Facile synthesis of nanomaterials as nanofertilizers: a novel way for sustainable crop production

Research Progress and Prospects of Nanozymes in Alleviating Abiotic Stress of Crops

The continuous destruction of the global ecological environment has led to increased natural disasters and adverse weather, severely affecting crop yields and quality, particularly due to abiotic stress. Nanase, a novel artificial enzyme, simulates various enzyme activities, is renewable, and shows significant potential in promoting crop growth and mitigating abiotic stress. This study reviews the classification of nanoenzymes into carbon-based, metal-based, metal oxide-based, and others based on synthesis materials. The catalytic mechanisms of these nanoenzymes are discussed, encompassing activities, such as oxidases, peroxidases, catalases, and superoxide dismutases. The catalytic mechanisms of nanoenzymes in alleviating salt, drought, high-temperature, low-temperature, heavy metal, and other abiotic stresses in crops are also highlighted. Furthermore, the challenges faced by nanoenzymes are discussed, especially in sustainable agricultural development. This review provides insights into applying nanoenzymes in sustainable agriculture and offers theoretical guidance for mitigating abiotic stress in crops.

Revealing critical mechanisms involved in carbon nanosol-mediated tobacco growth using small RNA and mRNA sequencing in silico approach

Nanomaterials have been shown to promote crop growth, yield and stress resistance. Carbon nanosol (CNS), a type of nanomaterial, is used to regulate tobacco shoot and root growth. However, information about the application of CNS to crop plants, especially tobacco, is still limited. Based on differential expression analysis and trend analysis, several miRNAs (miRN21-Novel-5p-mature, miR319b-Probable-5p-mature, miR160a-c-Known/Probable-5p-mature and miR156c-e-Known-5p-mature/star) and their target genes, including transcription factors (TFs), are likely responsible for the effect of CNS on promoting the growth of tobacco plants. In addition, we characterized nine TFs [Nitab4.5_00001789g0110 (NbbZIP), Nitab4.5_00001176g0010 (NbMYB), Nitab4.5_0001366g0010 (NbNAC), Nitab4.5_00000895g013 (NbMYB), Nitab4.5_0001225g0120 (NbNAC), Nitab4.5_0000202g0230 (NbDof), Nitab4.5_0002241g0010 (NbMYB-related), Nitab4.5_0000410g0060 (NbTCP), and Nitab4.5_0000159g0180 (NbC2H2)] associated with the response of tobacco to CNS according to the differential expression analysis, TF‒gene interaction network analysis and weighted correlation network analysis (WGCNA). Taken together, the findings of our study help understand CNS-mediated growth promotion in tobacco plants. The identification of candidate miRNAs and genes will provide potential support for the use of CNS in tobacco.

Water dispersible carbon nanomaterials reduced N, P, and K leaching potential in sandy soils: A column leaching study

Carbon nanomaterials (CNMs) - amendments with carbon in nanoscale form -could potentially enhance fertilizer delivery efficiency in agriculture, but their interaction with soil properties and nutrient co-mobility, especially in coarse-textured soils, remain poorly understood. We conducted a column leaching study in repacked soil columns to compare the co-leaching of novel water-dispersible CNMs and soil nutrients across two levels of CNMs applications (200 & 400 mg kg-1), two fertilization rates (low:80 mg kg-1 of N, P and K and high: 200 mg N kg-1, 100 mg P kg-1, 200 mg K kg-1, applied as ammonium nitrate, potassium phosphate, and potassium nitrate) and two soils (Spodosol with pH = 5.1, Alfisol with pH = 6.5). We imposed 12 leaching events to each column, with each leaching event adding water equivalent to the soil-pore volume (250 mL), resulting in cumulative leaching of 3000 mL of water through each column. CNMs applications reduced cumulative leaching losses of NO3-N (Spodosol: 8-12 %, Alfisol: 9-19 %), NH4-N (Spodosol: 2-14 %, Alfisol: 9-14 %), P (Spodosol: 23-27 %, Alfisol: 23-36 %) and K (Spodosol: 17-23 %, Alfisol: 24-26 %) compared to fertilized columns without CNMs. CNMs increased soil pH by up to 0.3 units (Spodosol) or 0.5 units (Alfisol), while lowering electrical conductivity by 15-20 % at the high fertilization rate in both soils. Columns with water-dispersible CNMs accumulated 25-30 % more total C in the base sections of the Alfisol compared to the Spodosol, indicating faster downward movement through the soil profile. Overall, we demonstrated that CNMs have the potential to reduce nutrient leaching in coarse-textured soils, which could be particularly beneficial in high-input intensive agricultural systems.

Recent advances in nano-fertilizers: synthesis, crop yield impact, and economic analysis

The escalating global demand for food production has predominantly relied on the extensive application of conventional fertilizers (CFs). However, the increased use of CFs has raised concerns regarding environmental risks, including soil and water contamination, especially within cereal-based cropping systems. In response, the agricultural sector has witnessed the emergence of healthier alternatives by utilizing nanotechnology and nano-fertilizers (NFs). These innovative NFs harness the remarkable properties of nanoparticles, ranging in size from 1 to 100 nm, such as nanoclays and zeolites, to enhance nutrient utilization efficiency. Unlike their conventional counterparts, NFs offer many advantages, including variable solubility, consistent and effective performance, controlled release mechanisms, enhanced targeted activity, reduced eco-toxicity, and straightforward and safe delivery and disposal methods. By facilitating rapid and complete plant absorption, NFs effectively conserve nutrients that would otherwise go to waste, mitigating potential environmental harm. Moreover, their superior formulations enable more efficient promotion of sustainable crop growth and production than conventional fertilizers. This review comprehensively examines the global utilization of NFs, emphasizing their immense potential in maintaining environmentally friendly crop output while ensuring agricultural sustainability.

Zinc-oxide nanoparticles ameliorated the phytotoxic hazards of cadmium toxicity in maize plants by regulating primary metabolites and antioxidants activity

Cadmium stress is a major threat to plant growth and survival worldwide. The current study aims to green synthesis, characterization, and application of zinc-oxide nanoparticles to alleviate cadmium stress in maize (Zea mays L.) plants. In this experiment, two cadmium levels (0, 0.6 mM) were applied to check the impact on plant growth attributes, chlorophyll contents, and concentration of various primary metabolites and antioxidants under exogenous treatment of zinc-oxide nanoparticles (25 and 50 mg L-1) in maize seedlings. Tissue sampling was made 21 days after the zinc-oxide nanoparticles application. Our results showed that applying cadmium significantly reduced total chlorophyll and carotenoid contents by 52.87% and 23.31% compared to non-stress. In comparison, it was increased by 53.23%, 68.49% and 9.73%, 37.53% with zinc-oxide nanoparticles 25, 50 mg L-1 application compared with cadmium stress conditions, respectively. At the same time, proline, superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase contents were enhanced in plants treated with cadmium compared to non-treated plants with no foliar application, while it was increased by 12.99 and 23.09%, 23.52 and 35.12%, 27.53 and 36.43%, 14.19 and 24.46%, 14.64 and 37.68% by applying 25 and 50 mg L-1 of zinc-oxide nanoparticles dosages, respectively. In addition, cadmium toxicity also enhanced stress indicators such as malondialdehyde, hydrogen peroxide, and non-enzymatic antioxidants in plant leaves. Overall, the exogenous application of zinc-oxide nanoparticles (25 and 50 mg L-1) significantly alleviated cadmium toxicity in maize. It provides the first evidence that zinc-oxide nanoparticles 25 ~ 50 mg L-1 can be a candidate agricultural strategy for mitigating cadmium stress in cadmium-polluted soils for safe agriculture practice.

Exogenous taurine administration abates reproductive dysfunction in male rats exposed to silver nanoparticles

The broad contemporary applications of silver nanoparticles (AgNPs) have been associated with various toxicities including reproductive toxicity. Taurine is well acknowledged for its potent pharmacological role in numerous disease models and chemically-mediated toxicity. We investigated the effect of taurine on AgNPs-induced reproductive toxicity in male rats. The animals were intraperitoneally injected with AgNPs (200 μg/kg) alone or co-administered with taurine at 50 and 100 mg/kg for 21 successive days. Exogenous taurine administration significantly abated AgNPs-induced oxidative injury by decreasing the levels of oxidative stress indices while boosting antioxidant enzymes activities and glutathione level in the hypothalamus, testes and epididymis of exposed animals. Taurine administration alleviated AgNPs-induced inflammatory response and caspase-3 activity, an apoptotic biomarker. Moreover, taurine significantly improved spermiogram, reproductive hormones and the marker enzymes of testicular function in AgNPs-treated animals. The ameliorative effect of taurine on pathological lesions induced by AgNPs in the exposed animals was substantiated by histopathological data. This study provides the first mechanistic evidence that taurine supplementation affords therapeutic effect against reproductive dysfunction associated with AgNPs exposure in male rats.

Elevated CO2 differentially attenuates beryllium-induced oxidative stress in oat and alfalfa

Elevated CO2 (eCO2 ) is one of the climate changes that may benefit plant growth under emerging soil contaminants such as heavy metals. In this regard, the morpho-physiological mechanisms underlying the mitigating impact of eCO2 on beryllium (Be) phytotoxicity are poorly known. Hence, we investigated eCO2 and Be interactive effects on the growth and metabolism of two species from different groups: cereal (oat) and legume (alfalfa). Be stress significantly reduced the growth and photosynthetic attributes in both species, but alfalfa was more susceptible to Be toxicity. Be stress induced reactive oxygen species (ROS) accumulation by increasing photorespiration, subsequently resulting in increased lipid and protein oxidation. However, the growth inhibition and oxidative stress induced by Be stress were mitigated by eCO2 . This could be explained, at least partially, by the increase in organic acids (e.g., citric acid) released into the soil, which subsequently reduced Be uptake. Additionally, eCO2 reduced cellular oxidative damage by reducing photorespiration, which was more significant in alfalfa plants. Furthermore, eCO2 improved the redox status and detoxification processes, including phytochelatins, total glutathione and metallothioneins levels, and glutathione-S-transferase activity in both species, but to a greater extend in alfalfa. In this context, eCO2 also stimulated anthocyanin biosynthesis by accumulating its precursors (phenylalanine, coumaric acid, cinnamic acid, and naringenin) and key biosynthetic enzymes (phenylalanine ammonia-lyase, cinnamate hydroxylase, and coumarate:CoA ligase) mainly in alfalfa plants. Overall, this study explored the mechanistic approach by which eCO2 alleviates the harmful effects of Be. Alfalfa was more sensitive to Be stress than oats; however, the alleviating impact of eCO2 on Be stress was more pronounced in alfalfa.

Carbon nanomaterials are a superior soil amendment for sandy soils than biochar based on impacts on lettuce growth, physiology and soil biochemical quality

A significant bottleneck of current agricultural systems remains the very low agronomic efficiency of conventional agrochemicals, particularly in sandy soils. Carbon nanomaterials (CNMs) have been proposed to address this inefficiency in sandy soils, which could potentially improve soil fertility and enhance crop growth and physiological processes. However, the effects of different rates of CNMs on crop physiological and soil biochemical quality in sandy soils must be compared to other carbon sources (e.g., biochar) before CNMs can be broadly used. To address this, a 70-day pot experiment was set up, growing lettuce under ten treatments: a negative control with no CNMs, biochar or fertilizer; a fertilizer-only control; three CNMs-only unfertilized treatments (CNMs at 200, 400 and 800 mg kg-1 soil); two biochar treatments with fertilizer (biochar at 0.5% and 1% by soil mass + fertilizer); and three CNMs treatments with fertilizer (CNMs at 200, 400 and 800 mg kg-1 soil + fertilizer). A novel amorphous, water-dispersible, and carboxyl-functionalized CNMs with pH of 5.5, zeta potential of -40.6 mV and primary particle diameter of 30-60 nm was used for this experiment. Compared to the fertilizer-only control, CNMs applied at low to medium levels (200-400 mg kg-1) significantly increased lettuce shoot biomass (20-21%), total chlorophyll (23-27%), and fluorescence and photosynthetic activities (4-10%), which was associated with greater soil nutrient availability (N: 24-58%, K: 68-111%) and higher leaf tissue accumulation (N: 25-27%; K: 66%). Low to medium levels of CNMs also significantly increased soil biochemical properties, such as higher soil microbial biomass carbon (27-29%) and urease enzyme activity (34-44%) relative to fertilizer-only applications. In contrast, biochar (0.5%) increased lettuce biomass relative to fertilizer-only but had no significant effect on soil fertility and biological properties. These results suggest that CNMs at low to medium application rates are a superior carbon-based amendment relative to biochar in sandy soils.

Nanofertilizers: The Next Generation of Agrochemicals for Long-Term Impact on Sustainability in Farming Systems

The microflora of the soil is adversely affected by chemical fertilizers. Excessive use of chemical fertilizers has increased crop yield dramatically at the cost of soil vigor. The pH of the soil is temporarily changed by chemical fertilizers, which kill the beneficial soil microflora and can cause absorption stress on crop plants. This leads to higher dosages during the application, causing groundwater leaching and environmental toxicity. Nanofertilizers (NFs) reduce the quantity of fertilizer needed in agriculture, enhance nutrient uptake efficiency, and decrease fertilizer loss due to runoff and leaching. Moreover, NFs can be used for soil or foliar applications and have shown promising results in a variety of plant species. The main constituents of nanomaterials are micro- and macronutrient precursors and their properties at the nanoscale. Innovative approaches to their application as a growth promoter for crops, their modes of application, and the mechanism of absorption in plant tissues are reviewed in this article. In addition, the review analyzes potential shortcomings and future considerations for the commercial agricultural application of NFs.

Starch-based controlled release fertilizers: A review

Starch, as a widely available renewable resource, has the potential to be used in the production of controlled-release fertilizers (CRFs) that support sustainable agriculture. These CRFs can be formed by incorporating nutrients through coating or absorption, or by chemically modifying the starch to enhance its ability to carry and interact with nutrients. This review examines the various methods of creating starch-based CRFs, including coating, chemical modification, and grafting with other polymers. In addition, the mechanisms of controlled release in starch-based CRFs are discussed. Overall, the potential benefits of using starch-based CRFs in terms of resource efficiency and environmental protection are highlighted.

Effects of Phytogenically Synthesized Bimetallic Ag/ZnO Nanomaterials and Nitrogen-Based Fertilizers on Biochemical and Yield Attributes of Two Wheat Varieties

Wheat is the most important staple food worldwide, but wheat cultivation faces challenges from high food demand. Fertilizers are already in use to cope with the demand; however, more unconventional techniques may be required to enhance the efficiency of wheat cultivation. Nanotechnology offers one potential technique for improving plant growth and production by providing stimulating agents to the crop. In this study, plant-derived Ag/ZnO nanomaterials were characterized using UV-Vis spectroscopy, SEM, EDX, FTIR, and XRD methods. Various concentrations of phytogenically synthesized Ag/ZnO nanomaterials (20, 40, 60, and 80 ppm) and nitrogen-based fertilizers (urea and ammonium sulphate 50 and 100 mg/L) were applied to wheat varieties (Galaxy-13 and Pak-13). The results obtained from this research showed that application of 60 ppm Ag/ZnO nanomaterials with nitrogenous fertilizers (50 and 100 mg/L) were more effective in improving biochemistry and increasing yield of wheat plants by reducing enzymatic and non-enzymatic antioxidants (proline content, soluble sugar content, malondialdehyde, total phenolic content, total flavonoid content, superoxide dismutase, peroxidase, and catalase); and significantly increasing the protein content, number of grains per pot, spike length, 100-grain weight, grain yield per pot, and harvest index of both wheat varieties, compared to untreated plants. These findings allow us to propose Ag/ZnO nanomaterial formulation as a promising growth- and productivity-improvement strategy for wheat cultivation.