Nickel Oxide Nanoparticles Improve Soybean Yield and Enhance Nitrogen Assimilation.

Nickel (Ni) is a trace element beneficial for plant growth and development and could improve crop yield by stimulating urea decomposition and nitrogen-fixing enzyme activity. A full life cycle study was conducted to compare the long-term effects of soil-applied NiO nanoparticles (n-NiO), NiO bulk (b-NiO), and NiSO4 at 10-200 mg kg-1 on plant growth and nutritional content of soybean. n-NiO at 50 mg kg-1 significantly promoted the seed yield by 39%. Only 50 mg kg-1 n-NiO promoted total fatty acid content and starch content by 28 and 19%, respectively. The increased yield and nutrition could be attributed to the regulatory effects of n-NiO, including photosynthesis, mineral homeostasis, phytohormone, and nitrogen metabolism. Furthermore, n-NiO maintained a Ni2+ supply for more extended periods than NiSO4, reducing potential phytotoxicity concerns. Single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) for the first time confirmed that the majority of the Ni in seeds is in ionic form, with only 28-34% as n-NiO. These findings deepen our understanding of the potential of nanoscale and non-nanoscale Ni to accumulate and translocate in soybean, as well as the long-term fate of these materials in agricultural soils as a strategy for nanoenabled agriculture.

Influence of calcium and magnesium elimination on plant biomass and secondary metabolites of Stevia rebaudiana Bertoni.

This study reports the increment in the secondary metabolites in Stevia rebaudiana plant after exposure to the elimination of Ca and Mg from Murashige and Skoog culture medium. The effect of nutrient stress on regenerants of S. rebaudiana is measured, which reveals significantly enhanced growth parameters, steviol glycosides (SGs) content, and nonenzymatic antioxidants; total phenolic content, total flavonoid content, total antioxidant capacity, total reducing power, and DPPH-free radical scavenging activity as compared with the control treatment. However, significantly highest amounts are obtained in a medium with only Ca deficiency. The amount of rebaudioside A (Reb A) and stevioside (ST) obtained in the case of Ca-deficient medium is 4.08 and 0.69%, respectively. It is followed by the results obtained from both Ca- and Mg-deprived medium [Reb A (3.23%) and ST (0.52%)] and the lowest values are obtained from medium lacking Mg only [Reb A (2.60%) and ST (0.40%)]. The most probable adaptation mechanism might be the production of reactive oxygen species by nutrients' stress, which results in secondary metabolites production as defensive moieties to overcome stress situation. This effective protocol needs to be refined to apply on an industrial scale in bioreactors for increasing quantities of commercially important pharmaceutical compounds.

The combination of nanotechnology and potassium: applications in agriculture.

Potassium fertilizer is indispensable for ensuring crop production, which in turn supports global food supply and safe farming practices. Potassium resources are primarily located in the Northern Hemisphere, leading to a current shortage of affordable potash and severe soil deficiencies in certain regions of the Southern Hemisphere. There is a shift away from mined salts in favor of locally available potassium resources. Utilizing potassium-rich silicates, for instance, could be a viable option to address this situation. The imperative of enhancing crop productivity and quality necessitates either increasing potassium availability or utilizing potassium more efficiently. Geneticists may find the development of plants that use potassium more effectively to be a valuable pursuit. Nanomaterials are increasingly becoming part of people's professional lives as a novel material category. This technology is gradually finding applications in agriculture to boost crop yields while reducing environmental pollution. This paper reviews the applications of common potassium-containing materials, explores the effects and mechanisms of nano-fertilizers on plants, and offers insights into future applications of nano-potassium fertilizers in agriculture. All in all, the application of nanotechnology in the production and utilization of potassium fertilizers is both necessary and effective. However, there are still many gaps in the current field of nano-potassium fertilizer application that require further research. It is hoped that this review can serve as a valuable reference for researchers working in this field.

Co-exposure to tire wear particles and nickel inhibits mung bean yield by reducing nutrient uptake.

Soil and terrestrial contamination with microplastics and nanoplastics has been discussed extensively, while tire wear particles (TWPs) have been largely overlooked. We investigated the root-surface interactions and growth response of mung bean (Vigna radiata L.) plants exposed to tire wear particles (TWPs) (0.05, 0.1, and 0.25% w/w) and nickel sulfate (50 and 100 mg kg-1 NiSO4) alone and in co-exposure scenarios for the full life cycle (105 days) under soil conditions. The results show that TWPs adhered to the root surface and reduced the water and nutrient uptake by the plant, particularly at higher concentrations of TWPs (0.25% w/w), without any observed organic contaminant accumulation in the root tissue. TWPs alone at 0.01, 0.1, and 0.25% (w/w) decreased mung bean yield by 11, 28, and 52%, respectively. Co-exposure to TWPs at 0.01, 0.1 and 0.25% w/w with 100 mg kg-1 NiSO4 decreased yield by 73, 79 and 88%, respectively. However, co-exposure to TWPs at 0.01 and 0.1% w/w with 50 mg kg-1 NiSO4 enhanced the yield by 32% and 7%, respectively. These changes in yield and nutritional aspects appear to be linked to Ni's regulatory influence on mineral homeostasis. Moreover, exposure to NiSO4 at 100 mg kg-1 increased Ni uptake in the root, shoot, and grain by 9, 26, and 20-fold, respectively as compared to the unamended control; this corresponded to increased antioxidant enzyme activity (10-127%) as compared to the control. TWPs caused blockages, significantly reducing plant yield and altering nutrient dynamics, highlighting emerging risks to plant health.

Cryptic footprint of thallium in soil-plant systems; A review.

The current review highlights the complex behavior of thallium (Tl) in soil and plant systems, offering insight into its hazardous characteristics and far-reaching implications. The research investigates the many sources of Tl, from its natural existence in the earth crust to its increased release through anthropogenic activities such as industrial operations and mining. Soil emerges as a significant reservoir of Tl, with diverse physicochemical variables influencing bioavailability and entrance into the food chain, notably in Brassicaceae family members. Additionally, the study highlights a critical knowledge gap concerning Tl influence on legumes (e.g., soybean), underlining the pressing demand for additional studies in this crucial sector. Despite the importance of leguminous crops in the world food supply and soil fertility, the possible impacts of Tl on these crops have received little attention. As we traverse the ecological complexity of Tl, this review advocates the collaborative research efforts to eliminate crucial gaps and provide solutions for reducing Tl detrimental impacts on soil and plant systems. This effort intends to pave the path for sustainable agricultural practices by emphasizing the creation of Tl-tolerant legume varieties and revealing the complicated dynamics of Tl-plant interactions, assuring the long-term durability of our food systems against the danger of Tl toxicity.

Integrating nanotechnology with plant microbiome for next-generation crop health.

Nanotechnology has enormous potential for sustainable agriculture, such as improving nutrient use efficiency, plant health, and food production. Nanoscale modulation of the plant-associated microbiota offers an additional valuable opportunity to increase global crop production and ensure future food and nutrient security. Nanomaterials (NMs) applied to agricultural crops can impact plant and soil microbiota, which offers valuable services to host plants, including the acquisition of nutrients, abiotic stress tolerance, and disease suppression. Dissecting the complex interactions between NMs and plants by integrating multi-omic approaches is providing new insights into how NMs can activate host responses and functionality as well as influence native microbial communities. Such nexus and moving beyond descriptive microbiome studies to hypothesis-driven research will foster microbiome engineering and open up opportunities for the development of synthetic microbial communities to provide agronomic solutions. Herein, we first summarize the significant role of NMs and the plant microbiome in crop productivity and then focus on NMs effects on plant-associated microbiota. We outline three urgent priority research areas and call for a transdisciplinary collaborative approach, involving plant scientists, soil scientists, environmental scientists, ecologists, microbiologists, taxonomists, chemists, physicists, and stakeholders, to advance nano-microbiome research. Detailed understanding of the nanomaterial-plant-microbiome interactions and the mechanisms underlying NMs-mediated shifts in the microbiome assembly and functions may help to exploit the services of both nano-objects and microbiota for next-generation crop health.

Unraveling the roles of modified nanomaterials in nano enabled agriculture.

Nanotechnology has emerged as a key empowering technology for agriculture production due to its higher efficiency and accurate target delivery. However, the sustainable and effective application of nanotechnology requires nanomaterials (NMs) to have higher stability and less aggregation/coagulation at the reaction sites. This can ideally be achieved by modifying NMs with some surfactants or capping agents to ensure higher efficiency. These modified nanomaterials (MNMs) stabilize the interface where NMs interact with their medium of preparation and showed a significant improvement in mobility, reactivity, and controlled release of active ingredients for nano-enabled agriculture. Several environmental factors (e.g., pH, organic matter and the oxidation-reduction potential) could alter the interaction of MNMs with agricultural plants. Firstly, this novel review article introduces production technologies and a few frequently used modification agents in synthesizing MNMs. Next, we critically elaborate the leveraging progress in the modified nano-enabled agronomy and unveil their phytoremediation potential. Lastly, we propose a framework to overcome current challenges and develop a strategy for safe, effective and acceptable applications of MNMs in nano-enabled agriculture. However, the long-term effectiveness and reactivity of MNMs should be investigated to assess their technology effectiveness and optimize the process design to draw definite conclusions.

Lithium-induced alterations in soybean nodulation and nitrogen fixation through multifunctional mechanisms.

The increasing footprints of lithium (Li) in agroecosystems combined with limited recycling options have raised uncertain consequences for important crops. Nitrogen (N2)-fixation by legumes is an important biological response process, but the cause and effect of Li exposure on plant root-nodule symbiosis and biological N2-fixation (BNF) potential are still unclear. Soybean as a model plant was exposed to Li at low (25 mg kg-1), medium (50 mg kg-1), and high (100 mg kg-1) concentrations. We found that soybean growth and nodulation capacity had a concentration-dependent response to Li. Li at 100 mg kg-1 reduced the nodule numbers, weight, and BNF potential of soybean in comparison to the low and medium levels. Significant shift in soybean growth and BNF after exposure to Li were associated with alteration in the nodule metabolic pathways involved in nitrogen uptake and metabolism (urea, glutamine and glutamate). Importantly, poor soybean nodulation after high Li exposure was due in part to a decreased abundance of bacterium Ensifer in the nodule bacterial community. Also, the dominant N2-fixing bacterium Ensifer was significantly correlated with carbon and nitrogen metabolic pathways. The findings of our study offer mechanistic insights into the environmental and biological impacts of Li on soybean root-nodule symbiosis and N2-acquisition and provide a pathway to develop strategies to mitigate the challenges posed by Li in agroecosystems.

Effects of two Mn-based nanomaterials on soybean antioxidant system and mineral element homeostasis.

Since less attention has been paid to the physiological effects of manganese-based nanomaterials (Mn-based NMs) on plants, it is necessary to explore the application of Mn-based NMs in improving crop yield and the concentration range of Mn-based NMs that produce toxicity. The results showed that soil application of 100 mg/kg manganese oxide (MnO2) and manganese tetroxide (Mn3O4) NMs could increase the shoot height of soybean by 51.8% and 31.8%, respectively, compared with the control. In addition, 100 mg/kg MnO2 NMs increased catalase (CAT) activity in roots by 62.2%, and 50 mg/kg Mn3O4 NMs increased CAT activity in roots by 200%, thereby increasing the stress resistance of soybean. However, at the highest concentration of 500 mg/kg, Mn-based NMs increased the Mn content in soybean extremely so that the absorption of mineral elements such as potassium, phosphorus, and calcium in the root was inhibited. This research lays the foundation for the safe application of Mn-based NMs in agriculture, benefiting the development of nanotechnology and agriculture globally.

Application and mechanisms of metal-based nanoparticles in the control of bacterial and fungal crop diseases.

Nanotechnology is a young branch of the discipline generated by nanomaterials. Its development has greatly contributed to technological progress and product innovation in the field of agriculture. The antimicrobial properties of nanoparticles (NPs) can be used to develop nanopesticides for plant protection. Plant diseases caused by bacterial and fungal infestations are the main types of crop diseases. Once infected, they will seriously threaten crop growth, reduce yield and quality, and affect food safety, posing a health risk to humans. We reviewed the application of metal-based nanoparticles in inhibiting plant pathogenic bacteria and fungi, and discuss the antibacterial mechanisms of metal-based nanoparticles from two aspects: the direct interaction between nanoparticles and pathogens, and the indirect effects of inducing plant resilience to disease. © 2022 Society of Chemical Industry.

Phosphorus-based nanomaterials as a potential phosphate fertilizer for sustainable agricultural development.

Phosphorus-based nanomaterials (PNMs) have been reported to have substantial promise for promoting plant growth, improving plant tolerance mechanisms, and increasing resistance to pathogenic organisms. Recent scientific investigation has demonstrated that utilizing PNMs can enhance plant physiological growth, photosynthetic pigments, antioxidant system, metabolism, nutrient absorption, rhizosphere secretion, and soil nutrients activation. Previous research on PNMs mostly concentrated on calcium phosphate, zeolite, and chitosan, with little systematic summarization, demanding a thorough evaluation of PNMs' broader uses. In our current review article, we address the knowledge gap by classifying PNMs according to green synthesis methods and the valence state of phosphorus while elucidating the underlying mechanisms through which these PNMs facilitate plant growth. In addition, we also targeted some strategies to improve the bioavailability of PNMs, offering valuable insights for the future design and safe implementation of PNMs in agricultural practices.

Iron-based nanomaterials reduce cadmium toxicity in rice (Oryza sativa L.) by modulating phytohormones, phytochelatin, cadmium transport genes and iron plaque formation.

Rice is known to accumulate cadmium (Cd) in its grains, causing a severe threat to billions of people worldwide. The possible phytotoxicity and mechanism of 50-200 mg/L hydroxyapatite NPs (nHA), iron oxide NPs (nFe2O3) or nano zero valent iron (nZVI) co-exposed with Cd (100 µM) in rice seedlings were investigated. Three types of nanoparticles significantly reduced the bioaccumulation of Cd in rice shoots by 16-63%, with nZVI showing the greatest effect, followed by nHA and nFe2O3. A decrease in Cd content in the roots was observed only in the nZVI treatment, with values ranging from 8 to 19%. Correspondingly, nZVI showed the best results in promoting plant growth, increasing rice plant height, shoot and root biomass by 13%, 29% and 42%. In vitro studies showed that nZVI reduced the content of Cd in the solution by 20-52% through adsorption, which might have contributed to the immobilization of Cd in root. Importantly, the nZVI treatment resulted in 267% more iron plaques on the root surface, which acted as a barrier to hinder the entry of Cd. Moreover, all three nanoparticles significantly reduced the oxidative stress induced by Cd by regulating phytohormones, phytochelatin, inorganic homeostasis and the expression of genes associated with Cd uptake and transport. Overall, this study elucidates for the first time the multiple complementing mechanisms for some nanoparticles to reduce Cd uptake and transport in rice and provides theoretical basis for applying nanoparticles for reducing Cd accumulation in edible plants.

Antagonistic impact on cadmium stress in alfalfa supplemented with nano-zinc oxide and biochar via upregulating metal detoxification.

Eco-toxicological estimation of cadmium induced damages by morpho-physiological and cellular response could be an insightful strategy to alleviate negative impact of Cd in agricultural crops. The current study revealed novel patterns of Cd-bioaccumulation and cellular mechanism opted by alfalfa to acquire Cd tolerance under various soil applied zinc oxide nanoparticles (nZnO) doses (0, 30, 60, 90 mg kg-1), combined with 2% biochar (BC). Herein, the potential impact of these soil amendments was justified by decreased Cd and increased Zn-bioaccumulation into roots by 38 % and 48 % and shoots by 51 % and 72 % respectively, with co-exposure of nZnO with BC. As, the transmission electron microscopy (TEM) and scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) ultrastructural observations confirmed that Cd-exposure induced stomatal closure, and caused damage to roots and leaves ultrastructure as compared to the control group. On the contrary, the damages to the above-mentioned traits were reversed by a higher nZnO dose, and the impact was further aggravated by adding BC along nZnO. Furthermore, higher nZnO and BC levels efficiently alleviated the Cd-mediated reductions in alfalfa biomass, antioxidant enzymatic response, and gaseous exchange traits than control. Overall, soil application of 90 mg kg-1 nZnO with BC (2 %) was impactful in averting Cd stress damages and ensuring better plant performance. Thereby, applying soil nZnO and BC emerge as promising green remediation techniques to enhance crop tolerance in Cd-polluted soil.

Interplay of higher plants with lithium pollution: Global trends, meta-analysis, and perspectives.

Lithium (Li) is gaining attention due to rapid rise in modern industries but their ultimate fingerprints on plants are not well established. Herein, we executed a meta-analysis of the existing recent literature investigating the impact of Li sources and levels on plant species under different growth conditions to understand the existing state of knowledge. Toxic effects of Li exposure in plants varies as a function of medium and interestingly, more negative responses are reported in hydroponic media as compared to soil and foliar application. Additionally, toxic effects of Li vary with Li source materials and LiCl more negatively affected plant development parameters such as plant germination (n = 48) and root biomass (n = 57) and recorded highly uptake in plants (n = 78), while LiNO3 has more negative effects on shoot biomass. The Li at <50 mg L-1 concentrations significantly influenced the plant physiological indicators including plant germination and root biomass, while 50-500 mg L-1 Li concentration influence the biochemical parameters. The dose-response relationship (EC50) ranges regarding the exposure medium of Li sources in plant species were observed 24.6-196.7 ppm respectively. The uptake potential of Li is dose-dependent and their translocation/bioaccumulation remains unknown. Future work should include full life cycle studies of the crops to elucidate the bioaccumulation of Li in edible tissues and to investigate possible trophic transfer of Li.

Modifying engineered nanomaterials to produce next generation agents for environmental remediation.

The application of pristine nanomaterials (PNMs) for environment remediation remains challenging due to inherently high potential for aggregation, low stability, sub-optimum efficiency, and non-uniformity in size and toxicity. Conversely, modified nanomaterials (MNMs) approaches have shown significant potential to enhance the technical and economic efficiency of conventional nanoscale remediation strategies by decreasing aggregation of nanomaterials by imparting electrostatic, electrosteric or steric repulsion between particles. Furthermore, the solubility enhancing agents in MNMs have been shown to increase metal bioavailability and accelerate the breakdown of pollutants. As such, it is imperative to modify nanomaterials for unlocking their full potential and expanding their range of applications. However, there is no comprehensive review in the literature that evaluates the efficacy and environmental impact of MNMs against PNMs in the environment. This critical review identifies major barriers preventing the widescale application of nano-enabled remediation and discusses strategies to increase the stability and activity of nanomaterials at reaction sites. The higher reactivity and versatility of MNMs, along with novel properties and functionalities, enable effective removal of a range of chemical pollutants from complex environmental matrices. Additionally, MNMs show significant improvement in mobility, reactivity, and controlled and targeted release of active ingredients for in situ remediation. However, the uncertainties associated with the adverse effects of some modification agents of MNMs are not well-understood, and require further in-depth investigations. Overall, our findings show that MNMs are potentially more efficient, cost-effective, and resilient for remediation of soil and sediment, water, and air pollution than PNMs. The possible action mechanisms of MNMs have been demonstrated for different environmental compartments. Conclusively, this work provides a path forward for developing effective nano-enabled remediation technologies with MNMs, which are widely applicable to a range of environmental contamination scenarios.

Reimagining safe lithium applications in the living environment and its impacts on human, animal, and plant system.

Lithium's (Li) ubiquitous distribution in the environment is a rising concern due to its rapid proliferation in the modern electronic industry. Li enigmatic entry into the terrestrial food chain raises many questions and uncertainties that may pose a grave threat to living biota. We examined the leverage existing published articles regarding advances in global Li resources, interplay with plants, and possible involvement with living organisms, especially humans and animals. Globally, Li concentration (<10-300 mg kg-1) is detected in agricultural soil, and their pollutant levels vary with space and time. High mobility of Li results in higher accumulation in plants, but the clear mechanisms and specific functions remain unknown. Our assessment reveals the causal relationship between Li level and biota health. For example, lower Li intake (<0.6 mM in serum) leads to mental disorders, while higher intake (>1.5 mM in serum) induces thyroid, stomach, kidney, and reproductive system dysfunctions in humans and animals. However, there is a serious knowledge gap regarding Li regulatory standards in environmental compartments, and mechanistic approaches to unveil its consequences are needed. Furthermore, aggressive efforts are required to define optimum levels of Li for the normal functioning of animals, plants, and humans. This review is designed to revitalize the current status of Li research and identify the key knowledge gaps to fight back against the mountainous challenges of Li during the recent digital revolution. Additionally, we propose pathways to overcome Li problems and develop a strategy for effective, safe, and acceptable applications.

Analytical challenges in detecting microplastics and nanoplastics in soil-plant systems.

Microplastics (MPx) and nanoplastics (NPx) are increasingly accumulating in terrestrial ecosystems, heightening concerns about their potential adverse effects on human health via the food chain. Techniques aimed at recovering the most challenging colloidal fractions of MPx and NPx, especially for analytical purposes, are limited. This systematic review emphasises the absence of a universal, efficient, and cost-effective analytical method as the primary hindrance to studying MPx and NPx in soil and plant samples. The study reveals that several methods, including density separation, organic matter removal, and filtration, are utilized to detect MPx or NPx in soil through vibrational spectroscopy and visual identification. Instruments such as Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, and fluorescence microscopy are employed to identify MPx and NPx in plant tissue. In extraction procedures, organic solvents and sonication are used to isolate NPx from plant tissues, while Pyrolysis GC-MS quantifies the plastics. SEM and TEM serve to observe and characterize NPx within plant tissues. Additionally, FTIR and fluorescence microscopy are utilized to identify polymers of MPx and NPx based on their spectral characteristics and fluorescence signals. The findings from this review clarify the identification and quantification methods for MPx and NPx in soil and plant systems and provide a comprehensive methodology for assessing MPx/NPx in the environment.

Estrogens in plants and emerging risks to human health.

Steroid estrogens (SEs) accumulate in agro-food systems through wastewater treatment and dairy manure, but very little is known about their potential impact on plants and dietary risk to human health. We conducted a meta-analysis to address key questions including, how plants respond to SEs under different environmental conditions, what is the accumulation potential of SEs in distinct plant families, and associated daily dietary intake risks to humans. Based on 517 endpoints, we revealed that various crop species show a heterogeneous response to SEs types (n = 140), SEs concentrations (n = 141), and exposure medium (n = 166). A subsidy-stress response was observed in terms of SEs accumulation for plant growth. The bioaccumulation of SE in plants was shown to be greatest in sand, followed by soil, and hydroponic media. Plants exposed to SEs exhibit considerable changes in physiological and biochemical characteristics. Surprisingly, food crops such as carrot and potato were found as major source of SEs daily intake in food chain but their consequences remains largely unknown. Further field-oriented research is needed to unveil the threshold levels for SEs in soil-plant systems as it may pose a global threat to human health. The state of knowledge presented here may guide towards urgently needed future investigations in this field for reducing the risk in SEs in agro-food systems.

Effects of micro-nano bubble with CO2 treated water on the growth of Amaranth green (Amaranthus viridis).

The micro and nano bubble (MNB) technology, due to its promising features and advantages, has become increasingly popular in agriculture. MNB-treated water positively impacts plant growth, especially when it is treated with a combination of gas-like carbon dioxide (CO2), injected through the MNB generator. Therefore, this study used MNB water with CO2 that are small bubbles of nanometer and micrometer diameters having several unique physical properties that make them useful for water treatments. This research evaluates the effect of MNBs and CO2-treated water on leafy vegetable Amaranth green (Amaranthus viridis). The experiment divided the Amaranth plants into three major groups, G1, G2, and G3, irrigated by MNB water with dissolved CO2, MNBs with only Air, and simple tap water, respectively. The first treatment group (G1) (MNBs with CO2) was further divided into three sub-divisions, i.e., G1A, G1B, G1C, and the second treatment group G2 (MNBs with Air) was divided into three sub-groups, i.e., G2A, G2B, and G2C, while the third group G3 with only one category as only controlled group. These sub-divisions of treatment groups G1 and G2 were done to investigate the impact of MNBs and CO2 treated water with different time durations. For example, in G1A, the water treatment with MNBs and CO2 was kept five minutes, for G1B 10 minutes, and G1C 15 minutes. Similar method was adopted for G2 as well. According to the results, water treated with MNB and CO2 has a significant (90%) impact on the Amaranth germination rate and plant growth. Specifically, pots irrigated with the MNBs + CO2-treated water showed better germination and plant growth rate than the MNBs + Air treated water. Overall, both treatment groups, G1 and G2, showed significantly higher impacts than the CK groups (simple water). Further, this experiment showed that the 10 and 15 minutes treatment of water (G1B, G1C and G2B, G2C) increased the stem height and root size compared to the 5 minutes treated water (G1A, G2A). This study concludes that the water with MNBs has a positive impact on the vegetables and can be an effective technology to improve crop yield.

Nanosized zinc oxide (n-ZnO) particles pretreatment to alfalfa seedlings alleviate heat-induced morpho-physiological and ultrastructural damages.

Global efforts are in rapid progress to tackle the emerging conundrum of climate change-induced heat stress in grassland ecosystems. Zinc oxide nanoparticles (n-ZnO) are known to play a crucial role in plants' abiotic stress regulation, but its response in alfalfa against heat stress has not been explored. This study aimed at assessing the effects of n-ZnO on alfalfa under heat stress by various morpho-physiological and cellular approaches. Five-week-old alfalfa seedlings were subjected to foliar application of n-ZnO as a pretreatment before the onset of heat stress (BHS) to evaluate its effect on heat tolerance, and as a post-treatment after heat stress (AHS) to evaluate recovery efficiency. In vitro studies on Zn release from n-ZnO by Inductively coupled plasma mass spectroscopy (ICPMS) disclosed that the particle uptake and Zn release were concentration dependent. The uptake and translocation of n-ZnO examined by transmission electron microscope (TEM) reveling showed that n-ZnO was primarily localized in the vacuoles and chloroplasts. TEM images showed that ultrastructural modifications to chloroplast, mitochondria, and cell wall were reversible by highest dose of n-ZnO applied before heat stress, and damages to these organelles were not recoverable when n-ZnO was applied after heat stress. The results further enlightened that 90 mg L-1 n-ZnO better prevented the heat stress-mediated membrane damage, lipid peroxidation and oxidative stress by stimulating antioxidant systems and enhancing osmolyte contents in both BHS and AHS. Although, application of 90 mg L-1 n-ZnO in BHS was more effective in averting heat-induced damages and maintaining better plant growth and morpho-physiological attributes compared to AHS. Conclusively, foliar application of n-ZnO can be encouraged as an effective strategy to protect alfalfa from heat stress damages while minimizing the risk of nanoparticle transmission to environmental compartments, which could happen with soil application.