Foliar Application Of Zn Research Articles

Iron and zinc biofortification and bioaccessibility in carrot ‘Dordogne’: Comparison between foliar applications of chelate and sulphate forms

Hidden hunger is a worldwide problem, with iron (Fe) and zinc (Zn) deficiency being the most common causes of mineral deficiency. Vegetable biofortification is an effective strategy to fight mineral deficiency, especially when commonly consumed vegetables are utilized, as in the case of carrots. This biofortification study aimed to investigate the response of the off-season carrot cv. Dordogne to different forms of foliar applications of Fe and Zn. The crop received four applications of both minerals, either in the form of inorganic salt (FeSO4 and ZnSO4) or chelated forms (Fe-DTPA and Zn-EDTA), at a concentration of 6 mM of these elements. FeSO4 was efficient in increasing the Fe concentration in carrots (by 52%), while Fe-DTPA caused no significant differences. Regarding Zn, both forms were effective in the biofortification, but Zn-EDTA proved to be more efficient in increasing root Zn concentration (+94%) than ZnSO4 (+57%). Bioaccessibility data, measured after in vitro digestion, showed that biofortified carrots with the chelated forms retained a full bioaccessibility of the minerals (around 100% as in control carrots). However, the sulfate-biofortified carrots showed reduced bioaccessibility values (60% and 80% for Fe and Zn, respectively). The results also showed an increase in dry matter, total nitrogen content and antioxidant activity in plants treated with Zn-EDTA. This trend paralleled the increase of polyphenols and total carotenoids content, suggesting the overall benefit of biofortification strategies conducted in the field. In conclusion, our study revealed that chelated forms of both minerals are preferable in the biofortification programs of carrots.

Application of zinc and iron for higher productivity and agronomic use efciency of chickpea (Cicer arietinum) varieties

An experiment was conducted during the winter season of 2017–18 and 2018–19 at the University of Agricultural Sciences, Dharwad, Karnataka to evaluate the effect of Zn and Fe on productivity and agronomic use efficiency of chickpea (Cicer arietinum L.). In this experiment, 2 varieties of chickpea were applied with Zn and Fe through foliage in the form of sulphates at different stages and also tested with the application to soil and via a seed treatment. Variety ‘GBM 2’ gave higher yield, Zn and Fe content in seed than ‘JG 11’. However, ‘JG 11’ was more efficient in using native Zn and Fe, as it had shown higher Zn and Fe agronomic efficiency under all the methods compared to ‘GBM 2’. Foliar application of Zn and Fe proved better method of application than soil application or seed treatment of Zn or individual application of Zn or Fe. Yield increase was 20.2 and 19.35% higher in foliar application of Zn and Fe over the control respectively, in 2017–18 and 2018–19. Foliar application of Zn with Fe recorded 22.29 and 11.30% higher Zn accumulation in seed over soil application of micronutrients in 2017–18 and 2018–19 respectively.

Grain yield and quality of wheat are improved through post-flowering foliar application of zinc and 6- benzylaminopurine under water deficit condition.

Zinc (Zn) as an essential micronutrient and cytokinin as phytohormone not only regulate plant growth but also play fundamental roles in plant tolerance against drought stress. Understating the function and the role of cytokinin in combined with an essential micronutrient, Zn, could improve the choice of a sustainable strategy for improvement of plant drought stress. The objective of this field research was to determine the effect of post-flowering foliar application of ZnSO4 and 6-benzylaminopurine (6-BAP) on grain yield and quality of winter wheat under water deficit condition. Experiments were conducted under filed condition. Drought was imposed by with holding irrigation at the beginning of flowering till the signs of temporary wilting/leaf rolling appeared, after which all plots were irrigated to field capacity. The foliar treatment consisted of (1) foliar application of water, as control treatment; (2) foliar application of 10 g ha-1 6-BAP; (3) Foliar application of 20 g ha-1 6-BAP; (4) Foliar application of 10 g ha-1 6-BAP plus foliar application of 6 kg ha-1 ZnSO4 solution and (5) foliar application of 10 g ha-1 6-BAP plus foliar application of 6 kg ha-1 ZnSO4 solution 2 days before drought imposition. Data were collected on grain and straw yield, yield attributes, harvest index, flag leaf fresh matter and dry matter weight, TaCKX6-D1 expression, phytic acid content in grains, mycorrhiza colonization rate and succinate dehydrogenase (SD) activity. According to ANOVA, the factor 'Zn' significantly affected leaf relative water content (p < 0.001). Relative water content for plants foliar applied with 6-BAP was not statistically significant. Applying Zn increased yield, straw dry weight, and kernel weight relative to plants sprayed with water alone. Increased grain yield due to foliar application of Zn was associated with decrease in cytokinin oxidase/dehydrogenase (TaCKX) and increase in kernel weight. Results showed that the drought stress significantly decreased 1000-grain weight that was accompanied with over-expression of cytokinin oxidase/dehydrogenase (TaCKX). Foliar application of Zn increased the concentration of Zn in grains. The experimental data on the zinc content of grain indicated no significant difference between the 6-BAP at 10 mg L-1 and control treatment. The phytate to Zn molar ratio was significantly affected by foliar applied Zn, but not significantly by applied 6-BAP. In the present study, SD activity of the hyphae of indigenous arbuscular mycorrhizal fungi (IAMF) associated with plant roots was also assayed. Results disclose that SD activity of IAMF was significantly affected by Zn treatments during grain filling stages. In summary, both foliar applied Zn and 6-BAP had the significant effects on all measured parameters in winter wheat. However, spike number, harvest index and mycorrhizal colonization rate were neither significantly affected by Zn nor 6- BAP. Foliar application of Zn at 0.6% (6 kg ha-1) and higher 6-BAP (20 mg L-1 m-2) promoted wheat growth and performances under imposed drought stress condition. Plant that only foliar sprayed with water showed higher level of TaCKX6-D1 expression as compared to Zn treated plants, indicating these plants were more affected by imposed drought relative to those plants treated with Zn. The results of this study provides evidence that a combination of Zn and 6-BAP could be an effective in improvement of drought tolerance of wheat and prevents grain yield from further reduction in terms of quality and quantity due to drought stress.

Physiochemical response of Cicer arietinum to zinc-containing mesoporous silica nanoparticles under water stress.

Chickpea is an important food legume cultivated in semiarid regions, where water scarcity and nutrient deficiencies negatively affect crop production. This study aimed to investigate the effect of zinc and silicon from different sources, including bulk and nanostructures, on various biochemical traits of chickpea plants grown under field conditions in Maragheh, Northwest Iran. The main experimental factor consisted of three soil moisture levels: irrigation to 90% of field capacity (FC), 60% FC, and 30% FC. The subplots were assigned for foliar application of different fertilizers: control (distilled water), zinc sulfate (ZnSO), silicon dioxide nanoparticles (SiO2 NPs), ZnSO + SiO2 NPs, and zinc-containing mesoporous silica nanoparticles (MSNPs -Zn). The results showed that although decreased soil moisture had a negative impact on several biochemical processes, foliar application of Zn and Si in both conventional bulk and nanostructure significantly affected plant antioxidant system, plasma membrane integrity, and the concentrations of photosynthetic pigments and compatible solutes. However, the most inducing effects on catalase, ascorbate peroxidase, guaiacol peroxidase, superoxide dismutase, and anthocyanin were observed with the foliar spray of MSNPs-Zn and ZnSO + SiO2 under 60% FC. Moreover, foliar spray of MSNPs-Zn alleviated the negative effects of water deficit stress on photosynthetic pigments (chlorophyll a /b and carotenoid content). Water stress significantly induced the accumulation of free proline in the leaves. Overall, the results indicated that foliar spray of MSNPs -Zn, especially under 60% FC, improved the plant's defense system, scavenged reactive oxygen species, and enhanced the accumulation and stability of pigments, thereby mitigating the effects of drought stress.

Enhancing Grain Yield and Zinc Content in Bread Wheat Using Zinc and Nitrogen Application under Supplementary Irrigation Treatments

Wheat (Triticum aestivum L.) is one of the crops that has great importance in human and animal nutrition. Nutrient management can improve the nutritional value and grain yield in bread wheat. Therefore, this study was conducted to assessment the effect of Zinc (Zn) levels as well as the interactions with Nitrogen (N) and irrigation regimes on yield, yield components and Zn content in bread wheat grain. To this purpose, an experiment was performed in a split-split plot design with four replications, which supplementary irrigation (no irrigation, irrigation at stem elongation and irrigation at the stage of grain filling) as the main plot, Zn levels as split-plot (no spraying of Zn and Spraying Zn with a concentration of 5%) and nitrogen consumption levels (nitrogen-free, half the normal dosage and normal nitrogen consumption) as split-split factors. The results showed that the grain yield and yield components affected by the applied treatments. The highest grain yield (646 g/m2 ) and Zn concentration (32.69%) observed in spraying Zn at 5% concentration supplemented with irrigation at the grain filling stage with normal N application. Also, Zn content of grain was increased by Zn foliar application. Furthermore, the grain yield significantly correlated with Zn content, Harvest index (HI), seed filling rate (SFR), thousand seed weight (TKW) and seed number per spike (SNS) traits. The highest grain yield was obtained in supplementary irrigation in grain filling stage indicating importance of supplementary irrigation in this stage. In general, the results of this study showed that the grain yield and quality in bread wheat could be increased by supplementary factors.

Foliar application of graphene oxide, Fe, and Zn on Artemisia dracunculus L. under salinity

Salinity is an abiotic stressor that greatly influences crop growth and yield. Scientists are always exploring diverse methods to combat salinity depression. Here, we conducted a greenhouse experiment to study the effects of NaCl salinity (0, 50, and 100 mM) under the foliar spray with zinc-oxide, nano zinc-oxide, iron-chelate, magnetized-Fe, and graphene-oxide on tarragon. The results revealed that the treatment with foliar spray of graphene showed the highest K+/Na+. Salinity of 50 and 100 mM × all foliar applications increased superoxide dismutase activity, whereas 100 mM NaCl raised the malondialdehyde content to its highest level. All salinity levels × Zn foliar spray improved the catalase activity. The foliar spray and salinity experiment exposed to Zn-treated plants attained the highest contents of essential oils. Proline and total phenolics showed the greatest amounts with 50 and 100 mM of NaCl, respectively. The GC/MS analysis revealed 38 compounds in the oil of Artemisia dracunculus L. as estragole (81-91.8 %) was the most dominant constituent. The highest amounts of estragole were found at 50 and 100 mM NaCl foliar sprayed with ZnO. Cis-Ocimene (0.1-6.4 %) was another major constituent with a high variation between the treatments. The highest cis-ocimene content was recorded at 100 mM NaCl × foliar Fe-chelated and in the graphene treatment. Overall, salinity adversely affected the physiological responses of tarragon; however, foliar spray with both forms of Fe and Zn partially ameliorated the adverse salinity effects.

Nutritional enrichment of tomato (Lycopersicon esculentum L.) through Zinc (Zn) and Boron (B) Fertilization

The influence of micronutrients namely zinc (Zn) and boron (B) with or without farmyard manure (FYM) on growth, yield and quality parameters viz. ascorbic acid and carotene content of tomato was evaluated. A field experiment was conducted with graded doses of Zn (soil and soil + foliar application) and B (soil application) application with or without FYM for the two consecutive years (2012 and 2013). Results revealed that application of Zn and B significantly enhanced fruit yield and different growth parameters as well as plant tissue concentration of Zn and B in tomato. The highest increase in fruit yield over control (27.6%) was observed with the conjoint application of Zn (soil + foliar), B (2.0 kg ha−1) and FYM. Soil application of Zn at higher doses (10 kg ha−1) as well as its application through both soil + foliar method has an edge over control or its application at comparatively lower doses in increasing the fruit yield of tomato. Results further revealed that combined application of Zn and B can significantly increase the important quality parameters viz. carotene and ascorbic acid content in tomato. Such increase in carotene content to the tune of 25 and 35% and ascorbic acid content to the tune of 7 and 30% over control were observed with soil + foliar application of Zn and 2 kg ha−1 B, respectively. Therefore, optimization of Zn and B doses can improve the yield and quality of tomato as well as helps in correcting the micronutrients malnutrition vis-à-vis nutritional disorders in humans by enriching the antioxidants.

Combined foliar application of Zn and Fe increases grain micronutrient concentrations and alleviates water stress across diverse wheat species and ploidal levels

This study aimed to examine the reaction of several wheat species with different ploidy levels to foliar application of zinc (Zn) and iron (Fe) under different water regimes. Thirty-five wheat genotypes, including nineteen tetraploids from ten different species, ten hexaploids from five species, and six diploids from three species, were evaluated in the field over two moisture regimes with the following four treatments: control, foliar Zn application, foliar Fe application, and foliar Zn + Fe application. The experiments were conducted according to a split-plot scheme in a randomized complete block design with two replications in each moisture regime. Water stress negatively affected all measured traits, except grain Zn and Fe content. Combined foliar application of Zn + Fe significantly increased yield and alleviated yield reduction caused by water stress. Applying Zn and Fe significantly increased both micronutrient content in grains under both moisture conditions. Tetra and hexaploid species yielded nearly four times as much grain as unimproved diploid species and were less affected by water stress. All ploidy levels responded almost similarly to Zn and Fe treatments, with the combined application being as effective as each element separately. The highest yield increase in response to combined application of Zn + Fe under the two moisture conditions and the highest grain Zn content in response to Zn application under water stress was observed in hexaploid wheat. Combined foliar application of Zn and Fe increases grain Zn and Fe and alleviates water stress's adverse effects on all wheat ploidy levels, making biofortification cost-effective.

Impact of Foliar Application of ZnO and Fe3O4 Nanoparticles on Seed Yield and Physio-Biochemical Parameters of Cucumber (Cucumis sativus L.) Seed under Open Field and Protected Environment vis a vis during Seed Germination.

Nutritionally rich cucumber seeds remain in demand in the agricultural, health and cosmetic sectors as they are essential for a successful crop stand establishment and seed-based products. However, the production of cucumber seeds is impeded by source limitation and nutrient deficiency. The foliar application of micronutrients can supplement this deficiency and overcome the physiological setback. An experiment was undertaken to compare the impacts of the foliar application of Fe and Zn, as nanoparticles and fertilizers, on the yield and seed quality of cucumber under open and protected environments. A foliar spray of nano-ZnO (ZnNPs) and nano-Fe3O4 (FeNPs) at 100, 200 and 300 mg L-1, as well as ZnSO4 and FeSO4 as fertilizer (0.5%), was conducted at the vegetative stage and pre- and post-flowering stages. The NPs had a greater efficacy in an open field than in the protected (naturally ventilated poly house) environment. The application of both NPs increased seed yield (51.7-52.2%), total chlorophyll content (15.9-17.3%) and concentration of Zn and Fe in the fruit and the seed, by 2.0-58.5% and 5.0-30.5%, respectively. A significant increase in starch, soluble proteins, soluble sugars and oil content was observed in the seeds from the NP treated plants. NP treatment also enhanced the germination-related parameters, such as percent germination (16.8-17.0%), rate of germination (18.0-22.2%) and seedling vigor (59.8-72.6%). The biochemical characterization showed a significant improvement in the seed water uptake and the activity of hydrolytic enzymes (amylase and protease) in the germinating seed. The involvement of reactive oxygen species (superoxide anion and hydrogen peroxide) and antioxidant enzymes (Superoxide dismutase, Catalase and Peroxidase) in the germination process was indicated by an increase in their activities in the seeds from NP treated plants. Hence, the study proposes the potential benefit of the foliar application of 300 mg L-1 ZnNPs and 200 mg L-1 FeNPs at crucial stages of plant growth to improve the yield and seed quality in cucumbers.

Zinc agronomic biofortification of staple crops may be a cost-effective strategy to alleviate zinc deficiency in Ethiopia.

Inadequate dietary zinc (Zn) supplies and Zn deficiency (ZnD) are prevalent in Ethiopia, where cereals are major dietary sources, yet low in bioavailable Zn. Zinc agronomic biofortification (ZAB) of staple crops through application of Zn fertilizers may contribute to alleviating ZnD. However, large-scale promotion and adoption of ZAB requires evidence of the feasibility and public health benefits. This paper aimed to quantify the potential cost-effectiveness of ZAB of staple crops for alleviating ZnD in Ethiopia. Current burden of ZnD among children in Ethiopia was quantified using a disability-adjusted life years (DALYs) framework. Evidence on baseline dietary Zn intake, cereal consumption, and fertilizer response ratio was compiled from existing literature and secondary data sources. Reduction in the burden of ZnD attributable to ZAB of three staple cereals (maize, teff, and wheat) via granular and foliar Zn fertilizer applications was calculated under optimistic and pessimistic scenarios. The associated costs for fertilizer, labor, and equipment were estimated in proportion to the cropping area and compared against DALYs saved and the national Gross Domestic Product capita-1. An estimated 0.55 million DALYs are lost annually due to ZnD, mainly due to ZnD-related mortality (91%). The ZAB of staple cereals via granular Zn fertilizer could reduce the burden of ZnD by 29 and 38% under pessimistic and optimistic scenarios, respectively; the respective values for ZAB via foliar application were 32 and 40%. The ZAB of staple cereals via granular fertilizer costs US$502 and US$505 to avert each DALY lost under optimistic and pessimistic scenarios, respectively; the respective values for ZAB via foliar application were US$226 and US$ 496. Foliar Zn application in combination with existing pesticide use could reduce costs to US$260-353 for each DALY saved. Overall, ZAB of teff and wheat were found to be more cost-effective in addressing ZnD compared to maize, which is less responsive to Zn fertilizer. ZAB of staple crops via granular or foliar applications could be a cost-effective strategy to address ZnD, which can be integrated with the existing fertilizer scheme and pesticide use to minimize the associated costs.

Sugarcane Productivity as a Function of Zinc Dose and Application Method

Sugarcane is one of the main crops in Brazilian agriculture. It has high economic and productive potential, but its current productivity is still lacking due to poor nutritional management in both the soil and the plant. Zinc (Zn) directly affects tillering and plant growth, which are critical factors to sugarcane productivity and ratoon longevity. Thus, this research aimed to evaluate the effects of Zn chelate doses (185, 260, and 330 g ha−1) and two application methods (furrow and foliar applications) on the tillering, yield, and quality of sugarcane. The Zn chelate fertilization via furrow at a dose of 330 kg ha−1 provided increases of 13.59%, 17.6%, and 17.0% in stalk height (SH), stalk (TSH) productivity, and sugar (TPH) productivity, respectively. In contrast, Zn foliar application at a dose of 260 g ha−1 provided increases of 3.71%, 20.7%, and 17.0% in SH, TSH, and TPH, respectively. The optimal Zn chelate fertilization in sugarcane cultivation can be performed at a dose of 330 g ha−1 via furrow application at planting or at a dose of 260 g ha−1 via foliar application 145 days after planting.

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.

Effects of foliar zinc applications on some yield parameters and essential oil constituents of the mastic tree (Pistacia lentiscus var. chia Duham.)

Mastic tree (Pistacia lentiscus var. chia Duham.) is an important medicinal aromatic plant which is being cultivated without any regular fertilization generally. Foliar Zn applications have great importance for many commercial plant species because of their important role in metabolic activities. In this study, the effects of foliar ZnSO4 sprayings (0, 0.2, 0.4, 0.8%) applied at 50% and 100% leafing stages, on some yield parameters and essential oil composition of mastic tree were assessed. A field experiment was carried out for two consecutive years at Ege University, Turkey. Mastic resin yield was more than doubled with 0.8% Zn particularly in the second year. The highest leaf Zn content was measured as 187.8 mg l−1 with 0.8% zinc spraying while it was 35.4 mg l−1 in unsprayed trees at 100% leafing in the first year. Leaf essential oil and α-tocopherol contents were not significantly influenced by different Zn levels and leafing stages in both years. As for the major essential oil constituents, β-myrcene (62.4%), germacrene-D (14.3%), α-terpinenyl acetate (5.52%), t-caryophyllene (2.1%) and α-pinene (1.4%) were determined. Zinc sprayings increased the β-myrcene, germacrene-D and α-pinene contents particularly at 100% leafing in the first year. In mastic tree two consecutive applications of Zn seems to be necessary for reaching to desirable leaf Zn contents. Application of 0.8% Zn or more would be proper to increase the contents of most parameters assessed.

Rendimiento, rentabilidad y eficiencia agronómica de nitrógeno en maíz de secano con fertilización foliar complementaria de Zn y Mo

The research aimed to evaluate the effect of complementary foliar applications of Zn and Mo on the yield, profitability, and agronomic efficiency of nitrogen in rainfed maize. The work was carried out during the rainy seasons of 2020 and 2021 in the Carrizal river valley, Manabí, Ecuador. The treatments evaluated were: NPK soil fertilization supplemented with foliar application of Zn and Mo (T1) and NPK soil fertilization without foliar application of Zn and Mo (T2). Grain yield (RG), agronomic efficiency of N (EAN), and the net economic benefit of fertilization (BEN) were recorded. Data were analyzed with Student's t-test for paired observations. Treatment T1 increased the RG by 15.58% and 14.03% during 2020 and 2021, respectively, concerning treatment T2. Similarly, the T1 treatment increased the EAN by 28.30% and 24.60% in the 2020 and 2021 seasons, respectively, concerning the T2 treatment. Finally, treatment T1 produced the highest BEN, with an increase of 23.05% and 16.37%, during 2020 and 2021, respectively, about treatment T2. Complementary foliar fertilization with Zn and Mo enhanced the effect of NPK soil fertilization and increased yield, profitability, and EAN in rainfed maize.

Optimizing zinc foliar spray for zinc fortification and yield improvement in wheat

Aim: To investigate the field efficacy of foliar applied Zn at variable doses and time of application for enriching Zn concentration in different milling fractions of wheat grain and Zn loading capacity of different grain milling fractions. Methodology: A field experiment was carried out involving four graded Zn sprays (0.1, 0.2, 0.3, and 0.4%) with water-spray as control, applied at flowering stage of wheat crop at weekly intervals.Harvested wheat grains were pearled into nine fractions from the surface to the center using two rice polishers (JNMJ7 and JNMJ6). The rice polishers were able to separate the wheat grain fractions. Zinc concentration in the whole grain and grain fractions (layer 1 to layer 9) of wheat samples were digested with di-acid mixture and estimated on an Atomic Absorption Spectrophotometer. Results: Foliar application of Zn (0.3-0.4% Zn) at 14 or 21 days after flowering (DAF) increased Zn in whole grain by 15.3-17.0 mg kg-1 (p &lt; 0.05). Zn spray enhanced Zn concentration in all the grain layers i.e. 1st to 9th layers (L), albeit in endosperm layers (L3-L8) by a maximum of 10.8 mg kg-1. However, Zn loading capacity differed in different fractions and was in the order L8&gt;L6&gt;L7&gt;L5≥ L4≥L3 (p &lt; 0.05). Interpretation: Foliar spray of Zn in wheat with optimum dose (0.3-0.4%) and time (14-21 DAF) can enhance Zn acquisition and loading to grain endosperm with a higher yield. Key words: Foliar spray, Grain yield, Wheat, Zinc biofortification

Effects of Foliar Fertilization on Nutrient Uptake, Yield, and Fruit Quality of Pomelo (Citrus grandis Osbeck) Grown in the Mekong Delta Soils

Foliar application is a popular technique to supply mineral nutrients to crops. It also enhances nutrient use efficiencies, especially under limited soil fertility or restricted environmental conditions. This study aimed to evaluate the influence of foliar application of phosphorus (P) with potassium (K), magnesium (Mg), and zinc (Zn) on the nutrient uptake, yield, and fruit quality of pomelo. The experiments were conducted between 2018 and 2021 in three different sites of alluvial soils, including four treatments, namely, control (without foliar fertilization), FF1 (containing P, K, and Mg), FF2 (P, K, Mg, and Zn), and FF3 (Zn). The results indicated that the P, K, and Mg concentrations in leaves and fruits were significantly enhanced after the spraying of solutions FF1 and FF2 compared with the control and FF3. The application of FF1 and FF2 greatly improved the fruit quality, and the fruit yield response was as high as 4.0-5.0 t ha−1. Foliar Zn application (FF3) increased the Zn concentration in leaves, but there was no improvement in fruit Zn content, fruit quality, and yield compared to the control treatment. The results indicate that FF1 or FF2 could be used as a sustainable fertilizer strategy for pomelo trees because of its ability to improve the leaf and fruit nutrient concentration and enhance the fruit quality and productivity of pomelo.

Efficacy of Nitrogen and Zinc Application at Different Growth Stages on Yield, Grain Zinc, and Nitrogen Concentration in Rice

Zinc (Zn) is an essential element involved in human metabolism, which can be supplied by an appropriate diet. Enhancing Zn enrichment in rice grains through agronomic biofortification is advocated as an immediate and effective approach to combat micronutrient malnutrition in hu-man. It has been well-documented that high grain Zn accumulation in rice can be achieved by Zn fertilizers management. This study evaluated the effects of foliar nitrogen (N) and Zn applied at the flowering and milky stages of brown rice plants with and without soil Zn application. A glasshouse pot experiment was conducted using a completely randomized design with four replicates. Soil Zn in the form of ZnSO4 was applied at 0 and 50 kg ha−1. Foliar fertilizer of 1% urea along with 0.5% ZnSO4 was applied and assigned as (1) nil foliar N and Zn (N0Zn0), (2) foliar N with nil Zn (N+Zn0), (3) nil foliar N with foliar Zn (N0Zn+), and (4) foliar N and Zn (N+Zn+) at flowering and milky stages. Foliar application of N and Zn increased grain yield and yield components in both soil Zn conditions. Grain Zn concentration in brown rice was the highest when foliar N and Zn were applied under nil soil Zn conditions; however, grain N concentration decreased by 13.1–28.5% with foliar application at flowering and 18.8–28.5% with application at the milky stage. The grain Zn content was increased by foliar application of N0Zn+ and N+Zn+ at flowering and milky stages. Applying foliar N and Zn at flowering or milky stages tended to increase the grain N content when Zn was applied to the soil, while nil soil Zn decreased the N content by 26.8% at flowering and milky stages under N0Zn+. The results suggest that the milky stage is the most suitable for foliar application of Zn for increasing (i) grain yield and (ii) N and Zn concentrations in brown rice without having a dilution effect.

Rice growth improvement, bio-fortification, and mitigation of macronutrient requirements through foliar application of zinc and iron- glycine chelate and zinc sulfate

Foliar application of Zinc (Zn) and Iron (Fe) fertilizers is known to be an effective solution to enhance rice grain yield and bio-fortification. The objectives of the current field experiment were to evaluate the effects of the foliar application of 0.5, 1, and 1.5 kg ha−1 of Zn and Fe glycine amino acid chelates and ZnSO4 on rice grain yield, protein, Zn, and Fe content of head rice (Hashemi cultivar) under both in the recommended and ½ of the recommended dose of NPK. The highest increase in the grain yield was recorded at 0.5 kgha−1 Fe-glycine amino acid chelate by about 29.2%. The maximum increase in protein and Zn content of head rice were recorded at 1.5 kg ha−1 of glycine amino acid-Zn chelate by about 10.5 and 22.3%, respectively. The most effective treatment to enhance the Fe content of head rice was the foliar application of 1.5 kg ha−1 of glycine amino acid-Fe chelate by about 32.6%. Interestingly, the foliar application of 1 kg ha−1 Zn-glycine amino acid chelate plus 1 kg ha−1 Fe-glycine amino acid chelate at the plots that received ½ of recommended NPK increased the grain yield, and protein, Zn and Fe content of head rice compared to control by about 7%, 18.5, 7.5, and 26.2, respectively. Therefore, regardless of rates and types, foliar application of Zn and/or Fe could enhance both rice yield, protein, Zn, and Fe content of head rice both in plots that received recommended and ½ of the recommended dose of NPK.

Interactive Effects of Molybdenum, Zinc and Iron on the Grain Yield, Quality, and Nodulation of Cowpea (Vignaunguiculata (L.) Walp.) in North-Western India

Micronutrient deficiency is a major constraint for the growth, yield and nutritional quality of cowpea which results in nutritional disorders in humans. Micronutrients including molybdenum (Mo), iron (Fe) and zinc (Zn) play a pivotal role in crop nutrition, and their role in different metabolic processes in crops has been highlighted. In order to increase the nutritional quality of cowpea, a field experiment was conducted for two years in which the effect of Mo along with iron (Fe) and zinc (Zn) on productivity, nitrogen and micronutrient uptake, root length and the number of nodules in cowpea cultivation was investigated. It was found that the foliar application of Fe and Zn and their interaction with Mo application through seed priming as well as soil application displayed increased yield, nutrient concentration, uptake and growth parameters which helped to enhance the nutritional quality of cowpea for consumption by the human population. The results of the above experiments revealed that among all the treatments, the soil application of Mo combined with the foliar application of 0.5% each of FeSO4·7H2O and ZnSO4·7H2O (M2F3 treatment) enhanced the grain and stover yield of cowpea, exhibiting maximum values of 1402 and 6104.7 kg ha−1, respectively. Again, the M2F3 treatment resulted in higher Zn, Fe and Mo concentrations in the grain (17.07, 109.3 and 30.26 mg kg−1, respectively) and stover (17.99, 132.7 and 31.22 mg kg−1, respectively) of cowpea. Uptake of Zn, Fe and Mo by the grain (25.23, 153.3 and 42.46 g ha−1, respectively) as well as the stover (104.2, 809.9 and 190.6 g ha−1, respectively) was found to be maximum for the M2F3 treatment. The root length (30.5 cm), number of nodules per plant (73.0) and N uptake in grain and stover (55.39 and 46.15 kg ha−1) were also higher for this treatment. Overall, soil application of Mo along with the foliar application of FeSO4·7H2O (0.5%) and ZnSO4·7H2O (0.5%) significantly improved yield outcomes, concentration, uptake, root length, nodules plant−1 and N uptake of cowpea to alleviate the micronutrient deficiency.

Zinc Nutrition Responses to Agronomic and Yield Traits, Kernel Quality, and Pollen Viability in Rice (Oryza sativa L.).

Rice (Oryza sativa L.) is one of the major cereal crops worldwide with wheat and maize. A total of two field experiments were performed to evaluate the response of some rice cultivars to various foliar zinc (Zn) concentrations based on different measurements, such as agronomic, yield, yield compounds, and grain technological parameters. The experimental layout was a split plot in three replicates; the five rice cultivars (Skaha 101, Giza178, Yasmeen, Fourate, and Amber 33) were distributed in the main plots while the four foliar applications of Zn (1,500, 2,000, 2,500 mg/L besides spray water) were occupied the sub-plots. The findings showed significant differences among the five rice cultivars regarding plant height, grain yield, straw yield, biological yield, harvest index, 1,000-grain weight, panicle length, protein percentage, and grain Zn content. There is a significant effect of Zn on all plant attributes. A significant interaction between rice cultivars and foliar application of Zn was observed, whereas fertilizing Giza 178 with foliar application of Zn at the rate of 2,500 mg/L achieved the highest mean values of grain yield and straw yield, biological yield, harvest index, 1,000-grain weight, panicle length, protein %, and Zn content followed by Sakha 101 with Zn application at the rate of 2,000 mg/L, respectively, in both seasons. The rice cultivars significantly differed in hulling (%), broken (%), hardness, grain length, shape, amylose (%), gel consistency, and gelatinization temperature. Unfortunately, the commercial Zn product used was genotoxic to pollen grains with a higher rate of Zn. Aberrations were observed such as stickiness, ultrastructural changes in the exterior and interior walls, partially or fully degenerated grains, and shrunken and unfilled grains. This study concluded that using Zn application at the rate of 2,000 mg/L to protect human and environmental health, the side effects and toxicity of the local commercial Zn product market should be investigated before making recommendations to farmers.