Effects of Copper Oxide Nanoparticles on the Growth of Rice (Oryza Sativa L.) Seedlings and the Relevant Physiological Responses

Interaction of plants and metal nanoparticles: Exploring its molecular mechanisms for sustainable agriculture and crop improvement

Metal nanoparticles offer promising prospects in agriculture, enhancing plant growth and ensuring food security. Silver, gold, copper, and zinc nanoparticles possess unique properties making them attractive for plant applications. Understanding molecular interactions between metal nanoparticles and plants is crucial for unlocking their potential to boost crop productivity and sustainability. This review explores metal nanoparticles in agriculture, emphasizing the need to understand these interactions. By elucidating mechanisms, it highlights the potential for enhancing crop productivity, stress tolerance, and nutrient-use efficiency, contributing to sustainable agriculture and food security. Quantifying benefits and risks reveal significant advantages. Metal nanoparticles enhance crop productivity by 20% on average and reduce disease incidence by up to 50% when used as antimicrobial agents. They also reduce nutrient leaching by 30% and enhance soil carbon sequestration by 15%, but concerns about toxicity, adverse effects on non-target organisms, and nanoparticle accumulation in the food chain must be addressed. Metal nanoparticles influence cellular processes including sensing, signaling, transcription, translation, and post-translational modifications. They act as signaling molecules, activate stress-responsive genes, enhance defense mechanisms, and improve nutrient uptake. The review explores their catalytic role in nutrient management, disease control, precision agriculture, nano-fertilizers, and nano-remediation. A bibliometric analysis offers insights into the current research landscape, highlighting trends, gaps, and future directions. In conclusion, metal nanoparticles hold potential for revolutionizing agriculture, enhancing productivity, mitigating environmental stressors, and promoting sustainability. Addressing risks and gaps is crucial for their safe integration into agricultural practices.

Toxicological effects of nanoparticles in plants: Mechanisms involved at morphological, physiological, biochemical and molecular levels

The rapid advancement of nanotechnology has led to unprecedented innovations across diverse industries, including pharmaceuticals, agriculture, cosmetics, electronics, textiles, and food, owing to the unique properties of nanoparticles. The extensive production and unregulated release of synthetic nanoparticles may contribute to nanopollution within the ecosystem. In the agricultural sector, nanotechnology is increasingly utilized to improve plant productivity, enhance resistance to stressors, and reduce the usage of chemicals. However, the uncontrolled discharge of nanoparticles into the natural environment raises concerns regarding possible plant toxicological impacts. The review focuses on the translocation of these particles within the plants, emphasizing their phytotoxicological effects at morphological, physiological, biochemical, and molecular levels. Eventhough the beneficial aspects of these nanoparticles are evident, excessive usage of nanoparticles at higher concentrations may lead to potential adverse effects. The phytotoxicity resulting from excessive amounts of nanoparticles affects seed germination and biomass production, disrupts the photosynthesis system, induces oxidative stress, impacts cell membrane integrity, alters gene expression, causes DNA damage, and leads to epigenetic variations in plants. Nanoparticles are found to directly associate with the cell membrane and cell organelles, leading to the dissolution and release of toxic ions, generation of reactive oxygen species (ROS) and subsequent oxidative stress. The present study signifies and accumulates knowledge regarding the application of nanoparticles in agriculture and illustrates a clear picture of their possible impacts on plants and soil microbes, thereby paving the way for future developments in nano-agrotechnology. The review concludes by addressing current challenges and proposing future directions to comprehend and mitigate the possible biological risks associated with nanoparticles in agriculture.

Stereoselectivity of paclobutrazol enantiomers to oxidative stress in wheat

Chiral pesticides have the special chiral structures, so enantioselective biological effects are usually observed in living organisms. Current study used paclobutrazol as a case study and explored the enantioselective degradation and oxidative stress effect on wheat. The results demonstrated that the degradation of R-paclobutrazol was faster than S-paclobutrazol significantly and improved the content of MDA and O2 - in wheat plants, which proved that the R-paclobutrazol induced oxidative damage in wheat, showing selective biological effects, and S-paclobutrazol was friendly to wheat. This study provided a theoretical basis for the selective activity of chiral pesticides and the development of chiral pesticide monomers.

Environmental behaviors and toxic mechanisms of engineered nanomaterials in soil

Engineered nanomaterials (ENMs) are inevitably released into the environment with the exponential application of nanotechnology. Parts of ENMs eventually accumulate in the soil environment leading to potential adverse effects on soil ecology, crop production, and human health. Therefore, the safety application of ENMs on soil has been widely discussed in recent years. More detailed safety information and potential soil environmental risks are urgently needed. However, most of the studies on the environmental effects of metal-based ENMs have been limited to single-species experiments, ecosystem processes, or abiotic processes. The present review formulated the source and the behaviors of the ENMs in soil, and the potential effects of single and co-exposure ENMs on soil microorganisms, soil fauna, and plants were introduced. The toxicity mechanism of ENMs to soil organisms was also reviewed including oxidative stress, the release of toxic metal ions, and physical contact. Soil properties affect the transport, transformation, and toxicity of ENMs. Toxic mechanisms of ENMs include oxidative stress, ion release, and physical contact. Joint toxic effects occur through adsorption, photodegradation, and loading. Besides, future research should focus on the toxic effects of ENMs at the food chain levels, the effects of ENMs on plant whole-lifecycle, and the co-exposure and long-term toxicity effects. A fast and accurate toxicity evaluation system and model method are urgently needed to solve the current difficulties. It is of great significance for the sustainable development of ENMs to provide the theoretical basis for the ecological risk assessment and environmental management of ENMs.

Modulation of terpenoid indole alkaloid pathway via elicitation with phytosynthesized silver nanoparticles for the enhancement of ajmalicine, a pharmaceutically important alkaloid

MAIN CONCLUSION

The use of silver nanoparticles as elicitors in cell cultures of Rauwolfia serpentina resulted in increased levels of ajmalicine, upregulated structural and regulatory genes, elevated MDA content, and reduced activity of antioxidant enzymes. These findings hold potential for developing a cost-effective method for commercial ajmalicine production. Plants possess an intrinsic ability to detect various stress signals, prompting the activation of defense mechanisms through the reprogramming of metabolites to counter adverse conditions. The current study aims to propose an optimized bioprocess for enhancing the content of ajmalicine in Rauwolfia serpentina callus through elicitation with phytosynthesized silver nanoparticles. Initially, callus lines exhibiting elevated ajmalicine content were established. Following this, a protocol for the phytosynthesis of silver nanoparticles using seed extract from Rauwolfia serpentina was successfully standardized. The physicochemical attributes of the silver nanoparticles were identified, including their spherical shape, size ranging from 6.7 to 28.8 nm in diameter, and the presence of reducing-capping groups such as amino, carbonyl, and amide. Further, the findings indicated that the presence of 2.5 mg L-1 phytosynthesized silver nanoparticles in the culture medium increased the ajmalicine content. Concurrently, structural genes (TDC, SLS, STR, SGD, G10H) and regulatory gene (ORCA3) associated with the ajmalicine biosynthetic pathway were observed to be upregulated. A notable increase in MDA content and a decrease in the activities of antioxidant enzymes were observed. A notable increase in MDA content and a decrease in the activities of antioxidant enzymes were also observed. Our results strongly recommend the augmentation of ajmalicine content in the callus culture of R. serpentina through supplementation with silver nanoparticles, a potential avenue for developing a cost-effective process for the commercial production of ajmalicine.

Inhibitory impact of MgO nanoparticles on oxidative stress and other physiological attributes of spinach plant grown under field condition

Green synthesis of NPs is preferred due to its eco-friendly procedures and non-toxic end products. However, unintentional release of NPs can lead to environmental pollution affecting living organisms including plants. NPs accumulation in soil can affect the agricultural sustainability and crop production. In this context, we report the morphological and biochemical response of spinach nanoprimed with MgO-NPs at concentrations, 10, 50, 100, and 150 µg/ml. Nanopriming reduced the spinach root length by 14-26%, as a result a reduction of 20-74% in the length of spinach shoots was observed. The decreased spinach shoot length inhibited the chlorophyll accumulation by 21-55%, thus reducing the accumulation of carbohydrates and yield by 46 and 49%, respectively. The reduced utilization of the total absorbed light further enhanced ROS generation and oxidative stress by 32%, thus significantly altering their antioxidant system. Additionally, a significant variation in the accumulation of flavonoid pathway downstream metabolites myricitin, rutin, kaempferol-3 glycoside, and quercitin was also revealed on MgO-NPs nanopriming. Additionally, NPs enhanced the protein levels of spinach probably as an osmoprotectant to regulate the oxidative stress. However, increased protein precipitable tannins and enhanced oxidative stress reduced the protein digestibility and solubility. Overall, MgO-NPs mediated oxidative stress negatively affected the growth, development, and yield of spinach in fields in a concentration dependent manner.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01391-9.

Effects of CuO nanoparticles in composted sewage sludge on rice-soil systems and their potential human health risks

The release of metal-based nanoparticles (MNPs) into sewage systems is worrisome due to their potential impact on crop-soil systems that are amended with sewage sludge. This study aimed to investigate the effects of copper oxide nanoparticles (CuO NPs) in composted sewage sludge (CSS) on rice-soil systems and to assess the health risks associated with consuming CuO NP-contaminated rice produced by CSS amendment. CSS was treated with three doses of CuO NPs, resulting in Cu levels below the sludge limits (1500 mg Cu kg-1) for reuse as a soil amendment. Results showed that CuO NPs in CSS at environmentally acceptable levels had no negative effect on rice growth and yield. In fact, they enhanced biomass production, tillering capacity, and soil fertility by increasing N and K levels in the soil. In addition, CuO NPs in CSS (450-1450 mg Cu kg-1) promoted the accumulation of macro- and micro-minerals in rice grains, thereby improving the nutritional value of rice. However, Cu contamination in CSS led to elevated levels of toxic metals, especially As, in rice grains, posing potential health risks to both adults and children. In the presence of higher CuO NPs contamination in CSS, the hazard quotient of As exceeded one, indicating an increased risks of toxic metal exposure via rice consumption. This study raises concerns about potential long-term threats to human health posed by MNPs contamination in CSS and highlights the need to reevaluate the permissible limits of hazardous elements in sludge to ensure its safe reuse in agriculture.

Zinc oxide nanoparticles mitigated the arsenic induced oxidative stress through modulation of physio-biochemical aspects and nutritional ions homeostasis in rice (Oryza sativa L.)

Zinc oxide nanoparticles (nZn) have emerged as vital agents in combating arsenic (As) stress in plants. However, their role in mitigation of As induced oxidative stress is less studied. Therefore, this study aimed to assess the comparative role of nZn and ZnO in alleviating As toxicity in rice genotype "9311". The results of this study revealed that nZn demonstrated superior efficacy compared to ZnO in mitigating As toxicity. This superiority can be attributed to the unique size and structure of nZn, which enhances its ability to alleviate As toxicity. Exposure to As at a concentration of 25 μM L-1 led to significant reductions in shoot length, root length, shoot dry weight, and root dry weight by 39%, 51%, 30%, and 46%, respectively, while the accumulation of essential nutrients such as magnesium (Mg), potassium (K), iron (Fe), manganese (Mn), and zinc (Zn) decreased by 25%-47% compared to the control plants. Additionally, As exposure resulted in stomatal closure and structural damage to vital cellular components such as grana thylakoids (GT), starch granules (SG), and the nucleolus. However, the application of nZn at a concentration of 30 mg L-1 exhibited significant alleviation of As toxicity, resulting in a reduction of As accumulation by 54% in shoots and 62% in roots of rice seedlings. Furthermore, nZn demonstrated the ability to scavenge reactive oxygen species (ROS) like hydrogen peroxide (H2O2) and superoxide anion (O2.-), while significantly promoted the gas exchange parameters, chlorophyll content (SPAD value), fluorescence efficiency (Fv/m) and antioxidant enzyme activities under As-induced stress. These findings highlight the potential of nZn in mitigating the adverse impacts of As contamination in rice plants. However, further research is necessary to fully comprehend the underlying mechanisms responsible for the protective effects of nZn and to determine the optimal conditions for their application in real-world agricultural settings.

Favorable physiological and morphological effects of molybdenum nanoparticles on tobacco (Nicotiana tabacum L.): root irrigation is superior to foliar spraying

Introduction

Nano fertilizers can provide efficient solutions to the increasing problem of nutrient deficiency caused by low availability. However, the most important prerequisite is to fully understand whether nanomaterials induce phytotoxicity in plants under a variety of different conditions. The mechanisms underlying interactions between molybdenum nanoparticles (Mo NPs) and plants with respect to their uptake and biological effects on crops are still not fully understood.

Methods

In this study, the impacts of Mo NPs over a range of concentrations (0, 25, and 100 μg/mL) on tobacco (Nicotiana tabacum L.) seedling growth were comparatively evaluated under foliar applications and root irrigation.

Results

The results indicated that more significant active biological effects were observed with root irrigation application of Mo NPs than with foliar spraying. The agronomic attributes, water content and sugar content of Mo NPs-exposed seedlings were positively affected, and morphologically, Mo NPs induced root cell lignification and more vascular bundles and vessels in tobacco tissues, especially when applied by means of root irrigation. Moreover, the photosynthetic rate was improved by 131.4% for root exposure to 100 μg/mL Mo NPs, mainly due to the increased chlorophyll content and stomatal conductance. A significant concentration-dependent increase in malonaldehyde (MDA) and defensive enzyme activity for the Mo NPs-treated tobacco seedlings were detected compared to the controls. Significantly improved absorption of Mo by exposed tobacco seedlings was confirmed with inductively coupled plasma mass spectrometry (ICP-MS) in tobacco tissues, regardless of application method. However, the accumulation of Mo in roots increased by 13.94 times, when roots were exposed to 100 mg/L Mo NPs, higher than that under treatment with foliar spray. Additionally, Mo NPs activated the expression of several genes related to photosynthesis and aquaporin processes.

Discussion

The present investigations offer a better understanding of Mo NPs-plant interactions in terrestrial ecosystems and provide a new strategy for the application of Mo NPs as nano fertilizers in crop production.

Application of green synthesized bimetallic nZVI-Cu nanoparticle as a sustainable alternative to chemical fertilizers to enhance growth and photosynthetic efficiency of rice seedlings

Application of nanomaterials in agriculture has been extensively explored over the past decade leading to a wide ambit of nanoparticle-based agrochemicals. Metallic nanoparticles consisting of plant macro- and micro-nutrients have been used as nutritional supplements for plants through soil amendments, foliar sprays, or seed treatment. However, most of these studies emphasize monometallic nanoparticles which limit the range of usage and effectivity of such nanoparticles (NPs). Hence, we have employed a bimetallic nanoparticle (BNP) consisting of two different micro-nutrients (Cu & Fe) in rice plants to test its efficacy in terms of growth and photosynthesis. Several experiments were designed to assess growth (root-shoot length, relative water content) and photosynthetic parameters (pigment content, relative expression of rbcS, rbcL & ChlGetc.). To determine whether the treatment induced any oxidative stress or structural anomalies within the plant cells, histochemical staining, anti-oxidant enzyme activities, FTIR, and SEM micrographs were undertaken. Results indicated that foliar application of 5 mg L-1 BNP increased vigor and photosynthetic efficiency whereas 10 mg L-1 concentration induced oxidative stress to some extent. Furthermore, the BNP treatment did not perturb the structural integrity of the exposed plant parts and also did not induce any cytotoxicity. Application of BNPs in agriculture has not been explored extensively to date and this study is one of the first reports that not only documents the effectivity of Cu-Fe BNP but also critically explores the safety of its usage on rice plants making it a useful lead to design new BNPs and explore their efficacy.

Essential oil-grafted copper nanoparticles as a potential next-generation fungicide for holistic disease management in maize

Sustainable food production is necessary to meet the demand of the incessantly growing human population. Phytopathogens pose a major constraint in food production, and the use of conventional fungicides to manage them is under the purview of criticism due to their numerous setbacks. In the present study, essential oil-grafted copper nanoparticles (EGC) were generated, characterized, and evaluated against the maize fungal pathogens, viz., Bipolaris maydis, Rhizoctonia solani f. sp. sasakii, Macrophomina phaseolina, Fusarium verticillioides, and Sclerotium rolfsii. The ED₅₀ for the fungi under study ranged from 43 to 56 μg ml^-1, and a significant inhibition was observed at a low dose of 20 μg ml^-1 under in vitro conditions. Under net house conditions, seed treatment + foliar spray at 250 and 500 mg L^-1 of EGC performed remarkably against maydis leaf blight (MLB), with reduced percent disease index (PDI) by 27.116 and 25.292%, respectively, in two Kharif seasons (May-Sep, 2021, 2022). The activity of enzymatic antioxidants, viz., β-1, 3-glucanase, PAL, POX, and PPO, and a non-enzymatic antioxidant (total phenolics) was increased in treated maize plants, indicating host defense was triggered. The optimum concentrations of EGC (250 mg L^-1 and 500 mg L^-1) exhibited improved physiological characteristics such as photosynthetic activity, shoot biomass, plant height, germination percentage, vigor index, and root system traits. However, higher concentrations of 1,000 mg L^-1 rendered phytotoxicity, reducing growth, biomass, and copper bioaccumulation to high toxic levels, mainly in the foliar-sprayed maize leaves. In addition, EGC and copper nanoparticles (CuNPs) at 1,000 mg L^-1 reduced the absorption and concentration of manganese and zinc indicating a negative correlation between Cu and Mn/Zn. Our study proposes that the CuNPs combined with EO (Clove oil) exhibit astounding synergistic efficacy against maize fungal pathogens and optimized concentrations can be used as an alternative to commercial fungicides without any serious impact on environmental health.

Interference Effects of Commercial Persistent Luminescence Materials on Rice Germination and Seedling Growth

Persistent luminescence materials (PLMs) are widely used across a multitude of fields due to their distinct optical properties. However, like other micron-sized materials such as microplastics, the production and recycling processes of PLMs can lead to their accumulation in soil and water, potentially posing detrimental effects on plant growth and development. In this study, we investigated the impact of commercially available blue PLM (bPLM), green PLM (gPLM), and red PLM (rPLM) on germination, seedling growth, and oxidative stress responses in rice. Our findings demonstrate that the morphology and size of PLMs do not significantly differ in their effects on rice growth. All three types of PLMs significantly inhibited root length and stem length, disrupted root cell structures, and decreased seedling biomass. Interestingly, gPLM and bPLM were found to stimulate the synthesis of osmolytes and chlorophyll in rice, while rPLM had the opposite effect. Changes in the antioxidant enzyme system in rice clearly indicated that the three types of PLMs induced reactive oxygen species (ROS) damage in rice. This study enhances our understanding of the potential environmental impacts of PLMs, offering valuable insights for the safe and responsible use of these materials in various applications.

A Comprehensive Review on Significance and Advancements of Antimicrobial Agents in Biodegradable Food Packaging

Food waste is key global problem and more than 90% of the leftover waste produced by food packaging factories is dumped in landfills. Foods packaged using eco-friendly materials have a longer shelf life as a result of the increased need for high-quality and secure packaging materials. For packaging purposes, natural foundation materials are required, as well as active substances that can prolong the freshness of the food items. Antimicrobial packaging is one such advancement in the area of active packaging. Biodegradable packaging is a basic form of packaging that will naturally degrade and disintegrate in due course of time. A developing trend in the active and smart food packaging sector is the use of natural antioxidant chemicals and inorganic nanoparticles (NPs). The potential for active food packaging applications has been highlighted by the incorporation of these materials, such as polysaccharides and proteins, in biobased and degradable matrices, because of their stronger antibacterial and antioxidant properties, UV-light obstruction, water vapor permeability, oxygen scavenging, and low environmental impact. The present review highlights the use of antimicrobial agents and nanoparticles in food packaging, which helps to prevent undesirable changes in the food, such as off flavors, colour changes, or the occurrence of any foodborne outcomes. This review attempts to cover the most recent advancements in antimicrobial packaging, whether edible or not, employing both conventional and novel polymers as support, with a focus on natural and biodegradable ingredients.

Joint effects of CuO nanoparticles and perfluorooctanoic acid on cabbage (Brassica pekinensis L.)

Coexisting nanoparticles (NPs) may change plant accumulation and toxicity of perfluorooctanoic acid (PFOA) in soil, but research is very scarce. In this study, cabbage (Brassica pekinensis L.) was exposed to single or combined treatments of PFOA (2 mg/kg and 4 mg/kg) and copper oxide NPs (nCuO, 200 mg/kg and 400 mg/kg) for 40 days. At harvest, biomass, photosynthesis index, and nutrient composition of cabbage, as well as plant accumulation of PFOA and Cu, were measured. Results showed that nCuO and PFOA were adverse to cabbage growth by decreasing chlorophyll contents, inhibiting photosynthesis and transpiration, and interfering with the utilization of nutrient components. Besides, they also affected each other's plant utilization and transmission. Especially, nCuO at a high dose (400 mg/kg) significantly increased the transport of coexisting PFOA (4 mg/kg) content (by 124.9% and 118.2%) to cabbage shoots. The interaction mechanism between nCuO and PFOA is unknown, and more research is needed to evaluate their composite phytotoxicity.

Indole-3-acetic acid (IAA) doping on the surface of CuO-NPs reduces the toxic effects of NPs on Lactuca sativa

CuO Nanoparticles (CuO NPs) retard the plant growth but at appropriate concentration boosts shoot growth and therefore may function as nano-carrier or nano-fertilizer. To overcome the toxic effects, NPs can be capped with plant growth regulators. In this work, CuO-NPs (30 nm) were synthesized as the carrier and capped with indole-3-acetic acid (IAA) to generate CuO-IAA NPs (30.4 nm) as toxicity mitigant molecules. Seedlings of dicots, Lactuca sativa L. (Lettuce) were exposed to 5, 10 mg Kg-1/ of NPs in the soil to analyze shoot length, fresh and dry weight of shoots, phytochemicals, and antioxidant response. Toxicity to shoot length was recorded at higher concentrations of CuO-NPs, however, a reduction in toxicity was observed for CuO-IAA nanocomposite. Concentration-dependent decrease in the biomass of plants was also observed at higher concentrations of CuO-NPs (10 mg/kg). The antioxidative phytochemicals (phenolics and flavonoids) and antioxidative response increased in plants when exposed to CuO-NPs. However, the presence of CuO-IAA NPs combats the toxic response and a significant decrease in non-enzymatic antioxidants and total antioxidative response and total reducing power potential was observed. The results demonstrate that CuO-NPs can be used as a carrier of hormones for the enhancement of plant biomass and IAA on the surface of NPs reduces the toxic effects on NPs.

Phytotoxic effects of chemically synthesized copper oxide nanoparticles induce physiological, biochemical, and ultrastructural changes in Cucumis melo

Nanotechnology has achieved great attention due to its impressive performance especially engineered nanoparticles (ENPs). Copper-based nanoparticles offer favorable development in the fabrication of agrochemicals including fertilizers and pesticides in the field of agriculture. However, their toxic impact on melon plants (Cucumis melo) still needs to be investigated. Therefore, the aim of the current work was performed to focus on the toxic impact of Cu oxide nanoparticles (CuONPs) in hydroponically grown Cucumis melo. Our results demonstrated that CuONPs with 75, 150, and 225 mg/L significantly (P<0.005) suppressed the growth rate and badly affect physiological and biochemical activities in melon seedlings. Also, results revealed remarkable phenotypical changes besides significantly reduced fresh biomass and decreased levels of total chlorophyll contents in a dose-dependent manner. Atomic absorption spectroscopy (ASS) analysis exhibited that C. melo treated with CuONPs accumulates NPs in the shoot. Moreover, exposure to higher CuONPs (75-225mg/L) significantly increased the reactive oxygen species (ROS) accumulation, malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) level in the shoot and induced toxicity in melon root with an increase in electrolyte leakage. Furthermore, antioxidant enzyme peroxidase (POD) and superoxide dismutase (SOD) activity in the shoot significantly increased under exposure to higher CuONPs. Exposure to higher concentrations of CuONPs (225 mg/L) significantly deformed the stomatal aperture. Furthermore, reducing the number and abnormal size of palisade mesophyll and spongy mesophyll cells were investigated especially at high doses of CuONPs. Overall, our current work demonstrates that CuONPs of 10-40 nm size provide direct evidence for a toxic effect in C. melo seedlings. Our findings were expected to inspire the safe production of NPs and agrifood security. Thus, CuONPs prepared from toxic route and its bioaccumulation into our food chain through crop plants possess a serious threat to the ecological system.

Foliar enrichment of copper oxide nanoparticles promotes biomass, photosynthetic pigments, and commercially valuable secondary metabolites and essential oils in dragonhead (Dracocephalum moldavica L.) under semi-arid conditions

High alkaline and low organic carbon hinder micronutrients, such as copper (Cu), bioavailability in (semi-) arid soils, affecting plant nutrient quality and productivity. This study aimed at investigating the potential beneficial effects of foliar Cu oxide nanoparticles (CuONPs) and conventional chelated-Cu applications (0-400 mg Cu/L) on the biomass, physiological biomarkers of plant productivity and oxidative stress, Cu bioaugmentation, and essential oils and secondary metabolites in dragonhead (Dracocephalum moldavica [L.]) grown in Cu-limited alkaline soil in semi-arid condition. Employing a randomized complete block design with three replicates, two different sources of Cu (CuONPs and chelated-Cu), and a wide range of Cu concentrations (0, 40, 80, 160, and 400 mg Cu/L), plants were foliarly treated at day-60 and day-74. At day-120, plants were harvested at the end of the flowering stage. Results showed shoot Cu bioaccumulation, flavonoids and anthocyanin increased in a dose-dependent manner for both Cu compounds, but the beneficial effects were significantly higher with CuONPs compared to chelated-Cu treatments. Further, shoot biomass (23 %), photosynthetic pigments (chlorophyll-a and chlorophyll-b; 77 and 123 %, respectively), and essential oil content and yield (70 and 104 %, respectively) increased significantly with foliar application of 80 mg/L CuONPs compared to equivalent concentration of chelated-Cu, suggesting an optimal threshold beyond which toxicity was observed. Likewise, commercially important secondary metabolites' yield (such as geranyl acetate, geranial, neral, and geraniol) was higher with 80 mg/L CuONPs compared to 160 mg/L chelated-Cu (2.3, 0.5, 2.5, and 7.1 %, respectively). TEM analyses of leaf ultrastructure revealed altered cellular organelles for both compounds at 400 mg/L, corroborating the results of oxidative stress response (malondialdehyde and H2O2). In conclusion, these findings indicate significantly higher efficacy of CuONPs, with an optimal threshold of 80 mg/L, in promoting essential oil and bioactive compound yield in dragonhead and may pave a path for the use of nano-Cu as a sustainable fertilizer promoting agricultural production in semi-arid soils that are micronutrient Cu deficient.

Potential Effects of Metal Oxides on Agricultural Production of Rice: A Mini Review

The extensive usage of metal oxide nanoparticles has aided in the spread and accumulation of these nanoparticles in the environment, potentially endangering both human health and the agroecological system. This research describes in detail the hazardous and advantageous impacts of common metal oxide nanomaterials, such as iron oxide, copper oxide, and zinc oxide, on the life cycle of rice. In-depth analyses are conducted on the transport patterns of nanoparticles in rice, the plant's reaction to stress, the reduction of heavy metal stress, and the improvement of rice quality by metal oxide nanoparticles, all of which are of significant interest in this subject. It is emphasized that from the perspective of advancing the field of nanoagriculture, the next stage of research should focus more on the molecular mechanisms of the effects of metal oxide nanoparticles on rice and the effects of combined use with other biological media. The limitations of the lack of existing studies on the effects of metal oxide nanomaterials on the entire life cycle of rice have been clearly pointed out.

Ethylene accelerates copper oxide nanoparticle-induced toxicity at physiological, biochemical, and ultrastructural levels in rice seedlings

The enormous use of metal-based nanoparticles (NPs) in different sectors may result in enhanced accumulation in agricultural soil, which could impose negative effects on crop productivity. Hence, strategies are needed to explore the mechanisms of copper oxide nanoparticle (CuO NP)-induced toxicity in crops. The present study aimed to investigate the involvement of ethylene in CuO NP-induced toxicity in rice seedlings. Here, our results indicate that 450 mg L^-1 of CuO NPs induced toxic effects in rice seedlings. Thus, it was evidenced by the reduced plant biomass accumulation, enhanced oxidative stress indicators, and cellular ultrastructural damages. More importantly, the exogenous supply of ethylene biosynthesis and signaling antagonists cobalt (Co) and silver (Ag) respectively provided tolerance and improved the defense system of rice seedlings against CuO NP toxicity. The ethylene antagonists could significantly reduce the extent of ultrastructural and stomatal damage by controlling the ROS accumulation in rice seedlings under CuO NP stress. Furthermore, Co and Ag augmented the antioxidant defense system against CuO NP-induced toxicity. Contrary to that, all oxidative damage attributes were further enhanced exogenous application of ethylene biosynthesis precursor [1-aminocyclopropane-1-carboxylic acid (ACC)] in the presence of CuO NPs. In addition, ACC could increase the CuO NP-induced stomatal and ultrastructural damages by reducing the ROS-scavenging ability in rice seedlings. Taken together, these results indicate the involvement of ethylene in CuO NP-induced toxicity in rice seedlings.

Metabolomics as a Tool to Understand Nano-Plant Interactions: The Case Study of Metal-Based Nanoparticles

Metabolomics is a powerful tool in diverse research areas, enabling an understanding of the response of organisms, such as plants, to external factors, their resistance and tolerance mechanisms against stressors, the biochemical changes and signals during plant development, and the role of specialized metabolites. Despite its advantages, metabolomics is still underused in areas such as nano-plant interactions. Nanoparticles (NPs) are all around us and have a great potential to improve and revolutionize the agri-food sector and modernize agriculture. They can drive precision and sustainability in agriculture as they can act as fertilizers, improve plant performance, protect or defend, mitigate environmental stresses, and/or remediate soil contaminants. Given their high applicability, an in-depth understanding of NPs' impact on plants and their mechanistic action is crucial. Being aware that, in nano-plant interaction work, metabolomics is much less addressed than physiology, and that it is lacking a comprehensive review focusing on metabolomics, this review gathers the information available concerning the metabolomic tools used in studies focused on NP-plant interactions, highlighting the impact of metal-based NPs on plant metabolome, metabolite reconfiguration, and the reprogramming of metabolic pathways.

The responses and detoxification mechanisms of dark septate endophytes (DSE), Exophiala salmonis, to CuO nanoparticles

To understand the tolerance mechanisms of dark septate endophytes (DSE), Exophiala salmonis, to CuO nanoparticles (CuO-NPs) with different sizes (40 and 150 nm), we investigated the morphology, antioxidant response, Cu subcellular distribution, and the melanin gene expression in the mycelia of E. salmonis. E. salmonis was cultured in liquid and solid media under the stress of increasing CuO-NP concentrations (0, 50, 100, 150, and 250 mg/L). Results showed that (1) E. salmonis showed good CuO-NP tolerance, and the tolerance to CuO-NPs at 150 nm was stronger than that at 40 nm. A large number of agglomeration structures were observed on the mycelia surface with the exception of 50 mg/L CuO-NPs with a diameter of 150 nm. (2) CuO-NP stress significantly stimulated the production of antioxidant enzymes, particularly the CuO-NPs with small particle size (40 nm). (3) Cu uptaken by E. salmonis increased proportionally with the increase of CuO-NP concentration in the medium. More than 80% Cu was absorbed in cell wall of mycelia treated with a small particle size (40 nm). (4) FTIR analysis revealed that hydroxyl, amine, carboxyl, and phosphate groups were associated with CuO-NP binding regardless of particle size. (5) Fungal melanin content increased with the addition of CuO-NPs; the increase of melanin induced by CuO-NPs with small particle size (40 nm) was more significant. (6) The expression of 1,3,6,8-tetrahydroxynaphthalene reductase (Arp2) in the melanin synthesis pathway increased under the stress of CuO-NPs, and CuO-NPs with a small particle size (40 nm) caused a significant change in the expression level of Arp2 gene than those with a large particle size (150 nm). In conclusion, E. salmonis had a strong tolerance to CuO-NPs and mitigated the toxic effects of CuO-NPs through the antioxidant system, the expression of genes related to melanin synthesis, and the synthesis of melanin.

Melatonin-mediated resistance to copper oxide nanoparticles-induced toxicity by regulating the photosynthetic apparatus, cellular damages and antioxidant defense system in maize seedlings

The pollution of nanoparticles (NPs) has linked with severe negative effects on crop productivity. Thus, effective strategies are needed to mitigate the phytotoxicity of NPs. The aim of present study was to evaluate the efficacy of exogenously applied melatonin (MT) in mitigating the toxic effects of copper oxide nanoparticles (CuO NPs) from maize seedlings. Therefore, we comprehensively investigated the inhibitory effects of MT against CuO NPs-induced toxicity on morpho-physiological, biochemical and ultrastructural levels in maize. Our results show that CuO NPs (300 mg L^-1) exposure displayed significantly reduction in all plant growth traits and induced toxicity in maize. Furthermore, 50 μM MT provided maximum plant tolerance against CuO NPs-induced phytotoxicity. It was noticed that MT improved plant growth, biomass, photochemical efficiency (Fv/Fm), chlorophyll contents (Chl a and Chl b), SPAD values and gas exchange attributes (stomatal conductance, net photosynthetic rate, intercellular CO₂ concentration and transpiration rate) under CuO NPs stress. In addition, MT enhanced the antioxidant defense system and conferred protection to ultrastructural (mainly chloroplast, thylakoids membrane and plastoglobuli) damages and stomatal closure in maize plants subjected to CuO NPs stress. Together, it can be stated that the exogenous supply of MT improves the resilience of maize plants against the CuO NPs-induced phytotoxicity. Our current findings can be useful for the enhancement of plant growth and yield attributes in CuO NPs-contaminated soils. The reported information can provide insight into the MT pathways that can be used to improve crop stress tolerance in a challenging environment.

OsCERK1 Contributes to Cupric Oxide Nanoparticles Induced Phytotoxicity and Basal Resistance against Blast by Regulating the Anti-Oxidant System in Rice

CuO NPs (cupric oxide nanoparticles) are widely used in various fields due to their high electrical conductivity, electronic correlation effect, and special physical property. Notably, CuO NPs have good application prospects in agricultural production because of its antifungal activity to prevent crop diseases. However, the increasing release of CuO NPs into the environment has resulted in a serious threat to the ecosystem, including plants. Previous studies have reported the toxicity of CuO NPs on rice, but little is known about the underlying molecular mechanisms or specific genes involved in the response to CuO NPs. In this study, we found that the rice well-known receptor Chitin Elicitor Receptor Kinase 1 (OsCERK1), which is essential for basal resistance against pathogens, is involved in CuO NPs stress in rice. Knockout of OsCERK1 gene resulted in enhanced tolerance to CuO NPs stress. Furthermore, it was revealed that OsCERK1 reduces the tolerance to CuO NPs stress by regulating the anti-oxidant system and increasing the accumulation of H₂O₂ in rice. In addition, CuO NPs treatment significantly enhances the basal resistance against M. oryzae which is mediated by OsCERK1. In conclusion, this study demonstrated a dual role of OsCERK1 in response to CuO NPs stress and M. oryzae infection by modulating ROS accumulation, which expands our understanding about the crosstalk between abiotic and biotic stresses.

CuO nanoparticles in irrigation wastewater have no detrimental effect on rice growth but may pose human health risks

The possibility of metal-based nanoparticles (NPs) being released into agricultural soils via sewage systems has raised widespread concern about their negative effects on crop plants, soils, and potential risks to human health via the food chain. The objectives of this study were to (i) determine the effect of CuO NPs in irrigation water on plant growth and Cu accumulation in a rice-soil system using continuous sub-irrigation with treated wastewater (CSI), and (ii) assess the Cu exposure and potential health risk associated with rice consumption. CuO NPs were examined in treated municipal wastewater (TWW) at environmentally acceptable concentrations (0, 0.02, 0.2, and 2.0 mg Cu L^-1), allowing for effluent discharge and/or crop irrigation reuse. Low CuO NP concentrations in TWW had no adverse effect on plant growth, yield, or grain quality. Cu accumulation significantly increased in various parts of rice plants and paddy soils at 2.0 mg Cu L^-1. CuO NPs had no discernible effect on rice plants when compared to CuSO₄ at 0.2 mg Cu L^-1. The estimated daily intake of Cu derived from inadvertent consumption of Cu-contaminated rice (by CuO NPs in TWW) for young children aged 0-6 years exceeded the oral reference dose for toxicity. Overall, we found no acute toxicity of CuO NPs in TWW to rice plants, but significant Cu accumulation in grains. This implies that there is a high risk of human health problems associated with rice that was intensively irrigated with TWW containing CuO NPs.

Dietary Antioxidant Curcumin Mitigates CuO Nanoparticle-Induced Cytotoxicity through the Oxidative Stress Pathway in Human Placental Cells

The placenta is an important organ that maintains a healthy pregnancy by transporting nutrients to the fetus and removing waste from the fetus. It also acts as a barrier to protect the fetus from hazardous materials. Recent studies have indicated that nanoparticles (NPs) can cross the placental barrier and pose a health risk to the developing fetus. The high production and widespread application of copper oxide (CuO) NPs may lead to higher exposure to humans, raising concerns of health hazards, especially in vulnerable life stages, e.g., pregnancy. Oxidative stress plays a crucial role in the pathogenesis of adverse pregnancy outcomes. Due to its strong antioxidant activity, dietary curcumin can act as a therapeutic agent for adverse pregnancy. There is limited knowledge on the hazardous effects of CuO NPs during pregnancy and their mitigation by curcumin. This study aimed to investigate the preventive effect of curcumin against CuO NP-induced toxicity in human placental (BeWo) cells. CuO NPs were synthesized by a facile hydrothermal process and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence techniques. We observed that curcumin did not induce toxicity in BeWo cells (1-100 µg/mL for 24 h), whereas CuO NPs decreased the cell viability dose-dependently (5-200 µg/mL for 24 h). Interestingly, CuO NP-induced cytotoxicity was effectively mitigated by curcumin co-exposure. The apoptosis data also exhibited that CuO NPs modulate the expression of several genes (p53, bax, bcl-2, casp3, and casp9), the activity of enzymes (caspase-3 and -9), and mitochondrial membrane potential loss, which was successfully reverted by co-treatment with curcumin. The mechanistic study suggested that CuO-induced reactive oxygen species generation, lipid peroxidation, and higher levels of hydrogen peroxide were significantly alleviated by curcumin co-exposure. Moreover, glutathione depletion and the lower activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, and catalase) were effectively mitigated by curcumin. We believe this is the first report exhibiting that CuO-induced toxicity in BeWo cells can be effectively alleviated by curcumin. The pharmacological potential of dietary curcumin in NP-induced toxicity during pregnancy warrants further investigation.

Latent Benefits and Toxicity Risks Transmission Chain of High Dietary Copper along the Livestock-Environment-Plant-Human Health Axis and Microbial Homeostasis: A Review

The extensive use of high-concentration copper (Cu) in feed additives, fertilizers, pesticides, and nanoparticles (NPs) inevitably causes significant pollution in the ecological environment. This type of chain pollution begins with animal husbandry: first, Cu accumulation in animals poisons them; second, high Cu enters the soil and water sources with the feces and urine to cause toxicity, which may further lead to crop and plant pollution; third, this process ultimately endangers human health through consumption of livestock products, aquatic foods, plants, and even drinking water. High Cu potentially alters the antibiotic resistance of soil and water sources and further aggravates human disease risks. Thus, it is necessary to formulate reasonable Cu emission regulations because the benefits of Cu for livestock and plants cannot be ignored. The present review evaluates the potential hazards and benefits of high Cu in livestock, the environment, the plant industry, and human health. We also discuss aspects related to bacterial and fungal resistance and homeostasis and perspectives on the application of Cu-NPs and microbial high-Cu removal technology to reduce the spread of toxicity risks to humans.

Foliar Application of Copper Oxide Nanoparticles Increases the Photosynthetic Efficiency and Antioxidant Activity in Brassica juncea

In the last few decades, use of copper oxide nanoparticles (CuO NPs) has been increased significantly that eventually included as a growth stimulator. This makes it essential to examine their impact on several plants. In the study detailed here, we investigated the effects of CuO NPs on the growth, physiological efficiency, biochemical assays, and antioxidant system in the mustard plant. Varying concentrations (0, 2, 4, 8, and 16 mg/L) of CuO NPs were applied at 25 days after sowing (DAS), and sampling took place at 30 and 45 DAS. The results indicate that CuO NPs-treated plants registered an increase in the growth and biomass over their respective control. Among different concentrations of CuO NPs (0, 2, 4, 8, and 16 mg/L), 8 mg/L proved to be the optimum foliar spray treatment and increase the chlorophyll content, net photosynthetic rate, leaf proline content, and antioxidant enzymes activity. We concluded that CuO NPs interact with meristematic cells triggering biochemical pathways conductive to an enhancement of the growth attributes. Further studies are needed to investigate the mechanisms of CuO NPs in mustard.

Impact of engineered nanomaterials on rice (Oryza sativa L.): A critical review of current knowledge

After use, a large number of engineered materials (ENMs) are directly or indirectly released into the environment. This may threaten the agricultural ecosystem, especially with crops under high demand for irrigation water, such as rice (Oryza sativa L.), a crop that feeds nearly half of the world's population. However, consistent and detailed information on the effects of nanoparticles in rice is limited. This review is a systematic exploration of the effects of ENMs on rice, with a critical evaluation of the mechanisms reported in the literature by which different nanomaterials cause toxicity in rice. The physiological and biochemical effects engendered by the nanoparticles are highlighted, focusing on rice growth and development, ENMs uptake and translocation, gene expression changes, enzyme activity modifications, and secondary metabolite alterations.

Fate, bioaccumulation and toxicity of engineered nanomaterials in plants: Current challenges and future prospects

The main focus of this review is to discuss the current advancement in nano-metallic caused phytotoxicity on living organisms and current challenges in crops. Nanostructured materials provide new tools in agriculture to boost sustainable food production, but the main concern is that large-scale production and release of nanomaterials (NMs) into the ecosystem is a rising threat to the surrounding environment that is an urgent challenge to be addressed. The usage of NMs directly influences the transport pathways within plants, which directly relates to their stimulatory/ inhibitory effects. Because of the unregulated nanoparticles (NMs) exposure to soil, they are adsorbed at the root surface, followed by uptake and inter/intracellular mobility within the plant tissue, while the aerial exposure is taken up by foliage, mostly through cuticles, hydathodes, stigma, stomata, and trichomes, but the actual mode of NMs absorption into plants is still unclear. NMs-plant interactions may have stimulatory or inhibitory effects throughout their life cycle depending on their composition, size, concentration, and plant species. Although many publications on NMs interactions with plants have been reported, the knowledge on their uptake, translocation, and bioaccumulation is still a question to be addressed by the scientific community. One of the critical aspects that must be discovered and understood is detecting NMs in soil and the uptake mechanism in plants. Therefore, the nanopollution in plants has yet to be completely understood regarding its impact on plant health, making it yet another artificial environmental influence of unknown long-term consequences. The present review summarizes the uptake, translocation, and bioaccumulation of NMs in plants, focusing on their inhibitory effects and mechanisms involved within plants.

Nanotechnology in Plant Metabolite Improvement and in Animal Welfare

Plant tissue culture plays an important role in plant biotechnology due to its potential for massive production of improved crop varieties and high yield of important secondary metabolites. Several efforts have been made to ameliorate the effectiveness and production of plant tissue culture, using biotic and abiotic factors. Nowadays, the addition of nanoparticles as elicitors has, for instance, gained worldwide interest because of its success in microbial decontamination and enhancement of secondary metabolites. Nanoparticles are entities in the nanometric dimension range: they possess unique physicochemical properties. Among all nanoparticles, silver-nanoparticles (AgNPs) are well-known for their antimicrobial and hormetic effects, which in appropriate doses, led to the improvement of plant biomass as well as secondary metabolite accumulation. This review is focused on the evaluation of the integration of nanotechnology with plant tissue culture. The highlight is especially conveyed on secondary metabolite enhancement, effects on plant growth and biomass accumulation as well as their possible mechanism of action. In addition, some perspectives of the use of nanomaterials as potential therapeutic agents are also discussed. Thus, the information provided will be a good tool for future research in plant improvement and the large-scale production of important secondary metabolites. Elicitation of silver-nanoparticles, as well as nanomaterials, function as therapeutic agents for animal well-being is expected to play a major role in the process. However, nanosized supramolecular aggregates have received an increased resonance also in other fields of application such as animal welfare. Therefore, the concluding section of this contribution is dedicated to the description and possible potential and usage of different nanoparticles that have been the object of work and expertise also in our laboratories.

The combined toxicity and mechanism of multi-walled carbon nanotubes and nano zinc oxide toward the cabbage

The natural environment is a complex system, and there is never only one kind of nanomaterial entering the environment. However, many studies only considered the plant toxicity of one kind of nanomaterial and do not consider the influence of two or more kinds of nanomaterials on plant toxicity. Multi-walled carbon nanotubes (MWCNTs) and zinc oxide nanoparticles (ZnO NPs) are two common and widely used nanomaterials in water environment, so these two kinds of nanomaterials were chosen to explore the effects of their combined toxicity on cabbage. This study investigated the toxicity of MWCNTs combined with ZnO NPs on cabbage by measuring the length of roots and stems, chlorophyll content, oxidative stress, antioxidant enzyme activity, metal element content, and root scanning electron microscopy. The toxicity of single MWCNTs toward cabbage was attributed to direct oxidative damage, while the toxicity of single ZnO NPs toward cabbage was due to the high level of zinc concentration. Moreover, ZnO NPs (10 mg/L) ameliorated MWCNTs toxicity toward cabbage by improving the activity of antioxidant enzymes. ZnO NPs (50 and 100 mg/L) because of the high content of zinc disrupted the balance of other metals in the plant and increased the toxicity of MWCNTs. In conclusion, the combined toxicity of different concentrations and types of nanomaterials should be considered for a more accurate assessment of environmental risks.

Impact of CuO nanoparticles on maize: Comparison with CuO bulk particles with special reference to oxidative stress damages and antioxidant defense status

The present study aimed to systematically investigate the particle size effects of copper (II) oxide [CuO nanoparticles (<50 nm) and CuO bulk particles (<10 μm)] on maize (Zea mays L.). Bioaccumulation of Cu, in vivo ROS generation, membrane damage, transcriptional modulation of antioxidant genes, cellular redox status of glutathione and ascorbate pool, expression patterns of COPPER TRANSPORTER 4 and stress responsive miRNAs (miR398a, miR171b, miR159f-3p) with their targets were investigated for better understanding of the underlying mechanisms and the extent of CuO nanoparticles and CuO bulk particles induced oxidative stress damages. More restricted seedling growth, comparatively higher membrane injury, marked decline in the levels of chlorophylls and carotenoids and severe oxidative burst were evident in CuO bulk particles challenged leaves. Dihydroethidium and CM-H2DCFDA staining further supported elevated reactive oxygen species generation in CuO bulk particles stressed roots. CuO bulk particles exposed seedlings accumulated much higher amount of Cu in roots as compared to CuO nanoparticles stressed plants with low root-to-shoot Cu translocation. Moderately high GR expression with maintenance of a steady GSH-GSSG ratio in CuO nanoparticles challenged leaves might be accountable for their rather improved performance under stressed condition. miR171b-mediated enhanced expression of SCARECROW 6 might participate in the marked decline of chlorophyll content in CuO bulk particles exposed leaves. Ineffective recycling of AsA pool is another decisive feature of inadequate performance of CuO bulk particles stressed seedlings in combating oxidative stress damages. Taken together, our findings revealed that toxicity of CuO bulk particles was higher than CuO nanoparticles and the adverse effects of CuO bulk particles on maize seedlings might be due to higher Cu ions dissolution.

The severe toxicity of CuO nanoparticles to the photosynthesis of the prokaryotic algae Arthrospira sp

This research first verified that prokaryotic algae are more sensitive to toxicity of CuO nanoparticles (CuO NPs) than eukaryotic algae and that CuO NPs damaged photosynthesis of prokaryotic algae (Arthrospira sp.) but had no effect on respiration. The Cu²⁺ released by CuO NPs caused a bending deformation of the thylakoid, which was an important cause of the decline in photosynthetic capacity. In addition, the D1 protein was the most susceptible site to CuO NPs. The degradation of D1 protein reduced photosynthetic electron transport, which enhanced the excess excitation energy to cause the accumulation of reactive oxygen species (ROS) to further result in oxidative stress on algae. Dissolved organic matter (DOM) increased the toxicity of CuO NPs to photosynthesis of Arthrospira sp. The damage of photosynthesis caused by CuO NPs is an important reason why CuO NPs have a serious toxicity to algae.

Mobility of arsenic in the growth media of rice plants (Oryza sativa subsp. japonica. 'Koshihikari') with exposure to copper oxide nanoparticles in a life-cycle greenhouse study

The increasing arsenic (As) concentration in agriculture media poses increasing risks to both environment and human health. Arsenic mobility determines its bioavailability and entry into the food chain. Nanoparticle application may help to control As mobility in crop cultivation media, and thus decreasing As bioavailability for plants. This research studied the adsorption kinetics of As(V) on copper oxide nanoparticles (nCuO) and nCuO dissolution in a hydroponic solution, and the effects of nCuO on As mobility in a greenhouse system exposed to As(V) addition of 10 mg/kg and nCuO at 0.1-100 mg/L for a life-cycle growth of rice. Arsenic adsorption was dependent on both the total mass and the concentration of nCuO as well as the initial concentration of As(V), while nCuO dissolution was mainly dependent on nCuO concentration regardless of As(V). Arsenic in the simulated paddy was quickly mobilized from soil to aqueous phase during week 1, and further interacted with components in water phase, sediment-water interfacial transition and rice plants. Copper (Cu) and As speciation in the soil were observed by X-Ray Absorption Near Edge Spectrometry. Dissolved Cu was complexed with organic ligands. As(V) was adsorbed to kaolinite, or reduced to As(III) and adsorbed to ferrihydrite. Percent As removal from water phase in the growth container was determined by both nCuO application and As(V) initial concentration. Based on our previous finding that As accumulation in rice grains was significantly decreased by nCuO at 50 mg/L and the results of this study on As adsorption capacity of nCuO and As removal from water due to nCuO application, nCuO at 50 mg/L was proposed to be an appropriate application in rice paddy to immobilize As. Further research is needed in actual agriculture to verify the appropriate nCuO application and get an integrated beneficial effect for rice plants and humans.

Effects of copper oxide nanoparticles on germination of Sesbania virgata (FABACEAE) plants

Nanotechnology is a field that, over the years, has been growing in several research areas, such as medicine, agriculture and cosmetics, among others. As a result, there is a continuous increase in the production, use and disposal of these materials in the environment. The behaviour and (bio) activity of these materials in the atmosphere, water and soil are not fully studied. Therefore, it is necessary to carry out an analysis of the risks of contamination, as well as the possible effects and impacts of nanoparticles (NPs) on the ecosystem. In an attempt to investigate these effects on plants, the present study aimed to investigate the impact of copper oxide nanoparticles (CuO NPs) on the seed germination process of Sesbania virgata. For this, the Sesbania virgata seeds were subjected to different concentration of CuO NPs (0, 100, 200, 300 and 400 mgL-1) and their germination and development were monitored by optical analysis (thermography and chlorophyll a fluorescence). The results show that the CuO NPs induced a reduction on the maximum emission of chlorophyll a, which was concentration-dependent. The data also showed that CuO NPs promoted an increase in the energy dissipated by non-photochemical pathways and the surface temperature of the seeds. Additionally, our findings revealed that CuO NPs caused a root growth inhibition. In summary, the present study demonstrates, for the first time, that CuO NPs can negatively affect the physiological status and development of the S. virgata plant, by altering the efficiency of the functioning of photosystem II in its initial developmental stage, depending on the concentration of CuO NPs.

Efficacy Assessment of Biosynthesized Copper Oxide Nanoparticles (CuO-NPs) on Stored Grain Insects and Their Impacts on Morphological and Physiological Traits of Wheat (Triticum aestivum L.) Plant

Herein, CuO-NPs were fabricated by harnessing metabolites of Aspergillus niger strain (G3-1) and characterized using UV-vis spectroscopy, XRD, TEM, SEM-EDX, FT-IR, and XPS. Spherical, crystallographic CuO-NPs were synthesized in sizes ranging from 14.0 to 47.4 nm, as indicated by TEM and XRD. EDX and XPS confirmed the presence of Cu and O with weight percentages of 62.96% and 22.93%, respectively, at varied bending energies. FT-IR spectra identified functional groups of metabolites that could act as reducing, capping, and stabilizing agents to the CuO-NPs. The insecticidal activity of CuO-NPs against wheat grain insects Sitophilus granarius and Rhyzopertha dominica was dose- and time-dependent. The mortality percentages due to NP treatment were 55-94.4% (S. granarius) and 70-90% (R. dominica). A botanical experiment was done in a randomized block design. Low CuO-NP concentration (50 ppm) caused significant increases in growth characteristics (shoot and root length, fresh and dry weight of shoot and root, and leaves number), photosynthetic pigments (total chlorophylls and carotenoids), and antioxidant enzymes of wheat plants. There was no significant change in carbohydrate or protein content. The use of CuO-NPs is a promising tool to control grain insects and enhance wheat growth performance.

Toxicological effects of different-sized Co-Fe (CoFe2O4) nanoparticles on Lepidium sativum L.: towards better understanding of nanophytotoxicity

Due to their widespread therapeutic and agricultural applicability and usefulness in removing metals and metalloids from water, cobalt ferrite nanoparticles (NPs) are currently receiving increasing attention from researchers. However, their potential phytotoxicity is still poorly understood. Thus, the aim of the current study was to assess the effects of synthesized cobalt ferrite (CoFe₂O₄) NPs on biological (morphological, physiological, and biochemical) parameters of edible plant garden-cress (Lepidium sativum L.), depending on particle size and concentrations. In this study, physical characteristics of cobalt ferrite NPs were determined. Increased total content of Co and Fe in L. sativum tissues and their transfer from roots to above-ground parts of seedlings, which depended on the size of NP (15 < 5 < 1.65 nm), indicated that plants had been exposed to Co ferrite NPs. The relative growth of roots, biomass of roots and above-ground parts of seedlings, amounts of chlorophylls a and b, carotenoids, and malondialdehyde (MDA) were determined. The dependence of the tested garden-cress parameters on the size and concentrations of NPs was revealed. Our data showed that the content of MDA in test plants in some cases increased up to 2.5 folds in comparison to control. The increase of the content of chlorophyll b pigment and MDA in test plants is an appropriate indicator of the impact of cobalt ferrite NPs. The findings of our study into toxicological effects of Co-Fe (CoFe₂O₄) NPs on L. sativum are expected to deepen the knowledge of the nanophytotoxicity of ferromagnetic NPs and their potential application in biomedicine and agriculture.

Biostimulation and toxicity: The magnitude of the impact of nanomaterials in microorganisms and plants

Background

Biostimulation and toxicity constitute the continuous response spectrum of a biological organism against physicochemical or biological factors. Among the environmental agents capable of inducing biostimulation or toxicity are nanomaterials. On the < 100 nm scale, nanomaterials impose both physical effects resulting from the core’s and corona’s surface properties, and chemical effects related to the core’s composition and the corona’s functional groups.

Aim of Review

The purpose of this review is to describe the impact of nanomaterials on microorganisms and plants, considering two of the most studied physical and chemical properties: size and concentration.

Key Scientific Concepts of Review

Using a graphical analysis, the presence of a continuous biostimulation-toxicity spectrum is shown considering different biological responses. In microorganisms, the results showed high susceptibility to nanomaterials. Simultaneously, in plants, a hormetic response was found related to nanomaterials concentration and, in a few cases, a positive response in the smaller nanomaterials when these were applied at a higher level. With the above, it is concluded that: (1) microorganisms are more susceptible to nanomaterials than plants, (2) practically all nanomaterials seem to induce responses from biostimulation to toxicity in plants, and (3) the kind of response observed will depend in a complex way on the nanomateriaĺs physical and chemical characteristics, of the biological species with which they interact, and of the form and route of application and on the nature of the medium -soil, soil pore water, and biological surfaces- where the interaction occurs.

Biodegradable Antimicrobial Food Packaging: Trends and Perspectives

This review presents a perspective on the research trends and solutions from recent years in the domain of antimicrobial packaging materials. The antibacterial, antifungal, and antioxidant activities can be induced by the main polymer used for packaging or by addition of various components from natural agents (bacteriocins, essential oils, natural extracts, etc.) to synthetic agents, both organic and inorganic (Ag, ZnO, TiO2 nanoparticles, synthetic antibiotics etc.). The general trend for the packaging evolution is from the inert and polluting plastic waste to the antimicrobial active, biodegradable or edible, biopolymer film packaging. Like in many domains this transition is an evolution rather than a revolution, and changes are coming in small steps. Changing the public perception and industry focus on the antimicrobial packaging solutions will enhance the shelf life and provide healthier food, thus diminishing the waste of agricultural resources, but will also reduce the plastic pollution generated by humankind as most new polymers used for packaging are from renewable sources and are biodegradable. Polysaccharides (like chitosan, cellulose and derivatives, starch etc.), lipids and proteins (from vegetal or animal origin), and some other specific biopolymers (like polylactic acid or polyvinyl alcohol) have been used as single component or in blends to obtain antimicrobial packaging materials. Where the package's antimicrobial and antioxidant activities need a larger spectrum or a boost, certain active substances are embedded, encapsulated, coated, grafted into or onto the polymeric film. This review tries to cover the latest updates on the antimicrobial packaging, edible or not, using as support traditional and new polymers, with emphasis on natural compounds.

Nanoparticles in Agroindustry: Applications, Toxicity, Challenges, and Trends

Nanotechnology is a tool that in the last decade has demonstrated multiple applications in several sectors, including agroindustry. There has been an advance in the development of nanoparticulated systems to be used as fertilizers, pesticides, herbicides, sensors, and quality stimulants, among other applications. The nanoencapsulation process not only protects the active ingredient but also can affect the diffusion, interaction, and activity. It is important to evaluate the negative aspects of the use of nanoparticles (NPs) in agriculture. Given the high impact of the nanoparticulated systems in the agro-industrial field, this review aims to address the effects of various nanomaterials on the morphology, metabolomics, and genetic modification of several crops.

Multifunctional molybdenum disulfide-copper nanocomposite that enhances the antibacterial activity, promotes rice growth and induces rice resistance

Molybdenum disulfide sheets loaded with copper nanoparticles (MoS₂-CuNPs) was prepared and its antibacterial activity against phytopathogen Xanthomonas oryzae pv. oryzae (Xoo) was investigated in vitro and in vivo for the first time. In a 2 h co-incubation, MoS₂-CuNPs exhibited 19.2 times higher antibacterial activity against Xoo cells than a commercial copper bactericide (Kocide 3000). In the detached leaf experiment, the disease severity decreased from 86.25 % to 7.5 % in the MoS₂-CuNPs treated rice leaves. The results further demonstrated that foliar application of MoS₂-CuNPs could form a protective film and increase the density of trichome on the surface of rice leaves, finally prevent the infection of Xoo cells. This was probably due to the synergistic effect of MoS₂-CuNPs. Additionally, foliar application of MoS₂-CuNPs (4-32 μg/mL) increased obviously the content of Mo and chlorophyll (up 30.85 %), and then improved the growth of rice seedlings. Furthermore, the obtained MoS₂-CuNPs could activate the activities of the antioxidant enzymes in rice, indicating higher resistance of rice under abiotic/biotic stresses. The multifunctional MoS₂-CuNPs with superior antibacterial activity provided a promising alternative to the traditional antibacterial agents and had great potential in plant protection.