Since the beginning of human civilisation, agriculture has played a crucial role in the economy worldwide. In fact, in 2018, its contribution was 4% to global GDP and more than 25% to the GDP of some developing countries. It is a backbone of developing countries as it ensures food security, and growth in agriculture can raise the income of the poorest, leading to a reduction in poverty faster than any other sector. However, the efforts to increase the productivity of agriculture are facing various challenges of biotic and abiotic stress.
The majority of scientists are working to solve this problem by using various modern technologies and techniques such as CRISPR/Cas9 for Genetic manipulation, Intensive tillage, Monoculture, Use of synthetic fertilizers, irrigation technologies, chemical pest control Etc. However, here we will discuss the application of Nanotechnology: one of the emerging techniques contributing to the agrotechnological revolution.
Nanomaterials classification:
Before proceeding with the applications, first, let us understand what Nanotechnology is? Its classification and which Nanoparticles are used for enhancement of agriculture? Nanotechnology is the science, engineering and technology used to produce, synthesise, nanoscale materials known as Nanoparticles/Nanomaterials, with at least one dimension (height, length, width) ranging between 1 to 100 nm. Scientist Norio Taniguchi first coined the term in 1974.
The nanoparticles/Nanomaterials are classified based on the following characteristics:
Dimensions:
0D: nanoscale dimensions, (quantum dots)
1D: nanofibers and nanowires (one of dimension in macro-scale),
2D: nanosheets and thin films, and
3D: materials in bulk.
Chemical nature:
Carbon: fullerenes, graphene, and carbon nanotubes (CNTs)
Ceramic (metal oxides): TiO2, ZnO, and FeO2
Metal: Au, Ag, Cu, and Ni
Polymeric compounds: cellulose, gelatine, pullulan, chitosan, alginate, and gliadin
Depending upon the applications and sectors like health care, Pharmaceuticals, Cosmetic industry, Biotechnology, Agriculture, Etc. the specific nanomaterials are selected. Here in this article, we will focus on applications of various nanoparticles, for instance, polymeric nanoparticles, Silver nanoparticles, Nano alumino-silicates, Titanium dioxide nanoparticles, Etc., which play a pivotal role in combatting unprecedented challenges faced by agriculture. Significantly, they are used to reduce the utilization of chemical sprays, minimize nutrient losses, and increase agricultural produce’s yield through pest and nutrient management.
Applications:
Fertilizers
Determining factors for the development of new fertilizer application strategies using nanofertilizers in pastures (Mejias et. al. 2021)
The use of chemical fertilizers does supplement essential nutrient requirements and increase the yield, but in the long run, they degrade the soil quality, pollute air and water, release greenhouse gasses, and bring hazards to the environment. Specifically, the environmental problem arises as nutrients lower than minimum desired concentration from conventional fertilizers reach the target site due to leaching loss of chemicals, drift, runoff, hydrolysis photolytic and microbial degradation, thus the need for repeated use of fertilizers. In contrast, Nano fertilizers can regulate the release of nutrients with the uptake demand of plants, direct internalization by crops, and escape the interaction with soil, water, air and microbes, consequently preventing undesirable loss of nutrients and protection of soil degradation and environmental loss. For example, the use of porous nanomaterials, such as zeolites, clay or chitosan, enhance demand-based uptake; Ammonium charged zeolites improve phosphorus availability for plant uptake. Similarly, application of nano calcite (CaCO3-40%) application with nano SiO2 (4%), MgO (1%), and Fe2O3 (1%) improved the uptake of Ca, Mg, and Fe, and also intake of P with micronutrients Zn and Mn. A low dose of Zinc oxide is required to boost the growth and physiological responses (shoot and root elongation), and photosynthesis in many plant species. In the case of zinc-deficient soil, the application of zinc oxide nanoparticles in combination with other fertilizers showed a 91% increased productivity, while bulk zinc-oxide could offer 31% of increased productivity.
Climate change
The increase in greenhouse gases, acid rain, rapid melting of Glacier and depletion of the ozone layer is the clear sign for change climate which is a significant threat to food security and researchers working to develop technologies and practices towards sustainable agriculture. Studies showed that the application of nano fertilizers shorten the life cycle of wheat by 23.5% (130 days compared to 170 days) for yield production from the sowing date in contrast to the plant supplied with conventional fertilizers, indicating its advantage and potential in drought and sudden flash flood-prone area where early maturity is essential for the crop sustainability. Furthermore, nanomaterials play a crucial role in the remediation of heavy metals pollution; certainly, nano-Si at 2.5 mM improves stress caused by Cd accumulation and even Pb, Cu, and Zn in rice plants which is another advantage over traditional fertilizers.
Nano sensors
The development of Nano sensors helps farmers head towards efficient modern farming as it serves the job of monitoring nutrient requirements of soil, crop growth, specific plant affected by the disease, ensuring overall soil and plant health. Moreover, compared to conventional sensors, these nano sensors hold numerous advantages like a high surface-to-volume ratio, instant response within seconds, nanogram or lesser amounts of detection with reliable results, are practicable in different matrixes, and support fast electron transfer kinetics. For instance, detection of pests such as Polymyxa betae (Responsible for Rhizomania disease in sugar beet) is much more efficient and rapid with a quantum dot-FRET-based nano biosensor. Furthermore, Trichoderma harzianum (fungal pathogen) was detected using ZnO nanoparticles/chitosan nanocomposite modified gold electrode, and Au Nanoparticles tagged with horseradish labelled antibodies for detection of the Pantoea stewartii (plant bacterial pathogen).
Nano pesticides
Administration of nano-fertilizers/Nano Pesticides
According to the Food and Agriculture Organization of the United Nations (FAO), the average food loss pre-and post-harvest is 20-40%; meanwhile, the extensive use of chemical pesticides leads to resistance in pathogens and insects; bioaccumulation in agriculture, livestock, and in organisms of the water environment. Nevertheless, Nano pesticides formulations can control the delivery (root zones or inside the plant) and have a higher effect with lower chemical dose; thereby, revolutionize the control of pests and insects and promoting the widening of plant-based systemic acquired resistance (SAR) against pests. The use of silica nanosphere increases the capability of pesticides to penetrate and reach plant cell sap, thus controlling chewing or sucking insects like aphids. The reduction in the catalytic action of trypsin (an essential insect protease) is achieved by latex fabricated bioactive AuNPs, which could be because of metallic NPs with proteins via covalent interactions; hence, bio-controlling destructive insects. There are different types of nano formulations: Microemulsion (droplet: <50nm), nano emulsion (droplet size 20-200nm), nano dispersion (nanocrystal dispersed in liquid medium), and nanoencapsulation committed to ensuring safe application and reduction in abusive use of conventional pesticides.
Conclusion
Without a doubt, the cutting-edge research in nano formulation based fertilizers or pesticides increasing dispersion and wettability of nutrients, Nano sensors & remote-sensing based monitoring is increasing precision in farming, reducing cost and efforts and significantly increasing efficiency & productivity with environmentally sound development.
References:
Ghidan, A. Y., Kahlel, A. M. S., & Al-Antary, T. M. (2020). Effect of nanotechnology liquid fertilizers on yield and nitrogenous compounds of broad bean (Vicia faba l.). Fresenius Environmental Bulletin, 29(6), 41244128.
Mejías, J. H., Salazar, F. J., Pérez, L., Hube, S., Rodriguez, M., & Alfaro, M. A. (2021). Nanofertilizers: a cutting-edge approach to increase nitrogen use efficiency in grasslands. Frontiers in Environmental Science, 9, 52.
Paramo, L. A., Feregrino-Pérez, A. A., Guevara, R., Mendoza, S., & Esquivel, K. (2020). Nanoparticles in agroindustry: Applications, toxicity, challenges, and trends. Nanomaterials, 10(9), 1654.
Priyanka, P., Kumar, D., Yadav, K., & Yadav, A. (2019). Nanopesticides: Synthesis, Formulation and Application in Agriculture. In Nanobiotechnology Applications in Plant Protection (pp. 129-143). Springer, Cham.
Shang, Y., Hasan, M., Ahammed, G. J., Li, M., Yin, H., & Zhou, J. (2019). Applications of nanotechnology in plant growth and crop protection: a review. Molecules, 24(14), 2558.