Conventional agriculture often relies on bulky doses of fertilizers and pesticides that have adversely affected living beings as well as ecosystems. As a basic tenet of sustainable agriculture, minimum agrochemicals should be used so that the environment can be protected and various species can be conserved.
Further, sustainable agriculture should be a low input system, where the production costs are lower and net returns are higher. The application of nanotechnology in agriculture can significantly enhance the efficiency of agricultural inputs and thus it offers a significant way to maintain sustainable development of agroecosystems via nanoparticles.
What Are Nanoparticles?
Nanoparticles are basically tiny metal-based matter particles, that have the capability to become an integrated system of various active principles consisting of particles, so to perform functioning inside an experimental organism in result to make our desired organism more beneficial on grounds of functioning in every aspect.
Importance and Future of Nanotechnology
Nanotechnology is an advanced emerging field of science that deals with the alterations of matter at a specific size scale of 1- 100 nm. The International standardization organization (ISO)’s Technical committee 229 defined nanotechnology in 2010 as “Knowing and handling objects and organisms at the nanoscale of 1-100 nm”.
Thus, future-oriented technology analysis (FTA) has been engaged for the last five decades for formulations of various rules, rights, and governance structures in the emerging field of nanotechnology. In comparison to other countries, US and Germany were the pioneers in the establishment and development of nanotechnology. 10 years back US National Science and Technology council started working on nanotechnology’s research and development.
Factors of Nanotechnology Development
The development of nanotechnology relied on many factors. The prime factors were technology forecasting, technology-related research, and investigations at the ground basic level. Huge contributions of scientists, lawmakers, media, and followers in form of users of nanotechnology50 oriented products lead to the development of this technology.
Generations of Nanotechnology Development
The development of nanotechnology can be explained in four generations – the first generation –a stage of slow working passive nanoparticles (NP)s, second-generation –stage of active advanced nanoparticles, third generation-the technically oriented nanotechnology, and the fourth generation- stage of integration of various fields (biotechnology, bioinformatics, pathology, etc.) for development of nanotechnology.
In 1980’s, two visions acted as a pioneer for the establishment of nanotechnology in UK. The first vision was of ERIC DREXLER who describes briefly the prospectus of nanotechnology in his book “Engines of Creation”: The coming era of nanotechnology. Drexler created molecular machines which lead to manipulations of matter at nanoscale. Thus, in late 1980-1990 Drexler’s efforts lead to a new revolution of nanotechnology.
The second vision was of US National initiatives was taken in 2000, after which the US science policy became very clear about the proper functioning of nanotechnology. The biggest step for the enhancement of nanotechnology was taken by the National Science and technology council (NSTC) in 1998. The basic agenda for making National Nanotechnology Initiative (NNI) was to research social issues related to nanotechnology-oriented products because people had doubts regarding nanotechnology and its products.
In the year 2010, a report named as “nanotechnology research directions for social needs in 2020” was published. After this report, again workshops were organized on social nanotechnology issues but a big change was a large number of stakeholders and experts belonging from various social sectors such as physical-biological sciences, medicines, economics, philosophy etc were attended the workshop.
In the year 2011, Mihail C. Roco, senior advisor for nanotechnology at the National science foundation (NSF) explained two phases of nanotechnology such as “NANO -1” (2001-2010): this focused on the interdisciplinary action at the nanoscale.
“NANO-2” (2011-2020): focused on the various benefits of nanotechnology (NNT). In Germany the Federal German ministry for education and research (BMBF) played a major role in development of nanotechnology. The main work of (BMBF) started in late 1980’s. Its main work is to monitor development of nanotechnology as well as its effects on society. In 1990’s (BMBF) starting investigating various branches of nanotechnology which involved in matter’s like increasing funds for nanotechnology development.
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Nano Komission
Finally, the efforts of (BMBF) resulted into formation of first six National nanotechnology centres. The main functions of these centres were to make strong connections between science and industries. In the year 2006 the Federal Ministry for environment, nature conservation and nuclear safety (BMW) formed a body called “NANO KOMMISSION” which was a stakeholder commission of nanotechnology applications and products. NANOKOMISSION was made up of various members from different fields such as consumer organization, women organization, medical organization, academic government bodies etc.
NANOKOMMISSION’s aim was to investigate the effects of nanotechnology upon society. In the year 2007 “Nano Initiative Action plan 2010” became main part of high-tech strategy of German government. Only because of this action plan ministries such as BMAS, BMU, BMELV, BMVG, BMG BMWI became part of German nanotechnology initiative. After this “Action plan nanotechnology 2015” was launched whose aim was to regulate nanotechnology.
In the year 2011 NANOKOMMISSION published its final report in which it was written that the German Federal government should make a national cross-departmental internet platform for increased knowledge regarding the scope, applications of nanotechnology. Thus, it can be concluded that in the last 27 years FTA has functioned as the main source for the development of nanotechnology in the 21st century. In the current scenario, nanotechnology is playing a major role in different fields such as food science, agronomy, food management, etc.
Use of Nanoparticles In Daily Base Products
The use of nanoparticles is increasing in daily base products but the mechanistic insight of nanoparticles, their penetration inside the desired system is lacking. On the other side, nanoparticles have toxic effects on the living systems and the environment. These nanoparticles reach at top of the food chain by the process of biomagnification, when plants are treated with nanoparticles for enhancing the crop yield.
It can be said that nanoparticles have grey shade in their information and utilization and have both merits and demerits. Roco et al. have speculated that Nanoparticles show toxicity when they are used for studying seed germination processes.
Though, future researches and clarification need to be done for studying the absorption and action of nanoparticles on plants. The nano-mediated agri-application for sustainable crop production (phytonanotechnology) is a potential mode to alter the conventional, less effective, bulky, and toxic system of plant production and protection. This is because, nano-derived fertilizers, pesticides, and herbicides are target-specific and have controlled release systems for delivering the biomolecules on essential sites.
Common Agriculturally Important Nanoparticles
Silver Nanoparticles
These nanoparticles (size range 10-20nm) consist of silver ions as their important constituent. These particles have high activity and effectiveness inside living systems. These can be made via various methods such as physical, chemical and biological method etc. Silver nanoparticles have been used to fight against various harmful microbes.
As an example, spot blotch disease has been cured by silver nano particles. Other uses of Sliver nanoparticles include breaking of seed dormancy, increasing seed vigour index, and also increase in seedling fresh weight. Silver nanoparticles are easy to synthesize and are environment friendly. Investigations regarding stress tolerance in plants due to silver nanoparticles is still underway.
Zinc Oxide Nanoparticles
Soils as well as plants generally face the deficiency of zinc which is due to the lower availability of zinc and its limited amount in calcium carbonate enriched soils due to alkaline pH. To mitigate this, zinc sulphate fertilizer is used as alternatives, but, even then plants suffer from zinc deficiency. Zinc oxide nanoparticles are the best option to alleviate the zinc deficiency as they are easily absorbed in plants due to their small size and large surface area. Since the zinc oxide nanoparticles are of the size 100 nm, they are very efficient.
For synthesizing these NPs, zinc sulfate heptahydrate is dissolved in water. Simultaneously, the desired living organism such as plants and animals are used for extraction of bio active extract. The extract is made in water or ethanol. Then at appropriate pH, both the synthesized solutions are mixed and the desired zinc oxide nanoparticles are obtained. These nanoparticles can be a cheap, sustainable and environment friendly solution to various problems of plants such as zinc deficiency, pathogenic attacks etc.
Titanium Dioxide Nanoparticles
Titanium dioxide NPs (TiO2 NPs) are 5–30 nm in size and highly manufactured and used in the world. These nanoparticles are very much in demand due to the photocatalyst property of titanium. Because of this property, these are used in pigment formations. These nanoparticles enhance growth and photosynthesis of plants. Latef et al. have revealed that titanium dioxide nanoparticles (nTiO2) ameliorated the soil salinity in broad bean, a widely growing leguminous crop.
Moreover, it is applied via roots or foliar spray in very low concentrations to stimulate the plant growth enzyme activity, photosynthesis of chlorophyll content facilitates the nutrient uptake, stress tolerance promotion, and yield as well as quality of crop. Moreover, pests are also killed due to nTiO2 residues inside plant body and hence it acts as an efficient pesticide.
Iron Oxide Nanoparticles
Iron oxide nanoparticle (Fe2O3NPs) is very crucial oxide nanomaterial that is applied in agriculture widely because it can replace the traditional shortcoming Fe fertilizers. Moreover, it is very essential in catalysis, biomedicine, water treatment and in other fields. Iron-NPs are commonly <10–20 nm in size and exhibit the inimitable form of magnetism and are synthesized by mechanochemical, chemical or by biological methods. They can be in various shapes such as rods, spheres, cubes, self-oriented flowers etc.
Naturally, Fe is mainly abundant in the form of Fe3+ but the plants and other living being can uptake only in Fe2 form. Moreover, various physiological response in plants such as leghemoglobin formation in nodules, chlorophyll synthesis, redox reaction, respiration etc. are mediated with the help of Fe. But, only in required proportion because deficiency or excess, both are harmful.
The deficiency of Fe is prevelant among different crops. Sánchez-Alcalá et al. have reported that Arachis hypogaea (Peanut) is highly sensitive to Fe deficiency. Studies revealed that iron oxide nanoparticles positively affected the plant growth and production as has been exemplified in peanut, soybean and wheat crops.
Cu-Based NPs
High abundance and low cost of copper (Cu) make it attractive for the sustainable preparation of Cu-based nanomaterials (Cu-NPs). Transitions properties of Cu open the multiple potential ways such as optics, sensor, solar cells, water treatment etc. Cu-NPs are in size range of 42-146 nm and in cube, hemisphere and agglomerate shape.
The synthesis of Cu-NPs is also based on bottom-up” (atomic-level precursors utilized for nanosized materials) or “top-down” (breaking down of bulky solid into smaller or nano components) approach. In many cases, the Cu-NPs susceptibility for undergo oxidation allows them to form stable Cu-oxide.
Interestingly, Giannousi et al have synthesized smaller sized (11–21 nm) of Cu-based NPs (Cu/Cu2O, Cu2O, CuO NPs). Cu-based NPs are reported as the potential agro-fungicides and were revealed to be affective against a range of phytopathogens (Fusarium sp., Phoma destructiva, C. lunata, A. alternate, F. oxysporum, Penicillium italicum, P. digitatum and, R. solani).
Giannousi et al. have reported the Cu2O NPs as agro-fungicides for suppression of Phytophthora infestans, a major disease-causing agent of plant. Interestingly, Cu-NPs induce the oxidative stress and it can act in a different way for different fungus species.
Conclusion and Future Perspectives
To conclude the era of nanotechnology is vastly emerging and going to become widely applicable in sustainable agriculture. Nanotechnology has resulted in a revolution due to large scale production and increasing demand for nanoproducts. In agriculture sector nanotechnology has given huge benefits like fabricated xylem vessels, nanoscale carriers and biosensors. These are examples of biggest inventions in field of nanotechnology which have led to modernization of agriculture sector.
Source: Singh, R. P., Handa, R., & Manchanda, G. (2021). Nanoparticles in sustainable agriculture: An emerging opportunity. Journal of Controlled Release, 329, 1234-1248.
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