Comparison study of zinc nanoparticles and zinc sulphate on wheat growth: From toxicity and zinc biofortification

Nanofertilizers for agricultural and environmental sustainability

Indiscriminate use of chemical fertilizers in the agricultural production systems to keep pace with the food and nutritional demand of the galloping population had an adverse impact on ecosystem services and environmental quality. Hence, an alternative mechanism is to be developed to enhance farm production and environmental sustainability. A nanohybrid construct like nanofertilizers (NFs) is an excellent alternative to overcome the negative impact of traditional chemical fertilizers. The NFs provide smart nutrient delivery to the plants and proves their efficacy in terms of crop productivity and environmental sustainability over bulky chemical fertilizers. Plants can absorb NFs by foliage or roots depending upon the application methods and properties of the particles. NFs enhance the biotic and abiotic stresses tolerance in plants. It reduces the production cost and mitigates the environmental footprint. Multitude benefits of the NFs open new vistas towards sustainable agriculture and climate change mitigation. Although supra-optimal doses of NFs have a detrimental effect on crop growth, soil health, and environmental outcomes. The extensive release of NFs into the environment and food chain may pose a risk to human health, hence, need careful assessment. Thus, a thorough review on the role of different NFs and their impact on crop growth, productivity, soil, and environmental quality is required, which would be helpful for the research of sustainable agriculture.

Nanotechnology-enabled biofortification strategies for micronutrients enrichment of food crops: Current understanding and future scope

Nutrient deficiency in food crops severely compromises human health, particularly in under privileged communities. Globally, billions of people, particularly in developing nations, have limited access to nutritional supplements and fortified foods, subsequently suffering from micronutrient deficiency leading to a range of health issues. The green revolution enhanced crop production and provided food to billions of people but often falls short with respect to the nutritional quality of that food. Plants may assimilate nutrients from synthetic chemical fertilizers, but this approach generally has low nutrient delivery and use efficiency. Further, the overexposure of chemical fertilizers may increase the risk of neoplastic diseases, render food crops unfit for consumption and cause environmental degradation. Therefore, to address these challenges, more research is needed for sustainable crop yield and quality enhancement with minimum use of chemical fertilizers. Complex nutritional disorders and 'hidden hunger' can be addressed through biofortification of food crops. Nanotechnology may help to improve food quality via biofortification as plants may readily acquire nanoparticle-based nutrients. Nanofertilizers are target specific, possess controlled release, and can be retained for relatively long time periods, thus prevent leaching or run-off from soil. This review evaluates the recent literature on the development and use of nanofertilizers, their effects on the environment, and benefits to food quality. Further, the review highlights the potential of nanomaterials on plant genetics in biofortification, as well as issues of affordability, sustainability, and toxicity.

Comparative analysis of iron oxide nanoparticles synthesized from ginger (Zingiber officinale) and cumin seeds (Cuminum cyminum) to induce resistance in wheat against drought stress

In the present study, iron oxide nanoparticles (Fe3O2-NPs) synthesized from ginger (Zingiber officinale) and cumin seeds (Cuminum Cyminum L.) extracts were investigated to reveal their potential to enhance the growth and drought resistance of wheat plants under drought stress. In an In Vitro experiment, four different concentrations for Fe3O2-NPs (0.3 mM, 0.6 mM, 0.9 mM, and 1.2 mM) of ginger and cumin seeds were tested. Among all the concentrations tested, ginger Fe3O2-NPs (0.6 mM) and cumin seeds Fe3O2-NPs (1.2 mM) were more effective to enhance wheat germination, biomass, and survival percentage under drought stress and irrigated conditions than the non-treated control plant. In a pot experiment, wheat plants under induced water stress showed marked up-regulation in the biochemical resistance mechanisms when treated with ginger Fe3O2-NPs (0.6 mM) and cumin seeds Fe3O2-NPs (1.2 mM) than the non-treated control. Cumin seeds Fe3O2-NPs (1.2 mM) were more effective than ginger Fe3O2-NPs (0.6 mM) in ameliorating adverse effects of drought stress in wheat. Results demonstrated that cumin seeds Fe3O2-NPs (1.2 mM) exhibited a higher increase in chlorophyll a, b and carotenoids (72%, 265% and 96% respectively), proline (127%), superoxide dismutase (115%), peroxidase (43.8%), ascorbate peroxidase (44.6%). This also showed higher reduction in lipid peroxidation, electrolyte leakage and increased soluble sugars and total Fe content in the roots and shoots than non-treated plants under drought. Hence, nano-priming can be considered an effective strategy for sustainable food production in marginal soils.

Biofortification-A Frontier Novel Approach to Enrich Micronutrients in Field Crops to Encounter the Nutritional Security

Globally, many developing countries are facing silent epidemics of nutritional deficiencies in human beings and animals. The lack of diversity in diet, i.e., cereal-based crops deficient in mineral nutrients is an additional threat to nutritional quality. The present review accounts for the significance of biofortification as a process to enhance the productivity of crops and also an agricultural solution to address the issues of nutritional security. In this endeavor, different innovative and specific biofortification approaches have been discussed for nutrient enrichment of field crops including cereals, pulses, oilseeds and fodder crops. The agronomic approach increases the micronutrient density in crops with soil and foliar application of fertilizers including amendments. The biofortification through conventional breeding approach includes the selection of efficient genotypes, practicing crossing of plants with desirable nutritional traits without sacrificing agricultural and economic productivity. However, the transgenic/biotechnological approach involves the synthesis of transgenes for micronutrient re-translocation between tissues to enhance their bioavailability. Soil microorganisms enhance nutrient content in the rhizosphere through diverse mechanisms such as synthesis, mobilization, transformations and siderophore production which accumulate more minerals in plants. Different sources of micronutrients viz. mineral solutions, chelates and nanoparticles play a pivotal role in the process of biofortification as it regulates the absorption rates and mechanisms in plants. Apart from the quality parameters, biofortification also improved the crop yield to alleviate hidden hunger thus proving to be a sustainable and cost-effective approach. Thus, this review article conveys a message for researchers about the adequate potential of biofortification to increase crop productivity and nourish the crop with additional nutrient content to provide food security and nutritional quality to humans and livestock.

Hormetic effects of zinc on growth and antioxidant defense system of wheat plants

Although hormesis induced by heavy metals is a well-known phenomenon, the involved biological mechanisms are not fully understood. Zinc (Zn) is an essential micronutrient for wheat, an important crop contributing to food security as a main staple food; however, excessive Zn is detrimental to the growth of wheat. The aim of this study was to evaluate morphological and physiological responses of two wheat varieties exposed to a broad range of Zn concentrations (0-1000 μM) for 14 days. Hormesis was induced by Zn in both wheat varieties. Treatment with 10-100 μM Zn promoted biomass accumulation by enhancing the photosynthetic ability, the chlorophyll content and the activities of antioxidant enzymes. Increased root/shoot ratio suggested that shoot growth was severely inhibited when Zn concentration exceeded 300 μM by reducing photosynthetic ability and the content of photosynthetic pigments. Excessive Zn accumulation (Zn treatment of 300-1000 μM) in leaf and root induced membrane injuries through lipid peroxidation as malondialdehyde (MDA) content increased with increasing Zn concentration. The results show that MDA content was higher than other treatments by 16.1-151.1% and 15.0-88.3% (XN979) and 36.8-235.7% and 20.6-83.8% (BN207) in the leaves and roots under 1000 μM Zn treatment. To defend against Zn toxicity, ascorbate (AsA), glutathione (GSH), non-protein thiols (NPT) and phytochelatin (PC) content of both wheat varieties (except leaf GSH content of BN207) was increased, while, the activities of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and the content of soluble protein decreased by 300-1000 μM Zn. The results showed that AsA-GSH cycle and NPT and PC content of wheat seedlings play important roles in defending against Zn toxicity. This study contributes new insights into the physiological mechanisms underlying the hormetic response of wheat to Zn, which could be beneficial for optimizing plant health in changing environments and improving risk assessments.

Biosynthesis of Nano-Selenium and Its Impact on Germination of Wheat under Salt Stress for Sustainable Production

Selenium and its derivatives have been found capable of excellent biological responses. However, the element in its bulk form has low bioavailability and increased toxicity, meaning the production of effective forms with sustainable methods has become urgent. Several microorganisms, including fungi, bacteria and yeast, as well as higher plants, are capable of biosynthesizing nanoparticles such as nano-selenium (nano-Se), which has wide applications in medicine, agriculture and industry. Thus, the biosynthesis of nano-Se using some bacterial species was the main target of this study. The production of nano-Se and the monitoring of its impact on the wheat germination of seeds under salt stress (i.e., 50, 100, and 150 mM NaCl) was also evaluated in the current study. The ameliorative role of nano-Se doses (i.e., 50, 75, and 100 mg L−1) in the germination of wheat seeds under salt stress was also investigated. Based on sodium selenite tolerance and reducing selenite to elemental Se-NPs, the most effective isolate (TAH) was selected for identification using the 16S rRNA gene sequence, which belonged to Bacillus cereus TAH. The final germination percent, mean germination time, vigor index and germination rate index were improved by 25, 25, 39.4 and 11%, respectively, under 15 mM sodium chloride concentration when 100 mg L−1 nano-selenium was used. On the other hand, the results obtained from a gnotobiotic sand system reveal that with treatment with 100 mg L−1 nano-selenium under high Ec values of 14 ds m−1, the vegetative growth parameters of shoot length, root length, fresh weight and dry weight were improved by 22.8, 24.9, 19.2 and 20%, respectively, over untreated controls. The data obtained from this study reveal that the use of nano-selenium produced by Bacillus cereus offers improved wheat seed germination under a salt-affected environment.

Foliar application of zinc oxide nanoparticles: An effective strategy to mitigate drought stress in cucumber seedling by modulating antioxidant defense system and osmolytes accumulation

Drought is a major environmental threat that affects plant growth and productivity. Strategies to mitigate the detrimental impacts of drought stress on plants are under scrutiny. Nanotechnology is considered an effective tool in resolving a wide range of environmental issues by offering novel and pragmatic solutions. A pot experiment was performed to determine the efficacy of zinc oxide nanoparticles (ZnO NPs) as a foliar application (25 mg L^-1 and 100 mg L^-1) on the growth performance of cucumber subjected to drought stress. Applied ZnO NPs under normal conditions resulted in significant growth and biomass enhancement while reducing drought-induced decline. Photosynthetic pigments, photosynthesis, and PSII activity enhanced due to ZnO NPs application, attaining maximal values at 100 mg L^-1 of ZnO NPs. Drought stress restricted growth and biomass buildup in cucumber seedlings by stimulating oxidative stress, which was manifested to excessive buildup of reactive oxygen species (ROS) and peroxidation, thereby decreasing membrane functioning. Plants exposed to ZnO NPs exhibited a reduction in ROS accumulation and lipid peroxidation. The substantial reduction in oxidative damage was manifested with the enhancement of enzymatic and non-enzymatic antioxidant components. The phenol and mineral contents were reduced due to drought stress. In addition, the content of proline, glycine betaine, free amino acids, and sugars increased due to ZnO NPs under normal and drought conditions. Furthermore, the drought-induced decline in the content of phenol and mineral nutrients was mitigated by ZnO NPs foliar application. These findings reveal that exogenous ZnO NPs application may be a pragmatic option in dealing with the drought stress of cucumber seedlings.

A comprehensive analysis on source-distribution-bioaccumulation-exposure risk of metal(loid)s in various vegetables in peri-urban areas of Shenzhen, China

The health risk induced by metal(loid)s in crops are becoming increasingly serious. In this study, eight major vegetables and rhizosphere soils were collected in a peri-urban area with intense electronic information manufacturing activities. The source, distribution and bioaccumulation of six typical metal(loid)s in different vegetable species were analyzed, and exposure risk through vegetable ingestion was estimated. Results showed that vegetables and agricultural soils in the study area suffered from serious metal(loid)s pollution, especially for Cd and Pb. The bioaccumulation capacity differed greatly among individual metal(loid)s and vegetable categories. In general, the highest transfer factors (TF) for Cd, Pb, and As were found in leafy vegetables, while leguminous vegetables had the highest TF of Cu and Zn and root vegetables had the highest TF for Cr. Significant correlations were found between concentrations in vegetables and rhizosphere soils for most metal(loid)s, the exceptions being Pb and Zn. The enrichment of Pb, Cd, Cr and As was mainly attributed to electronic information manufacturing activities, while the enrichment of Zn, Cu and Cd was associated with the application of commercial fertilizers and pesticides. The health risk associated with vegetable intake decreased in the order of leafy > fruit > leguminous > root vegetables. Leafy vegetables were identified as the category with the highest risk, with the mean risk value of 1.26. Cd was the major risk element for leafy vegetables. The non-carcinogenic risks estimated for leguminous and root vegetables were under the acceptable level. In conclusion, special attention should be paid to the health risks of toxic metal(loid)s in leafy vegetables in peri-urban areas with intense electronic information manufacturing activities. In order to minimize health risk, it is necessary to identify low-risk crops based on a comprehensive consideration of the metal(loid)s' pollution characteristics, transfer factors and local people's consumption behaviors.

Biofertilizers and nanofertilizers for sustainable agriculture: Phycoprospects and challenges

Increased food demands and ceasing nutrient deposits have resulted in a great shortfall between the food supply and demand and would be worse in the years to come. Higher inputs of synthetic fertilizers on lands have resulted in environmental pollution, persistent changes in the soil ecology, and physicochemical conditions. This has greatly decreased the natural soil fertility thereby hindering agricultural productivity, human health, and hygiene. Bio-based resilient nutrient sources as wastewater-derived algae are promising as a complete nutrient for agriculture and have the potential to be used in soilless cultivations. Innovations in nano-fortification and nano-sizing of minerals and algae have the potential to facilitate nutrients bioavailability and efficacy for a multifold increase in productivity. In this context, various options on minerals nanofertilizer application in agricultural food production besides efficient biofertilizer have been investigated. Algal biofertilizer with the nanoscale application has huge prospects for further agriculture productivities and fosters suitable development.

Mulberry based zinc nano-particles mitigate salinity induced toxic effects and improve the grain yield and zinc bio-fortification of wheat by improving antioxidant activities, photosynthetic performance, and accumulation of osmolytes and hormones

Salinity stress (SS) is a challenging abiotic stress that limits crop growth and productivity. Sustainable and cost effective methods are needed to improve crop production and decrease the deleterious impacts of SS. Zinc (Zn) nano-particles (NPs) have emerged as an important approach to regulating plant tolerance against SS. However, the mechanisms of SS tolerance mediated by Zn-NPs are not fully explained. Thus, this study was performed to explore the role of Zn-NPs (seed priming and foliar spray) in reducing the deleterious impacts of SS on wheat plants. The study comprised different SS levels: control, 6 and 12 dS m^-1, and different Zn-NPs treatments: control, seed priming (40 ppm), foliar spray (20 ppm), and their combination. Salinity stress markedly reduced plant growth, biomass, and grain yield. This was associated with enhanced electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H₂O₂), sodium (Na), chloride (Cl) accumulation, reduced photosynthetic pigments, relative water contents (RWC), photosynthetic rate (Pn), transpiration rate (Tr), stomata conductance (Gs), water use efficiency (WUE), free amino acids (FAA), total soluble protein (TSP), indole acetic acid (IAA), gibberellic acid (GA), and nutrients (Ca, Mg, K, N, and P). However, the application of Zn-NPs significantly improved the yield of the wheat crop, which was associated with reduced abscisic acid (ABA), MDA, H₂O₂ concentration, and EL, owing to improved antioxidant activities, and an increase in RWC, Pn, Tr, WUE, and the accumulation of osmoregulating compounds (proline, soluble sugars, TSP, and FAA) and hormones (GA and IAA). Furthermore, Zn-NPs contrasted the salinity-induced uptake of toxic ions (Na and Cl) and increased the uptake of Ca, K, Mg, N, and P. Additionally, Zn-NPs application substantially increased the wheat grain Zn bio-fortification. Our results support previous findings on the role of Zn-NPs in wheat growth, yield, and grain Zn bio-fortification, demonstrating that beneficial effects are obtained under normal as well as adverse conditions, thanks to improved physiological activity and the accumulation of useful compounds. This sets the premise for general use of Zn-NPs in wheat, to which aim more experimental evidence is intensively being sought. Further studies are needed at the genomic, transcriptomic, proteomic, and metabolomic level to better acknowledge the mechanisms of general physiological enhancement observed with Zn-NPs application.

Interaction of zinc oxide nanoparticles with soil: Insights into the chemical and biological properties

Widespread use of zinc oxide nanoparticles (ZnO-NPs) threatens soil, plants, terrestrial and aquatic animals. Thus, it is essential to explore the fate and behavior of NPs in soil and also its mechanism of interaction with soil microbial biodiversity to maintain soil health and quality to accomplish essential ecosystem services. With this background, the model experiment was conducted in the greenhouse to study the impact of ZnO-NPs on soil taking maize as a test crop. The X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy and Particles size analysis of engineered NPs confirmed that the material was ZnO-NPs (particle size--65.82 nm). The application of ZnO-NPs resulted in a significant decrease in soil pH. Significantly high EC (0.13 dS m^-1) was recorded where ZnO-NPs were applied at the rate of 2.5 mg Zn kg^-1 soil over control (0.12 dS m^-1). A significant increase in soil available phosphorus was observed on applying ZnO-NPs (15.29 mg kg^-1 of soil) as compared to control (11.84 mg kg^-1 of soil). Maximum soil available Zn (2.09 mg kg^-1) was recorded in ZnO-NPs-amended soil (T₁₁) which was significantly higher than control (0.33 mg kg^-1) as well as treatments containing conventional zincatic fertilizers. The inhibition rates of dehydrogenase enzyme activity in the presence of 0.5 mg, 1.25 mg and 2.5 mg ZnO-NPs per kg soil were 31.3, 46.2 and 49.7%, respectively. Soil microbial biomass carbon was significantly reduced (103.33 µg g^-1 soil) in soils treated with ZnO-NPs over control (111.33 µg g^-1 soil). Soil bacterial count was also significantly lesser (12.33 × 10⁵ CFU) in the case where 2.5 mg kg^-1 ZnO-NPs were applied as compared to control (21.33 × 10⁵ CFU). The corresponding decrease in fungal and actinomycetes colony count was 24.16, 37.35, 46.15% and 14.59, 17.97, 22.45% with the application of 0.5 mg, 1.25 mg and 2.5 mg ZnO-NPs per kg soil, respectively, as compared to control. Thus, the use of ZnO-NPs resulted in an increase in soil available Zn but inhibited soil microbial activity.

Effect of ZnO Nanoparticles on Growth and Biochemical Responses of Wheat and Maize

Zinc is an essential element that is also renowned for widespread contamination and toxicity at high concentrations. The present study was carried out to analyze the responses induced by lower, as well as higher, doses of zinc (0-200 mg/L), in the form of zinc oxide nanoparticles (ZnO NPs) in wheat and maize, for a period of 21 days. Accumulation of zinc increases with increasing Zn doses in both wheat and maize, with higher doses being in wheat (121 mg/kg in root and 66 mg/kg in shoot) than in maize (95 mg/kg in root and 48 mg/kg in shoot). The activity of alpha-amylase showed increase, while that of dehydrogenase decline, in response to ZnO NPs. The length and biomass of plants and photosynthetic pigments increased slightly upon ZnO NPs supply. Malondialdehyde content showed a progressive increase in root and shoot of both plants. However, in response, antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase) showed increase up to lower concentrations (100 mg/L) of ZnO NPs but decline variably at higher levels (150-200 mg/L) in wheat and maize. The results suggest that lower supply of ZnO NPs (100 mg/L) could be stimulatory to the growth of plants and can be recommended as a Zn fertilizer source for crop production.

Interaction of different-sized ZnO nanoparticles with maize (Zea mays): Accumulation, biotransformation and phytotoxicity

This study aimed to investigate the biotransformation of ZnO nanoparticles (NPs) in maize grown in hydroponics for ecotoxicity assessment. Maize seedlings grown for 14 days were exposed to a solution of 9 nm ZnO NPs, 40 nm ZnO NPs, and ZnSO₄ at a Zn concentration of 300 mg L^-1 for 1, 3, and 7 days, respectively. The results of in-situ Zn distribution in maize (Zea mays) showed that 9 nm ZnO NPs could quickly enter the roots of maize and reach the center column transport system of the stem. The results of transmission electron microscopy combined with energy dispersive X-ray spectroscopy revealed that ZnO NPs were accumulated in the vacuoles of the roots, and then transformed and transported through vesicles. Simulated studies showed that low pH (5.6) played a critical role in the transformation of ZnO NPs, and organic acids (K_f = 10^11.4) could promote particle dissolution. Visual MINTEQ software simulated the species of Zn after the entry of ZnO NPs or Zn²⁺ into plants and found that the species of Zn was mainly Zn²⁺ when the Zn content of plants reached 200-300 ppm. Considering that the lowest Zn content of the roots in treatments was 1920 mg kg^-1, combination of the result analysis of root effects showed that the toxicity of roots in most treatments had a direct relationship with Zn²⁺. However, treatment with 9 nm ZnO NPs exhibited significantly higher toxicity than ZnSO₄ treatment on day 1 when the Zn²⁺ concentration difference was not significant, which was mainly due to the large amount of ZnO NPs deposited in the roots. To the authors' knowledge, this study was the first to confirm the process of biotransformation and explore the factors affecting the toxicity of ZnO NPs in depth.

Foliar Sprayed Green Zinc Oxide Nanoparticles Mitigate Drought-Induced Oxidative Stress in Tomato

This study explored the effectiveness of green zinc oxide nanoparticles (ZnO-NPs) foliar spray on tomato growth and oxidative stress relief under drought conditions. Tomato plant subjected to four water regimes (100, 75, 50, and 25% FC), and in the same while seedlings were sprayed with 25, 50, and 100 mg/L green ZnO-NPs. The results showed that tomato growth parameters reduced significantly by increasing drought stress levels, while ZnO-NPs enhanced plant growth under all studied drought levels. Out of three ZnO-NPs concentrations tested, 25 and 50 mg/L ZnO-NPs proved to be the optimum treatments for alleviating drought stress. They increased shoot and root biomass compared to untreated controls. Application of 25 and 50 mg/L ZnO-NPs enhanced shoot dry weight by about 2-2.5-fold, respectively, under severe drought conditions (25%) compared to ZnO-NPs untreated plants. The application of 25 and 50 mg/L green ZnO-NPs decreased the drought-induced oxidative stress as indicated by the reduction in malondialdehyde and hydrogen peroxide concentrations compared to untreated controls. While 100 mg/L ZnO-NPs further increased oxidative stress. The beneficial effects of ZnO-NPs were evident in the plants' defensive state, in which the concentration of ascorbic acid, free phenols, and the activity of superoxide dismutase, catalase, and ascorbate peroxidase were maintained at higher levels compared to NPs-untreated plants. At severe drought conditions, 25 mg/L ZnO-NPs induced SOD, CAT, and APX activity by about 3.99-, 3.23-, and 2.82-fold of their corresponding controls, respectively. Likewise, at 25% FC, SOD, CAT, and APX activity increased with 50 mg/L ZnO-NPs by about 4.58-, 3.57-, and 3.25-fold consecutively compared with their respective controls. Therefore, foliar use of green ZnO-NPs at lower concentrations might be suggested as an efficient way for enhancing tomato tolerance to drought stress.

Insight into the Prospects for Nanotechnology in Wheat Biofortification

Simple Summary

Wheat is a major crop consumed by a large population of the world. Hence, increasing its nutritional value can largely handle the malnutrition issues of the growing population. In the past few decades, different biofortification techniques including conventional breeding, transgenic approach, and agronomic biofortification have been largely employed for increasing the nutrient content in wheat grains. However, all of these techniques have their own drawbacks such as environmental hazards, long time requirement, reduced acceptability etc. Thus, nanobiofortification of wheat crop has gained interest as an efficient alternative strategy to achieve nutritional gains. However, there is still a long way forward to effectively utilize nanotechnology for wheat nutritional development. In this scenario, a review on the current advancement in wheat nanobiofortification is highly required so that the lacking points in this research area can be identified and accomplished. However, such a review article has been missing so far. This review describes the progress in the use of nanomaterials for wheat biofortification till date. It will help the scientific community to identify the lack in this research area and widely implement the nanotechnology to biofortify wheat crops.

Abstract

The deficiency of nutrients in food crops is a major issue affecting the health of human beings, mainly in underdeveloped areas. Despite the development in the methods of food fortification, several barriers such as lack of proper regulations and smaller public-private partnerships hinder its successful implementation in society. Consequently, genetic and agronomic biofortification has been suggested as the potential techniques for fortifying the nutrients in diets. However, the time-consuming nature and restricted available diversity in the targeted crop gene pool limit the benefits of genetic biofortification. In agronomic biofortification, organic fertilizers face the problem of prolonged duration of nutrients release and lesser content of minerals; while in inorganic fertilizers, the large-sized fertilizers (greater than 100 nm) suffer from volatilization and leaching losses. The application of nanotechnology in agriculture holds enormous potential to cope with these challenges. The utility of nanomaterials for wheat biofortification gains its importance by supplying the appropriate dose of fertilizer at the appropriate time diminishing the environmental concerns and smoothening the process of nutrient uptake and absorption. Wheat is a major crop whose nano-biofortification can largely handle the issue of malnutrition and nutrients deficiency in human beings. Though several research experiments have been conducted at small levels to see the effects of nano-biofortification on wheat plants, a review article providing an overview of such studies and summarizing the benefits and outcomes of wheat nano-biofortification is still lacking. Although a number of review articles are available on the role of nanotechnology in wheat crop, these are mostly focused on the role of nanoparticles in alleviating biotic and abiotic stress conditions in wheat. None of them focused on the prospects of nanotechnology for wheat biofortification. Hence, in this review for the first time, the current advancement in the employment of different nanotechnology-based approaches for wheat biofortification has been outlined. Different strategies including the supply of nano-based macro- and micronutrients that have shown promising results for wheat improvement have been discussed in detail. Understanding several aspects related to the safe usage of nanomaterials and their future perspectives may enhance their successful utilization in terms of economy and fulfillment of nutritional requirements following wheat nano-biofortification.

The role of halophytic nanoparticles towards the remediation of degraded and saline agricultural lands

Salinity is one of the major causes of abiotic stress that leads to a reduction in crop yield. One strategy to alleviate and improve crop yield is to use halophytes. These types of plants naturally produce bioactive secondary metabolites, proteins, carbohydrates, and biopolymers that are involved in specialized physiological adaptation mechanisms to alleviate soil salinity. These traits could be leveraged and, in turn, be the focus of future breeding programs aimed to improve salinity resistance in traditional crops. Recently, the field of nanotechnology has gained the attention of researchers involved in agricultural science and associated disciplines. However, information on salinity tolerance mechanisms of halophytes, based on nanoparticles in agricultural crop plants, is limited. Recently, the use of selected halophytic-based nanoparticles has shown to improve crop performance by enhancing the plants' ion flux, improving water efficiency, root hydraulic movement in the favor of plant photosynthesis, the production of proteins involved in oxidation-reduction reactions, reactive oxygen species (ROS) detoxification, and hormonal signaling pathways under stress. Therefore, the aim of this review is to highlight the application of halophytic nanoparticles in alleviating salt stress in plants by understanding the mechanisms of plant growth, water relation, ion flux, photosynthesis, and the antioxidant defense system. This review also addresses uncertainties, ecotoxicological concerns, and associated drawbacks of nanoparticles on the environment. Future research perspectives with respect to the sustainable usage of nanoparticles in saline agriculture have also been presented.

Nanobiotechnological advancements in agriculture and food industry: Applications, nanotoxicity, and future perspectives

The high demand for sufficient and safe food, and continuous damage of environment by conventional agriculture are major challenges facing the globe. The necessity of smart alternatives and more sustainable practices in food production is crucial to confront the steady increase in human population and careless depletion of global resources. Nanotechnology implementation in agriculture offers smart delivery systems of nutrients, pesticides, and genetic materials for enhanced soil fertility and protection, along with improved traits for better stress tolerance. Additionally, nano-based sensors are the ideal approach towards precision farming for monitoring all factors that impact on agricultural productivity. Furthermore, nanotechnology can play a significant role in post-harvest food processing and packaging to reduce food contamination and wastage. In this review, nanotechnology applications in the agriculture and food sector are reviewed. Implementations of nanotechnology in agriculture have included nano- remediation of wastewater for land irrigation, nanofertilizers, nanopesticides, and nanosensors, while the beneficial effects of nanomaterials (NMs) in promoting genetic traits, germination, and stress tolerance of plants are discussed. Furthermore, the article highlights the efficiency of nanoparticles (NPs) and nanozymes in food processing and packaging. To this end, the potential risks and impacts of NMs on soil, plants, and human tissues and organs are emphasized in order to unravel the complex bio-nano interactions. Finally, the strengths, weaknesses, opportunities, and threats of nanotechnology are evaluated and discussed to provide a broad and clear view of the nanotechnology potentials, as well as future directions for nano-based agri-food applications towards sustainability.

Effects of Soil pH and Coatings on the Efficacy of Polymer coated ZnO Nanoparticulate fertilizers in Wheat (Triticum aestivum)

This study used ZnO nanoparticles (NPs) as seed treatments and as soil amendments to enhance Zn concentrations in wheat grain. In the seed treatment experiment, seeds were treated with dextran coated (DEX-ZnO) and bare ZnO NP suspensions, in addition to ZnSO₄, at 500 mg Zn/L. In the soil amendment experiment, soil pH was adjusted to 6 and 8, then soils were spiked with 15 mg Zn/kg soil in the form of DEX-ZnO and bare ZnO NPs, as well as ZnSO₄. For the seed treatment, ZnO NPs resulted in significantly higher grain Zn concentration 96.9 ± 25.4 compared to (72.2 ± 25.4), (78.3 ± 24.3), and (81.0 ± 19.4) mg Zn/kg in the control, ZnSO₄, and DEX-ZnO NPs treatments, respectively. In the soil amendment experiment, grain Zn concentrations were the same across all Zn treatments regardless of soil pH. Plants grown at pH 6 had higher Zn accumulation and leaf and stem biomass compared to pH 8. This study demonstrates that treatment of seeds with ZnO NPs can enhance Zn content of grain using far less Zn than is typically used for soil amendments. This may help reduce the environmental impact of Zn fertilization.

Nano-biofortification of different crops to immune against COVID-19: A review

Human health and its improvement are the main target of several studies related to medical, agricultural and industrial sciences. The human health is the primary conclusion of many studies. The improving of human health may include supplying the people with enough and safe nutrients against malnutrition to fight against multiple diseases like COVID-19. Biofortification is a process by which the edible plants can be enriched with essential nutrients for human health against malnutrition. After the great success of biofortification approach in the human struggle against malnutrition, a new biotechnological tool in enriching the crops with essential nutrients in the form of nanoparticles to supplement human diet with balanced diet is called nano-biofortification. Nano biofortification can be achieved by applying the nano particles of essential nutrients (e.g., Cu, Fe, Se and Zn) foliar or their nano-fertilizers in soils or waters. Not all essential nutrients for human nutrition can be biofortified in the nano-form using all edible plants but there are several obstacles prevent this approach. These stumbling blocks are increased due to COVID-19 and its problems including the global trade, global breakdown between countries, and global crisis of food production. The main target of this review was to evaluate the nano-biofortification process and its using against malnutrition as a new approach in the era of COVID-19. This review also opens many questions, which are needed to be answered like is nano-biofortification a promising solution against malnutrition? Is COVID-19 will increase the global crisis of malnutrition? What is the best method of applied nano-nutrients to achieve nano-biofortification? What are the challenges of nano-biofortification during and post of the COVID-19?

Effect of ZnO nanoparticles on the productivity, Zn biofortification, and nutritional quality of rice in a life cycle study

Zinc oxide nanoparticles (ZnO NPs), have been commonly used in agriculture, and have attracted more attention for researchers. In this study, a 2-year experiment was conducted involving two Zn types (ZnO NPs and ZnSO₄), two concentrations of Zn (25 and 100 mg kg^-1), and three Zn application stages (basal stage, tillering stage, and panicle stage). This study comprehensively evaluated the effects of ZnO NPs on rice yield, nutrient uptake, Zn biofortification and grain nutritional quality. Our results showed that both ZnO NPs and Zn salt increased grain yield, NPK uptake, and grain Zn concentration. ZnO NPs application enhanced NPK content in rice, with subsequence increasing panicle number (3.8-10.3%), spikelet number per panicle (2.2-4.7%), and total biomass (6.8-7.6%), thereby promoting the rice yield. Compared with conventional fertilization, ZnO NPs enhanced Zn concentration of brown rice by 13.5-39.4%, this had no negative impact on human health. ZnO NPs application at panicle stage have a higher effectiveness in improving Zn concentration of brown rice than at basal and tillering stage. Furthermore, the application of ZnO NPs at panicle stage was more efficient in increasing Zn concentration of brown rice than for Zn salt. ZnO NPs application slightly altered the amino acids content of rice grains, but had no significant impact on total amino acids content. This study highlights that ZnO NPs could be used as a high performance and safe Zn fertilizer in rice production ecosystem.

Carbon sphere-zinc sulphate nanohybrids for smart delivery of zinc in rice (Oryza sativa L)

The laboratory research was attempted to find nano zinc fertilizer utilizing the carbon sphere as a substrate. Typically the encapsulation techniques are followed in the drug delivery system, the limited work was done in nano-based zinc micronutrient for slow release of nutrients to crop. The use efficiency of zinc micronutrients in the soil is only less than 6 percentage. In universal, the deficiency of zinc micronutrients causes malnutrition problems in human beings, especially in children. After considering this problem we planned to prepare zinc nano fertilizer by using the carbon sphere for need-based slow release and increase the use efficiency of zinc micronutrient in soil. In this study we synthesis the carbon sphere nanoparticle after the formation of carbon sphere the zinc sulphate was loaded and characterized by utilizing Scanning Electron Microscopy, Surface Area and Porosity, X-ray diffraction analysis, Fourier Transform Infrared Spectroscopy, Transmission Electron Microscopy. The research result shows that the nano carbon sphere was excellently loaded with zinc sulphate to the tune of 8 percentage and it was confirmed by Energy dispersive X-beam spectroscopy. The zinc loaded carbon sphere release nutrient for a prolonged period of up to 600 h in the case of conventional zinc sulphate zinc release halted after 216 h in percolation reactor studies. The zinc nano fertilizer is recommended in agriculture to increase zinc use efficiency, crop yield without any environmental risk.

Zinc oxide nanoparticles and 24-epibrassinolide alleviates Cu toxicity in tomato by regulating ROS scavenging, stomatal movement and photosynthesis

Nanoparticles (NPs) have recently emerged as potential agents for plants to ameliorate abiotic stresses by acting as nano-fertilizers. In this regard, the influence of the zinc oxide nanoparticles (ZnO-NPs) on plant responses to copper (Cu) stress has been poorly understood. Hence, the present study was executed to explore the role of ZnO-NPs (foliar) and 24-epibrassinolide (EBL; root dipping) individually or in combined form in the resilience of tomato (Solanum lycopersicum) plant to Cu stress. Tomato seeds were sown to make the nursery; and at 20 days after sowing (DAS) the plantlets were submerged in 10-8 M of EBL solution for 2 h, and subsequently transplanted in the soil-filled earthen pots. Cu concentration (100 mg kg-1) was applied to the soil at 30 DAS, whereas at 35 DAS plants were sprinkled with double distilled water (DDW; control), 50 mg/L of Zinc (Zn) and 50 mg/L of ZnO-NPs; and plant performance were evaluated at 45 DAS. It was evident that Cu-stress reduced photosynthesis (17.3%), stomatal conductance (18.1%), plant height (19.7%), and nitrate reductase (NR) activity (19.2%), but increased malondialdehyde (MDA; 29.4%), superoxide radical (O2-; 22.3%) and hydrogen peroxide (H2O2; 26.2%) content in S. lycopersicum. Moreover, ZnO-NPs and/or EBL implemented via different modes improved photosynthetic activity, stomatal aperture, growth, cell viability and activity of antioxidant enzymes and proline that augmented resilience of tomato plants to Cu stress. These observations depicted that application of ZnO-NPs and EBL could be a useful approach to assist Cu confiscation and stress tolerance against Cu in tomato plants grown in Cu contaminated sites.

Delineating the future of iron biofortification studies in rice: challenges and future perspectives

Iron (Fe) deficiency in humans is a widespread problem worldwide. Fe biofortification of rice (Oryza sativa) is a promising approach to address human Fe deficiency. Since its conceptualization, various biofortification strategies have been developed, some of which have resulted in significant increases in grain Fe concentration. However, there are still many aspects that have not yet been addressed in the studies to date. In this review, we first overview the important rice Fe biofortification strategies reported to date and the complications associated with them. Next, we highlight the key outstanding questions and hypotheses related to rice Fe biofortification. Finally, we make suggestions for the direction of future rice biofortification studies.

Effects of metal nanoparticle-mediated treatment on seed quality parameters of different crops

The increasing population of the world requires novel techniques to feed everyone, which can replace or work along with traditional methods to increase production of agricultural crops. In recent times, nanotechnology is considered as a promising and emerging approach to be incorporated in agriculture to improve productivity of different crops by the administration of nanoparticles through seed treatment, foliar spray on plants, nano-fertilizers for balanced crop nutrition, nano-herbicides for effective weed control, nanoinsecticides for plant protection, early detection of plant diseases and nutrient deficiencies using diagnostics kits, and nano-pheromones for effective monitoring of pests. Further, distinct nanoparticles with unique physicochemical and biological properties are used in agriculture to increase the percentage of seed germination, which is the initial step to increase the crop yield. In the context of agricultural crops, nanoparticles have both positive effects on seed quality parameters, such as germination percentage, seedling length, seedling dry weight and vigor indices, as well as negative impacts of causing toxicity toward the environment. Thus, the aim of this review article is to provide a comprehensive overview on the effects of super-dispersive metal powders, such as zinc, silver, and titanium nanoparticles on the seed quality parameters of different crops. In addition, the drawback of conventional seed growth enhancers, impact of metal nanoparticles toward seeds, and mechanism of nanoparticles to increase seed germination were also discussed.

Zinc regulates the hydraulic response of maize root under water stress conditions

Zinc (Zn) is involved in plant growth and stress resistance and is known to increase crop yield. Here, we investigated the effect of Zn on water absorption in the roots of maize (Zea mays L.), a crop which is sensitive to Zn deficiency, during water stress conditions. Seedlings of the maize variety "Zhengdan 958" were cultivated with 0.1 or 6 μM ZnSO₄·7H₂O. To simulate drought stress, three-week-old seedlings were exposed to 15% polyethylene glycol (PEG). Root growth parameters, root antioxidant enzyme activity, root hydraulic conductivity, root aquaporin gene expression, root and leaf anatomy structure, leaf water potential, chlorophyll content, leaf area, and gas exchange parameters were measured. Under water stress, moderate Zn treatment promoted root growth; maintained root and leaf anatomy structural integrity. Moderate Zn significantly increased roots hydraulic conductivity (51%) and decreased roots antioxidant enzyme activity (POD: -11.1%, CAT: -35.1%, SOD: -3.1%) compared with low-level Zn under water stress. The expression of ZmPIP1;1, ZmPIP1;2, and ZmPIP2;2 was significantly higher with moderate Zn treatment than that of low-level Zn treatment. The leaf water potential, chlorophyll content, leaf area, and gas exchange parameters with moderate Zn treatment increased significantly under water stress compared with low-level Zn treatment. The moderate concentration of Zn improved root hydraulic conductivity in maize and increased resistance to simulated drought conditions by maintaining root structural integrity, decreasing antioxidant enzyme activity, and increasing aquaporin gene expression. Moderate Zn application increased root water absorption and leaf transpiration, thereby maintaining maize water balance under water stress conditions.

Efficacy of nanoparticles as nanofertilizer production: a review

Owing to the ever-increasing demand for food, the growing global population has forced farmers to increase fertilizer use. The overall use of fertilizers increased by 13 times between 1950 and 2020, from 15 to 194 million tons. Due to the resource shortages of chemical fertilizers on the market, agricultural costs are rising drastically every day because they cause an adverse impact on the environment by releasing chemical particulates and run-off agriculture. Biofertilizers have thus become a safer supplement to increase crop production without doing any harm to the environment, as they are produced industrially from a selected community of microorganisms that either develop a mutually beneficial relationship with plants or are part of their rhizosphere. They still have some drawbacks, which led to the development of a new avenue for the application of nanotechnology-mediated nanofertilizers. Nanotechnology recommends significant prospects for tailoring nanofertilizer production. They are typically coated with desired chemical composition having controlled release and targeted delivery of effective nanoscale ingredients, ability to improve plant productivity and to minimize environmental pollutants. The present review focuses primarily on the usefulness of nanofertilizers, as well as its environmental and safety concerns. The research would also include useful knowledge related to the introduction of different forms of nanoparticles within the agricultural field, contributing to the opening of a new route to nanorevolution.

Nano-Fertilization as an Emerging Fertilization Technique: Why Can Modern Agriculture Benefit from Its Use?

There is a need for a more innovative fertilizer approach that can increase the productivity of agricultural systems and be more environmentally friendly than synthetic fertilizers. In this article, we reviewed the recent development and potential benefits derived from the use of nanofertilizers (NFs) in modern agriculture. NFs have the potential to promote sustainable agriculture and increase overall crop productivity, mainly by increasing the nutrient use efficiency (NUE) of field and greenhouse crops. NFs can release their nutrients at a slow and steady pace, either when applied alone or in combination with synthetic or organic fertilizers. They can release their nutrients in 40–50 days, while synthetic fertilizers do the same in 4–10 days. Moreover, NFs can increase the tolerance of plants against biotic and abiotic stresses. Here, the advantages of NFs over synthetic fertilizers, as well as the different types of macro and micro NFs, are discussed in detail. Furthermore, the application of NFs in smart sustainable agriculture and the role of NFs in the mitigation of biotic and abiotic stress on plants is presented. Though NF applications may have many benefits for sustainable agriculture, there are some concerns related to the release of nanoparticles (NPs) from NFs into the environment, with the subsequent detrimental effects that this could have on both human and animal health. Future research should explore green synthesized and biosynthesized NFs, their safe use, bioavailability, and toxicity concerns.

Zinc from foliar-applied nanoparticle fertiliser is translocated to wheat grain: A 65Zn radiolabelled translocation study comparing conventional and novel foliar fertilisers

Foliar zinc (Zn) fertilisers can be used to supplement or replace soil applications of Zn in situations where soil properties may decrease the plant bioavailability of Zn. However, conventional foliar Zn formulations such as zinc sulfate can cause leaf damage due to the rapid release of high amounts of Zn²⁺ into leaf tissue which can be locally phytotoxic. Zinc oxide nanoparticles (ZnO-NPs) offer an alternative approach by providing a more sustained release of Zn into leaf tissue, and potentially avoiding the need for multiple applications. We compared the efficacy of ZnO-NPs and microparticles (ZnO-MPs) to that of conventional formulations (ZnCl₂ and ZnEDTA) in wheat. This is the first study to use ⁶⁵Zn radiolabelled formulations and gamma spectrometry to determine the translocation of Zn to the grains and subsequent efficiency of foliar-applied ZnO-NP fertilisers. We found that ZnEDTA was the most efficient fertiliser in terms of the proportion of applied Zn translocated to wheat grain. We also investigated the effect of Zn application rate on fertiliser efficiency. For all forms of Zn, when plants were treated with Zn at 750 mg/L or 75 mg/L, there were no significant differences in the concentration of applied Zn translocated to the grain. This suggests that current Zn application rates could be decreased while still maintaining the nutritional quality of grain. Finally, using photo-stimulated luminescence (PSL) autoradiography and synchrotron-based X-ray fluorescence microscopy (XFM) we showed that the grain distribution of foliar-applied Zn mirrors that of Zn derived from root uptake.

Potential of Using Ginger Essential Oils-Based Nanotechnology to Control Tropical Plant Diseases

Essential oils (EOs) have gained a renewed interest in many disciplines such as plant disease control and medicine. This review discusses the components of ginger EOs, their mode of action, and their potential nanotechnology applications in controlling tropical plant diseases. Gas chromatography-mass spectroscopy (GC-MS), high-performance liquid chromatography, and headspace procedures are commonly used to detect and profile their chemical compositions EOs in ginger. The ginger EOs are composed of monoterpenes (transcaryophyllene, camphene, geranial, eucalyptol, and neral) and sesquiterpene hydrocarbons (α-zingiberene, ar-curcumene, β-bisabolene, and β-sesquiphellandrene). GC-MS analysis of the EOs revealed many compounds but few compounds were revealed using the headspace approach. The EOs have a wide range of activities against many phytopathogens. EOs mode of action affects both the pathogen cell's external envelope and internal structures. The problems associated with solubility and stability of EOs had prompted the use nanotechnology such as nanoemulsions. The use of nanoemulsion to increase efficiency and supply of EOs to control plant diseases control was discussed in this present paper. The findings of this review paper may accelerate the effective use of ginger EOs in controlling tropical plant diseases.

Zinc oxide nanoparticles (ZnONPs) as a novel nanofertilizer: Influence on seed yield and antioxidant defense system in soil grown soybean (Glycine max cv. Kowsar)

Dearth of knowledge about the prospect of using Zinc (Zn) based nanoparticles (NPs) to enrich Zn-deficient soils with Zn warrants investigations into potential soil applications of ZnONPs for improving crop yield and plant health. Herein, we investigated the potential influence of ZnONPs on seed yield, focusing on particle size-, morphology-, and concentration-dependent responses of multiple antioxidant defense biomarkers, in soil-grown soybean (Glycine max cv. Kowsar) during its lifecycle of 120 d. We achieved this goal following a rational design strategy that enabled us to synthesize three types of morphologically different ZnONPs (spherical/ 38 nm, floral-like/ 59 nm, and rod-like/ >500 nm); all with high purity, triclinic crystal structure, and negative surface charge; and compared the toxicity with Zn2+ ions. Each pot received two seeds, placed in soil inoculated with N-fixing bacterium (Rhizobium japonicum) and grown in outdoor mesocosm for 120 d. Our findings demonstrated a significant particle size-, morphology-, and concentration-dependent influence of ZnONPs on seed yield, lipid peroxidation, and various antioxidant biomarkers in soybean. Our spherical 38 nm ZnONPs were the most protective compared to the floral-like 59 nm ZnONPs, rod-like >500 nm ZnONPs, and Zn2+ ions, particularly up to 160 mg Zn/kg. However, at the highest concentration of 400 mg Zn/kg, spherical 38 nm ZnONPs elicited the highest oxidative stress responses (H2O2 synthesis, MDA, SOD, CAT, POX) in soybean compared to the other two morphologically different ZnONPs tested. The concentration-response curves for the three types of ZnONPs and Zn2+ ions were nonlinear (nonmonotonous) for all the endpoints evaluated. The weight of evidence also suggested a differential nano-specific toxicity of ZnONPs compared to ionic Zn2+ toxicity in soybean. Our higher no-observed-adverse-effect-level (NOAEL) of 160 mg Zn/kg indicates the potential for using ZnONPs as a novel nanofertilizer for crops grown in Zn-deficient soils to improve crop yield, food quality and address malnutrition, globally.

Selenium and Nano-Selenium Biofortification for Human Health: Opportunities and Challenges

Selenium is an essential micronutrient required for the health of humans and lower plants, but its importance for higher plants is still being investigated. The biological functions of Se related to human health revolve around its presence in 25 known selenoproteins (e.g., selenocysteine or the 21st amino acid). Humans may receive their required Se through plant uptake of soil Se, foods enriched in Se, or Se dietary supplements. Selenium nanoparticles (Se-NPs) have been applied to biofortified foods and feeds. Due to low toxicity and high efficiency, Se-NPs are used in applications such as cancer therapy and nano-medicines. Selenium and nano-selenium may be able to support and enhance the productivity of cultivated plants and animals under stressful conditions because they are antimicrobial and anti-carcinogenic agents, with antioxidant capacity and immune-modulatory efficacy. Thus, nano-selenium could be inserted in the feeds of fish and livestock to improvise stress resilience and productivity. This review offers new insights in Se and Se-NPs biofortification for edible plants and farm animals under stressful environments. Further, extensive research on Se-NPs is required to identify possible adverse effects on humans and their cytotoxicity.

Exposure of biosynthesized nanoscale ZnO to Brassica juncea crop plant: morphological, biochemical and molecular aspects

The present work describes the in vitro synthesis and characterization of Zinc oxide nanoparticles (ZnO NPs) using an enzyme alpha amylase, the synthesized nanoparticles were used to study their beneficial effect in the growth and development of Brassica juncea. Transmission Electron Microscope (TEM) image reveals the average size of ZnO NPs was 11 nm and X-ray powder diffraction (XRD) suggests nanoparticles were crystalline in nature. In-silico study confirmed lysine, glutamine and tyrosine present in alpha amylase enzyme, plays a crucial role in the reduction of Zinc acetate dihydrate to ZnO NPs. The biochemical parameters and oxidative enzymes of Brassica juncea were compared with ZnO NPs treated plants. The effect of ZnO NPs on the cellular expression of metal tolerant protein (BjMTP) and cation efflux transporter gene (BjCET2) was also studied. The results indicate that nanoparticles can be used as a replacement for traditional harmful chemical fertilizers.

Development of ZnO Nanoparticles as an Efficient Zn Fertilizer: Using Synchrotron-Based Techniques and Laser Ablation to Examine Elemental Distribution in Wheat Grain

Zinc (Zn) deficiency is an important problem worldwide, adversely impacting human health. Using a field trial in China, we compared the foliar application of both ZnO nanoparticles (ZnO-NPs) and ZnSO₄ on winter wheat (Triticum aestivum L.) for increasing the Zn concentration within the grain. We also used synchrotron-based X-ray fluorescence microscopy and laser ablation inductively coupled plasma mass spectrometry to examine the distribution of Zn within the grain. We found that ZnO-NPs increase the Zn concentration in the wheat grain, increasing from 18 mg·kg^-1 in the control up to 40 mg·kg^-1 when the ZnO-NPs were applied four times. These grain Zn concentrations in the ZnO-NP-treated grains are similar to those recommended for human consumption. However, the ZnO-NPs were similar in their effectiveness to ZnSO₄. When examining trace element distribution in the grain, the trace elements were found to accumulate primarily in the aleurone layer and the crease region across all treatments. Importantly, Zn concentrations in the grain endosperm increased by nearly 30-fold relative to the control, with markedly increasing Zn concentrations within the edible portion. These results demonstrate that ZnO-NPs are a suitable fertilizer for increasing Zn within wheat grain and can potentially be used to improve human nutrition.

Ecological criteria for zinc in Chinese soil as affected by soil properties

The increasing accumulation of zinc (Zn) in agricultural soils has led to the need to assess the potential risk of this element for terrestrial organisms. However, the soil ecological criteria in agricultural soil as a function of soil properties have been sparsely reported. In the present study, we derived the ecological criteria (expressed as predicted no effect concentration (PNEC)) for Zn in soils, based on ecotoxicity data for 19 terrestrial species in Chinese soils, the effect of soil properties on Zn ecotoxicity, differences in species sensitivity, and differences between laboratory and realistic field conditions. First, all ecotoxicity data of Zn for terrestrial organisms in Chinese soils were collected and filtered with given criteria to obtain reliable database. Second, the ecotoxicity data were normalized using Zn ecotoxicity predictive models to eliminate the effect of soil properties on Zn ecotoxicity, and corrected with leaching and aging factors to minimize the differences in Zn ecotoxicity under laboratory and field conditions. Then, species sensitivity distribution (SSD) curves were generated with a Burr Ⅲ function based on corrected ecotoxicity data. The concentration of Zn in soil that provides ecological safety for (100 - x)% of species (HC_x), was calculated from the SSD curve and HC₅ was used for estimation of PNEC. Finally, we developed the predictive models for HC_x by quantifying the relationship between the Zn HC_x and soil properties. Results showed that soil pH was the most crucial factor affecting Zn HC_x values, with HC₅ values varying from 38.3 mg/kg in an acidic soil to 263.3 mg/kg in an alkaline calcareous soil. Both the two-factor (soil pH and OC) and the three-factor (soil pH, OC and CEC) models predicted HC_x values well, with determination coefficients (R²) of 0.941-0.959 and 0.978-0.982, respectively. This study provides a scientific and reliable basis for the improvement of ecological risk assessment and the establishment of soil environmental quality standards.

Particle size and concentration dependent toxicity of copper oxide nanoparticles (CuONPs) on seed yield and antioxidant defense system in soil grown soybean (Glycinemax cv. Kowsar)

Increasing applications of engineered nanomaterials (ENMs) warrant lifecycle assessment of their potential toxicity. Herein, we investigated potential phytotoxicity of copper oxide nanoparticles (CuONPs) on seed yield, focusing on particle size- and concentration-dependent responses of multiple antioxidant defense biomarkers, in soil-grown Glycinemax (cv. Kowsar) during its lifecycle. To this end, we synthesized three distinct sizes CuONPs (25, 50 and 250 nm): all with high purity, monoclinic crystal structure, and same surface charge. Each pot received two seeds, placed in soil inoculated with N-fixing bacteria (Rhizobium japonicum) and grown outdoor for 120 days. Our results show lipid peroxidation (MDA) and several antioxidant biomarkers (SOD, CAT, POX, APX) were differentially altered by the copper compound type, concentrations, and their interactions (p < 0.01). We show particle size- and concentration-dependent influence of CuONPs on lipid peroxidation, and such antioxidant biomarkers including SOD, CAT, POX, and APX, in soybean leaf at 120-day post-plantation. Particularly, the effects of CuONP-25 were consistently higher for most antioxidant biomarkers tested compared to the two larger size CuONPs (CuONP-50, CuONP-250) or Cu2+ ions treatments. We show that the concentration-response curves for CuONP-25 and Cu2+ ions were linear (R2 > 0.65), unlike for the larger size CuONPs (CuONP-50, CuONP-250) the relationships were nonlinear (R2 < 0.45), for most antioxidant biomarkers. The concentration-response curves for seed yield for all types of Cu compounds were linear (R2 > 0.65). Soybean seed yield also mirrored particle size- and concentration-dependent inhibition with CuONPs, and inhibition of CuONP-25 was significantly higher than the two larger size CuONPs or Cu2+ ions at all concentrations tested. All in all, our findings indicate differential nano-specific toxicity compared to ionic Cu2+ toxicity in soybean. These results may guide researchers and regulators on how best to tailor ENMs with specific particle characteristics rendering them more or less toxic, and better inform risk assessment of CuONPs in soil grown food crops such as soybean.

Insights into the tolerance and phytoremediation potential of Coronopus didymus L. (Sm) grown under zinc stress

Zinc (Zn) is a vital micronutrient for plants, but its abundance can be calamitous. In this study, a screenhouse experiment was conducted over a 6-week period to assess the effect of soil enrichment with Zn regimes (100, 250 and 500 mg kg^-1) on growth, Zn accumulation, photosynthetic pigment concentration, oxidative stress markers and activities of antioxidant enzymes in Coronopus didymus. Results revealed that Zn concentration in C. didymus roots and shoots reached up to 1848 mg kg^-1 DW and 1845 mg kg^-1 DW at 500 mg kg^-1 Zn regime, respectively. The plant growth (root-shoot length and biomass) increased, while leaf pigment concentration and soluble protein content in C. didymus tissues decreased progressively with the increased Zn regimes in the soil. At 500 mg kg^-1 Zn regime, hydrogen peroxide and malondialdehyde level increased ∼219% and 111% in roots, while ∼170% and 105% in shoots, with respect to the control. Likewise, superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase and glutathione reductase activities increased significantly with elevated Zn levels. Contrarily, compared to the control, CAT activity declined gradually and reached a minimum of ∼45% in roots and 12% in shoots under highest Zn regime. The results suggested that C. didymus displayed high Zn accumulation and emerged as a tolerant plant species towards Zn stress. Elevated Zn regimes provoked reactive oxygen species generation in C. didymus tissues which was effectively neutralised and scavenged by the antioxidant enzymes, thus marked its efficacy to be potentially employed in phytoremediation and reclamation of Zn-contaminated soils.

Ecological risk of copper and zinc and their different bioavailability change in soil-rice system as affected by biowaste application

A large amount of organic fertilizer application could be accompanied by soil contamination caused by trace heavy metals. A field experiment was carried out in this study to examine the accumulation and availability of copper (Cu) and zinc (Zn) in soil, and their uptake by rice under continuous application of chicken manure, pig manure and sewage sludge. Results showed that after four years of chicken manure, pig manure and sewage sludge application, the soil Cu accumulation rates were 0.15-1.17 mg kg^-1 yr^-1, 1.01-4.22 mg kg^-1 yr^-1 and 0.13-1.15 mg kg^-1 yr^-1, respectively; Zn accumulation rates were 0.54-5.46 mg kg^-1 yr^-1, 1.51-9.65 mg kg^-1 yr^-1 and 1.13-10.47 mg kg^-1 yr^-1, respectively. Compared to the control, the chicken- and pig manure treatments significantly decreased the DTPA-extractable Cu, but increased the DTPA-extractable Zn in soils; thus decreased the Cu contents in rice grain by 2.2-40.6% and increased the grain Zn by 2.6-30.9%, respectively, with increasing application rates and number of years. The addition of sewage sludge significantly increased bioavailability of Zn in soil and its accumulation in rice, while had limited effect on Cu bioavailability. Results suggested that the continuous application of organic fertilizer with elevated Cu and Zn contents at high application rates can induce their accumulation in soil and affect their bioavailability differently.

Template-free microwave-assisted hydrothermal synthesis of manganese zinc ferrite as a nanofertilizer for squash plant (Cucurbita pepo L)

Manganese, zinc, and iron are the most essential micronutrients required for plant growth and applied as foliar fertilizers. Herein, a simple template-free microwave-assisted hydrothermal green synthesis technique was adapted to produce manganese zinc ferrite nanoparticles (Mn0.5Zn0.5Fe2O4 NPs) at different temperatures (100, 120, 140, 160 and 180 °C). The prepared nanomaterials were employed at different concentrations (0, 10, 20, and 30 ppm) as foliar nanofertilizers during the squash (Cucurbita pepo L) planting process. X-ray diffraction patterns of the prepared nanomaterials confirmed successful production of the nanoferrite material. The prepared nanofertilizers showed type IV adsorption isotherm characteristic for mesoporous materials. FE-SEM and HR-TEM imaging showed that the nanoparticles were cubic shaped and increased in particle size with the increase in microwave temperature during production. The impact of application of the synthesized ferrite nanoparticles on vegetative growth, proximate analysis, minerals content and the yield of squash plant was investigated for two consecutive successful planting seasons. The nanoferrite synthesized at 160 °C and applied to the growing plants at a concentration of 10 ppm gave the highest increase in % yield (49.3 and 52.9%) compared to the untreated squash for the two consecutive seasons, whereas the maximum organic matter content (73.0 and 72.5%) and total energy (260 and 258.3 kcal/g) in squash leaves were obtained in plants treated with 30 ppm ferrite nanoparticles synthesized at 180 °C. On the other hand, the maximum organic matter content (76.6 and 76.3%) and total energy (253.6 and 250.3 kcal/g) in squash fruits were attained with plants supplied by 20 ppm ferrite nanoparticles synthesized at 160 °C. These results indicate that the simple template-free microwave-assisted hydrothermal green synthesis technique for the production of manganese zinc ferrite nanoparticles yields nanoparticles appropriate for use as fertilizer for Cucurbita pepo L.

Different factors determined the toxicokinetics of organic chemicals and nanomaterials exposure to zebrafish (Danio Rerio)

Little is known about how the chemical properties (molecular structure, such as the hydrophobic and hydrophilic end group for organic chemical, and particle size for nanomaterials (NMs)) quantitatively affect the toxicokinetics (TK) in organisms especially in short-term, single-species studies. A novel method based on a first-order one compartment TK model which described the monophasic uptake pattern and two-compartment TK model which adequately described the biphasic metabolism pattern was used to determine the bioconcentration and TK rate constants of organic compounds (n = 17) and nanomaterials (NMs, n = 7) in zebrafish. For both one and two compartment model, the uptake (k_in) and elimination (k_out) rate constants were fitted using a one- and two-compartment first-order kinetic model, and bioconcentration factors (BCF) and 95% depuration times (t₉₅) for all tested chemicals were calculated, respectively. The results showed that there was significant difference in TK parameters k_in, k_out, and BCF between organic chemicals and nano metal oxides. For organic compounds, significant correlations were found between the k_in and BCF and the octanol-water partition coefficient (K_ow) and molecular mass. For nano metal oxides, there was a significant negative correlation between the k_in or BCF and particle size, but a positive correlation between k_in and Zeta potential of nanoparticles and also a significant positive correlation between k_out and particle size or specific surface area. Those findings indicated that NMs particle size does matter in biological influx and efflux processes. Our results suggest that the TK process for organic compound and NMs are correlated by different chemical properties and highlight that the K_ow, the absorption k_in, metabolism k₁₂ and k₂₁, elimination rate k_out, and all the parameters that enable the prediction and partitioning of chemicals need to be precisely determined in order to allow an effective TK modeling. It would therefore appear that the TK process of untested chemicals by a fish may be extrapolated from known chemical properties.

Green Synthesis of Nanofertilizers and Their Application as a Foliar forCucurbita pepoL

The implementation of nanofertilizers in agriculture is the purpose in specific to decrease mineral losses in fertilizing and raises the yield during mineral management as well as supporting agriculture development. Hence, this experiment was conducted in Shebin El-Kom, El-Monifia governorate, Egypt, during two seasons 2017 and 2018 to study the effect of micronutrient oxide nanoparticles of zinc, iron, and manganese, as well as combination between these oxides as a foliar application on the growth, yield, and quality of squash plants. The obtained results showed that the spraying of manganese oxide nanoparticles on the plants led to the best vegetative growth characteristics, also, the characteristics of the fruits, yield, and the content of photosynthetic pigments. On the contrary, the content of organic matter, protein, lipids, and energy gave the highest value in squash fruits that have been sprayed with iron oxide nanoparticles.

The effect of white kidney bean fertilized with nano-zinc on nutritional and biochemical aspects in rats

This study aims to estimate the safety of white kidney bean (WKB) fertilized by zinc oxide nanoparticles (ZnO-NPs) via studying changes of liver and kidney function, lipid profile and histological examination for the liver and kidney tissue in rats fed on it. Twenty Four male albino rats were used in this study divided into four groups; the first fed balanced diet (control group), the second fed WKB treated with normal ZnO (nWKB), the third fed WKB treated with 20 ppm ZnO-NPs (tWKB-1), and the fourth fed WKB treated with 40 ppm ZnO-NPs (tWKB-2). The results revealed that WKB treated with ZnO-NPs reduced body weight, food efficiency ratio, relative liver weight, and relative spleen weight were increased as well as the most biochemical parameters exhibited non-significant changes as compared to control group. Meanwhile, tWKB-2 group demonstrated a decrease in alkaline phosphatase and aspartate transaminase activities as compared to nWKB group.

Applications of Nanotechnology in Plant Growth and Crop Protection: A Review

In the era of climate change, global agricultural systems are facing numerous, unprecedented challenges. In order to achieve food security, advanced nano-engineering is a handy tool for boosting crop production and assuring sustainability. Nanotechnology helps to improve agricultural production by increasing the efficiency of inputs and minimizing relevant losses. Nanomaterials offer a wider specific surface area to fertilizers and pesticides. In addition, nanomaterials as unique carriers of agrochemicals facilitate the site-targeted controlled delivery of nutrients with increased crop protection. Due to their direct and intended applications in the precise management and control of inputs (fertilizers, pesticides, herbicides), nanotools, such as nanobiosensors, support the development of high-tech agricultural farms. The integration of biology and nanotechnology into nonosensors has greatly increased their potential to sense and identify the environmental conditions or impairments. In this review, we summarize recent attempts at innovative uses of nanotechnologies in agriculture that may help to meet the rising demand for food and environmental sustainability.

Applications of Nanotechnology in Plant Growth and Crop Protection: A Review

In the era of climate change, global agricultural systems are facing numerous, unprecedented challenges. In order to achieve food security, advanced nano-engineering is a handy tool for boosting crop production and assuring sustainability. Nanotechnology helps to improve agricultural production by increasing the efficiency of inputs and minimizing relevant losses. Nanomaterials offer a wider specific surface area to fertilizers and pesticides. In addition, nanomaterials as unique carriers of agrochemicals facilitate the site-targeted controlled delivery of nutrients with increased crop protection. Due to their direct and intended applications in the precise management and control of inputs (fertilizers, pesticides, herbicides), nanotools, such as nanobiosensors, support the development of high-tech agricultural farms. The integration of biology and nanotechnology into nonosensors has greatly increased their potential to sense and identify the environmental conditions or impairments. In this review, we summarize recent attempts at innovative uses of nanotechnologies in agriculture that may help to meet the rising demand for food and environmental sustainability.