The rise of green nanotechnology in agriculture
Green nanotechnology has significant potential for use in agriculture, particularly due to its antifungal properties and ability to control fungal diseases. Biotic stresses in agriculture have caused widespread damage worldwide, and green nanoparticles (NPs) provide eco-friendly alternatives to traditional chemical treatments, which are frequently toxic and harmful to the ecosystem.
Green NPs could become an important tool in modern agricultural practices and environmental remediation if appropriate research is conducted to identify cost-effective production methods as well as safe and sustainable applications. To understand the potential of green NPs for sustainable agriculture and identify potential risks, ongoing research is exploring the effectiveness of various green metallic NPs, carbon and graphene nanotubes, nanocomposites, and other nanomaterials against pathogens on crops.
These green NPs are found to be more effective against pathogens on crops and humans than conventional fungicide approaches. They are very effective against fungi that affect cereal crops, including Fusarium oxysporum, Botrytis cinerea, and Candida species, among others. The green NPs developed using green synthesis methods are both cost-effective and environmentally friendly.
However, research is still required to identify the best methods for applying green NPs for crop production and sustainable agriculture. Furthermore, studies should be undertaken to establish the most cost-effective methods of making and deploying green nanoparticles at a large field size where there is fungal attack that diminishes agricultural output and affects global crop production.
The rise of fungal diseases in agriculture
Fungal infections have been responsible for agricultural losses exceeding 200 billion euros annually. Chemical fungicide sprays are not an environmentally acceptable way to treat fungal illnesses since they pollute the environment and pose a risk to human health as well as other biotic life forms. However, these chemical fungicides appear overused due to their affordability and ease of application.
Fungi account for 70–80% of the losses brought on by microbial diseases in agriculture. It is believed that there are around 1.5 million species of the fungal kingdom, and most of these fungal pathogens cause plant illnesses and production losses. Animal pests account for around 18% of agricultural crop losses, with microbiological diseases and weeds accounting for 16% and 34% of losses, respectively.
Green nanoparticles as an antifungal solution
To address the present challenges of global warming, overconsumption of natural resources, and an ever-rising population, there is a need to shift from unsustainable traditional agricultural practices, causing the growth of chemical fungicides, to eco-friendlier practices for ensuring global food security. The promotion of green nanotechnology is a suitable option for sustainable management of various plant pathogens without affecting the environment.
Green nanoparticles (NPs) demonstrate the potential of antimicrobial activities for effective fungal pathogen control compared to conventional fungicides. In addition to ensuring plant health, nanoparticles satisfy agriculture’s growing need for high output. The limits of chemicals and the potential of green nanoparticles, which provide fresh approaches to managing fungicides that cause fungal illnesses in agriculture, are the primary topics of this review.
Mechanisms of antifungal activity
Green nanoparticles’ antifungal effects are attributed to their electropositive surfaces, which oxidize plasma membranes and allow entry into the pathogen body. The role of reactive oxygen species (ROS) in the antibacterial activity of CeO2 NPs is also highlighted, as exposure to these particles can increase intracellular ROS levels in fungal cells.
ROS generated by green NPs can disrupt cell walls, leading to the death of fungal cells. ROS can also activate the immune system, aiding in the fight against fungal infections. Additionally, ROS can damage the fungal membrane, preventing the transport of essential molecules, and react with fungal enzymes, impairing their ability to catalyze important reactions. ROS can also damage the DNA of fungal cells, leading to mutations that prevent the cells from reproducing and spreading.
Antifungal applications of green nanoparticles
Various green NPs have demonstrated effective antifungal activity against a range of plant pathogens:
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Zinc Oxide (ZnO) NPs: ZnO NPs based on Parthenium hysterophorus plant extracts significantly slowed down the growth of A. flavus and Aspergillus niger. ZnO NPs created using Syzygium aromaticum bud extracts showed efficacy against Fusarium graminearum, inhibiting mycelial cell growth and the synthesis of mycotoxins.
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Graphene Oxide (GO) and Iron Oxide (Fe3O4) Nanocomposite: The GO-Fe3O4 nanocomposite effectively reduced spore germination of Plasmopara viticida, the pathogen that causes downy mildew in crops.
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Silver (Ag) NPs: Ag NPs disrupt fungal cell membranes and halt cellular processes, providing strong antifungal properties against a broad spectrum of fungi, including Rhizoctonia solani, Macrophomina phaseolina, Alternaria alternata, Curvularia lunata, Botrytis Cinerea, and Sclerotinia Sclerotiorum.
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Copper (Cu) NPs: Cu NPs synthesized using Aloe Vera, Citrus Medica, and Syzygium aromaticum extracts have shown outstanding antifungal action against pathogens like F. graminearum, Fusarium culmorum, F. oxysporum, Aspergillus niger, Aspergillus flavus, and Penicillium spp.
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Gold (Au) NPs: Au NPs synthesized using a variety of plant extracts, such as Memecylon edule, Punica granatum, Capsicum annuum, Magnolia kobus, and Artemisia dracunculus, have also demonstrated effective antifungal properties when combined with appropriate reducing agents.
The overuse of pesticides and other chemicals, along with conventional methods for nanoparticle synthesis, has detrimental impacts on soil fertility, soil microorganisms, and the health of people, plants, and animals. By altering metabolic and physiological processes, the increasing use of conventional fertilizers has led to the emergence of pathogen strains that are resistant to them and delays the growth of photosynthetic pigments and plant reproductive organs.
Sustainable applications of green nanoparticles in agriculture
Green nanoparticles offer a multifaceted approach to fighting fungal infections in crops, leveraging both direct antifungal properties and indirect benefits through soil and plant health improvement. When cells are exposed to green NPs, they produce more ROS and OH radicals, reducing regulation of antioxidant machinery and oxidative enzymes, disrupting cellular integrity and osmotic balance, and decreasing pathogenicity.
The applications of green nanoparticles in sustainable agriculture include:
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Nano-coatings on seeds: Nano-coatings can speed up germination rates, protect against pests and diseases, and provide controlled release of nutrients during early growth stages of plants.
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Nano-based water filtration and adsorbent systems: Nanobased filtration alleviates the effects of heavy metals and other contaminants in wastewater, ensuring pathogen and toxic-free clean water for irrigation.
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Nano-based pesticides and fertilizers: The development of nano-scale formulations can improve the efficacy of pesticides and fertilizers, enhancing targeted delivery and reducing environmental contamination.
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Nano-carriers for agricultural inputs: The use of nano-carriers can improve the efficiency of delivering various agricultural inputs, primarily pesticides and nutrients, to the plants.
By employing Cm-AgNPs, nanoscale products can be developed to combat post-harvest pathogenic fungi in crops, which will ultimately benefit society and contribute towards achieving the SDGs ‘#Zero Hunger’ goal.
Challenges and future prospects
While green nanotechnology is a promising approach, there are still some concerns that need to be addressed before large-scale application in the agriculture sector. The antifungal management often requires nano-hybrid materials, which are expensive to produce due to the high-tech devices and energy inputs needed.
Additionally, the concentration of nanocomposites used in the field can determine their potential harm. Compared to the concentrations of chemical-based insecticides and fungicides, the working concentrations of nanocomposites are relatively low. The capacity of biodegradable polymers to easily translocate inside plant tissues and have antifungal properties is an area that requires further research.
The time, money, and resources required to produce green NTs for agriculture can be recovered by establishing biological synthesis techniques. Additionally, it may successfully reduce the quantities of environmentally hazardous chemicals needed for the commercial synthesis of non-composite materials and nanomaterials.
Despite these challenges, the global green nanotechnology market is expected to grow significantly in the coming years, with high contributions from various countries. The consumption and production of green NPs synthesized by eco-friendly methods are growing rapidly, as industries seek sustainable alternatives for their businesses. By embracing green nanotechnology, the agriculture sector can enhance crop production, improve resource efficiency, and offer innovative, eco-friendly approaches to control fungal diseases, contributing to global food security and sustainable development.
