hazardous by-products are major environmental concern
while, physical methods have high energy consumption
(Huang et al. 2011). However, much attention is paid
towards the biological synthesis approach, which has many
advantages like eco-friendly nature, reliability, biocompatibility and low production cost (Roy et al. 2013; Emeka et al.
2014). NPs synthesized from plants, microbes and other
biological resources are therefore considered as preferred
way for synthesis of NPs (Khandel and Shahi 2018).
Nanotechnology is progressing rapidly in various fields
due to widespread applications and substantial success.
Nanotechnology seems to be a suitable option for the protection of plants from various agents of biotic stress
(Rodríguez-Cutiño et al. 2018). Recently, interventions of
nanotechnological applications in agriculture sciences have
been studied like preparation of nanoscale fertilizers (Xu
et al. 2015; Jahagirdar et al. 2020), pesticides (Grillo et al.
2016; Adisa et al. 2019), plant disease diagnosis (Prasad
et al. 2017; Chen et al. 2019). It can be stated that agricultural productivity would be increased using better varieties
and crop plant protection. The significant antimicrobial
potential of NPs against plant pathogens has been widely
investigated for advanced agricultural applications (Baker
et al. 2017; Verma et al. 2018; Chen et al. 2019; Fu et al.
2020). Further use of nano-agro-particles is considered as a
valuable alternative against several fungal pathogens. For
instance, Ghasemian et al. (2012) demonstrated the role
of CuNPs to ward off filamentous fungi Penicillium
chrysogenum, Alternaria alternata, Fusarium solani and
Aspergillus flavus. Giannousi et al. (2013) studied the efficacy of three types of copper oxide NPs against Phytophthora infestans, a pathogen for tomato crop. The authors
reported, all the Cu-based NPs, which were tested, showed a
significant inhibitory effect against the tested pathogen
(Giannousi et al. 2013). At the same time, expected massive
usage of NPs in the upcoming future poses serious environmental concerns, and therefore, the interaction of NPs to
the microbes is of utmost necessity to formulate a sustainable release policy of the NPs, taking into these concerns.
2 Main Sink of Nanoparticles, Their
Production, Applications
and Environmental Concerns
The use of NPs raises major concerns for agro-ecosystems,
and the soil and water are considered as their main sink.
Some NPs be present naturally in the environment; however,
the concentrations of these NPs are extremely low with the
negligible impacts (Remedios et al. 2012). If the NPs release
is inevitable, the objective must be to reduce the NPs release,
which might pose a noteworthy threat to agro-ecosystems or
human health (Yadav et al. 2014). Main sinks of NPs, i.e.
NPs in soil and water, are described in detail in later
sections.
2.1 Nanoparticles in Soils
From the starting of the Earth’s history, NPs have naturally
existed, and it is a known fact that they are not human
innovation (Handy et al. 2008). Soils are considered as a
source of natural NPs, as it is a multifaceted matrix with
different colloidal mineral particles. At the same time, the
pollutants immobilization in the soil matrix has a major
concern, which greatly outweighs any anthropogenic production as its exposure to natural NPs (Sharma et al. 2015).
With reference to the techniques of NPs formation, there are
a number of mechanisms that are able to produce NPs in the
environment, like geological and biological. Geological way
of synthesis involves autogenesis, or the neo-formation
found in the soils, physicochemical weathering, as well as
the volcanic explosion activity. Typically, the mentioned
geological processes are capable of producing inorganic
particles, whereas, in biological mechanisms, organic
nano-molecules could be produced, even though some
organisms are capable of yielding in the cell the minerals
granules (Handy et al. 2008).
In the soils, the movement of NPs is explained by
Brownian motion and gravity has no role in this. Consequently, solitary NPs could be entering into micropores and
unless they get absorbed on mobile colloids, the mobility is
greatly improved, while the aggregates of NPs stay remnant
in macropores, while the mobility was introverted, when
they are adsorbed on particles which are non-mobile.
The NPs and the soil molecules attachment are depending
upon collector and the NPs shape as well as onto the diverse
properties, which transform NPs surrounding environment.
Thus, the stipulations of soils are capable of improving or
inhibiting the NPs mobility in soils. The aquifers and the
humic acids present in soils could considerably manipulate
NPs mobility of different metal oxides (Ben-Moshe 2010),
which could persuade NPs composition monitoring and the
soil nutrients fate, contaminants and pollutants as well
(Ben-Moshe 2010; Mura et al. 2013).
A powerful rising significance in the exploitation of NPs
for the various applications for soil is documented in various
researches by several researchers (Pan and Xing 2012; Priester et al. 2012; Jośko and Oleszczuk 2013; Suppan 2013;
Fernández et al. 2014; Garner and Keller 2014; Jośko et al.
2014; Conway et al. 2015; Schaumann et al. 2015a, b;
Watson et al. 2015; Rabbani et al. 2016). Ge et al. (2011)
observed the effects of NPs on bacterial communities’ present in soil, in which reduced biomass, diversity of microbes
and soil enzyme activity is impacted by the action of ZnO
NPs. The aggregation and immobilization of NPs in the soil
176
S. S. Shende et al.
while, physical methods have high energy consumption
(Huang et al. 2011). However, much attention is paid
towards the biological synthesis approach, which has many
advantages like eco-friendly nature, reliability, biocompatibility and low production cost (Roy et al. 2013; Emeka et al.
2014). NPs synthesized from plants, microbes and other
biological resources are therefore considered as preferred
way for synthesis of NPs (Khandel and Shahi 2018).
Nanotechnology is progressing rapidly in various fields
due to widespread applications and substantial success.
Nanotechnology seems to be a suitable option for the protection of plants from various agents of biotic stress
(Rodríguez-Cutiño et al. 2018). Recently, interventions of
nanotechnological applications in agriculture sciences have
been studied like preparation of nanoscale fertilizers (Xu
et al. 2015; Jahagirdar et al. 2020), pesticides (Grillo et al.
2016; Adisa et al. 2019), plant disease diagnosis (Prasad
et al. 2017; Chen et al. 2019). It can be stated that agricultural productivity would be increased using better varieties
and crop plant protection. The significant antimicrobial
potential of NPs against plant pathogens has been widely
investigated for advanced agricultural applications (Baker
et al. 2017; Verma et al. 2018; Chen et al. 2019; Fu et al.
2020). Further use of nano-agro-particles is considered as a
valuable alternative against several fungal pathogens. For
instance, Ghasemian et al. (2012) demonstrated the role
of CuNPs to ward off filamentous fungi Penicillium
chrysogenum, Alternaria alternata, Fusarium solani and
Aspergillus flavus. Giannousi et al. (2013) studied the efficacy of three types of copper oxide NPs against Phytophthora infestans, a pathogen for tomato crop. The authors
reported, all the Cu-based NPs, which were tested, showed a
significant inhibitory effect against the tested pathogen
(Giannousi et al. 2013). At the same time, expected massive
usage of NPs in the upcoming future poses serious environmental concerns, and therefore, the interaction of NPs to
the microbes is of utmost necessity to formulate a sustainable release policy of the NPs, taking into these concerns.
2 Main Sink of Nanoparticles, Their
Production, Applications
and Environmental Concerns
The use of NPs raises major concerns for agro-ecosystems,
and the soil and water are considered as their main sink.
Some NPs be present naturally in the environment; however,
the concentrations of these NPs are extremely low with the
negligible impacts (Remedios et al. 2012). If the NPs release
is inevitable, the objective must be to reduce the NPs release,
which might pose a noteworthy threat to agro-ecosystems or
human health (Yadav et al. 2014). Main sinks of NPs, i.e.
NPs in soil and water, are described in detail in later
sections.
2.1 Nanoparticles in Soils
From the starting of the Earth’s history, NPs have naturally
existed, and it is a known fact that they are not human
innovation (Handy et al. 2008). Soils are considered as a
source of natural NPs, as it is a multifaceted matrix with
different colloidal mineral particles. At the same time, the
pollutants immobilization in the soil matrix has a major
concern, which greatly outweighs any anthropogenic production as its exposure to natural NPs (Sharma et al. 2015).
With reference to the techniques of NPs formation, there are
a number of mechanisms that are able to produce NPs in the
environment, like geological and biological. Geological way
of synthesis involves autogenesis, or the neo-formation
found in the soils, physicochemical weathering, as well as
the volcanic explosion activity. Typically, the mentioned
geological processes are capable of producing inorganic
particles, whereas, in biological mechanisms, organic
nano-molecules could be produced, even though some
organisms are capable of yielding in the cell the minerals
granules (Handy et al. 2008).
In the soils, the movement of NPs is explained by
Brownian motion and gravity has no role in this. Consequently, solitary NPs could be entering into micropores and
unless they get absorbed on mobile colloids, the mobility is
greatly improved, while the aggregates of NPs stay remnant
in macropores, while the mobility was introverted, when
they are adsorbed on particles which are non-mobile.
The NPs and the soil molecules attachment are depending
upon collector and the NPs shape as well as onto the diverse
properties, which transform NPs surrounding environment.
Thus, the stipulations of soils are capable of improving or
inhibiting the NPs mobility in soils. The aquifers and the
humic acids present in soils could considerably manipulate
NPs mobility of different metal oxides (Ben-Moshe 2010),
which could persuade NPs composition monitoring and the
soil nutrients fate, contaminants and pollutants as well
(Ben-Moshe 2010; Mura et al. 2013).
A powerful rising significance in the exploitation of NPs
for the various applications for soil is documented in various
researches by several researchers (Pan and Xing 2012; Priester et al. 2012; Jośko and Oleszczuk 2013; Suppan 2013;
Fernández et al. 2014; Garner and Keller 2014; Jośko et al.
2014; Conway et al. 2015; Schaumann et al. 2015a, b;
Watson et al. 2015; Rabbani et al. 2016). Ge et al. (2011)
observed the effects of NPs on bacterial communities’ present in soil, in which reduced biomass, diversity of microbes
and soil enzyme activity is impacted by the action of ZnO
NPs. The aggregation and immobilization of NPs in the soil
176
S. S. Shende et al.