreover, foliar Zn application could maintain grain yield, the protein and minerals (Fe and Ca) quality of the polished rice.ConclusionsFoliar application of Zn in rice offers a practical and useful approach to improve bioavailable Zn in polished rice. According to current study, Zn-amino acid and ZnSO4 are recommended as excellent foliar Zn forms to ongoing agronomic biofortification.

Physiological limits to zinc biofortification of edible crops.

It has been estimated that one-third of the world’s population lack sufficient Zn for adequate nutrition. This can be alleviated by increasing dietary Zn intakes through Zn biofortification of edible crops. Biofortification strategies include the application of Zn-fertilizers and the development of crop genotypes that acquire more Zn from the soil and accumulate it in edible portions. Zinc concentrations in roots, leaves, and stems can be increased through the application of Zn-fertilizers. Root Zn concentrations of up to 500–5000 mg kg−1 dry matter (DM), and leaf Zn concentrations of up to 100–700 mg kg−1 DM, can be achieved without loss of yield when Zn-fertilizers are applied to the soil. It is possible that greater Zn concentrations in non-woody shoot tissues can be achieved using foliar Zn-fertilizers. By contrast, Zn concentrations in fruits, seeds, and tubers are severely limited by low Zn mobility in the phloem and Zn concentrations higher than 30–100 mg kg−1 DM are rarely observed. However, genetically modified plants with improved abilities to translocate Zn in the phloem might be used to biofortify these phloem-fed tissues. In addition, genetically modified plants with increased tolerance to high tissue Zn concentrations could be used to increase Zn concentrations in all edible produce and, thereby, increase dietary Zn intakes.