In conjugation with silver NPs, ZnO and CuO NPs were
used for suppressing soil-borne diseases in Prunus domestica (Malandrakis et al. 2019). Al 2 O 3 NPs were used to
control root rot in Solanum lycopersicum (Shenashen et al.
2017). Silver NPs were used to protect Vigna unguiculata
from disease attack (Vanti et al. 2019). CuO NPs were used
to protect Solanum lycopersicum from late blight disease
caused because of Phytophthora infestans (Giannousi et al.
2013). MgO NPs were applied to Solanum lycopersicum to
suppress pathogens like Ralstonia solanacearum (Imada
et al. 2016). Interestingly, NMs like ZnO and MgO possess
antimicrobial properties, smooth and optically transparent
and are easily dispensable, which increases their demand for
agricultural purposes and preservatives (Aruoja et al. 2009;
Sharma et al. 2009). Further, deoxyribonucleic acid
(DNA) and chemicals could be easily delivered to the plant
cells by silica NPs, modifying the genetic composition of the
cells to initiate defence mechanism against any pathogen
attack (Torney et al. 2007).
Nanomaterials have been used as nanosensors to measure
and monitor disease prevalence in crops. Nanosensors could
provide timely detection of pest attack by early identification
of symptoms to protect crops from diseases and increase
crop yield. Wireless sensors were developed to detect insect
attack (Afsharinejad et al. 2016). Nano-Au-based sensors
have been reported to be efficient in detection of a fungal
disease named Karnal bunt in Triticum aestivum (Singh et al.
2010). Interestingly, protection of crops from diseases might
help in decreasing the utilization of agrochemicals and
enhancing crop yield, thereby boosting the national economy (González-Fernández et al. 2010; Rai and Ingle 2012).
3 Seed Germination and Plant Growth
Germination of a seed could be considered the most critical
and sensitive stage in a plant life. It enables seedling growth,
the development of which establishes a plant. Seed germination could be altered by various factors including soil
fertility, moisture content, genetics and environmental factors (Manjaiah et al. 2018). NMs have been reported to
facilitate seed germination, thereby promoting plant growth.
The role of NMs in seed germination is not explained very
well so far. It has been reported that NMs enable seed coat
penetration, activate enzymes and enhance water absorption
and usage, which result in improved seed germination and
seedling growth (Changmei et al. 2002; Khodakovskaya
et al. 2012a; Banerjee and Kole 2016). Additionally, water
retention uplifts root growth (Shojaei et al. 2018). However,
the mechanism behind water uptake is unclear.
Carbon nanotubes (CNTs) have a beneficial effect on
germination of seeds in a number of plants such as Triticum
aestivum (wheat), Lycopersicon esculentum (tomato), Zea
mays (maize), Arachis hypogaea (peanut), Allium sativum
(garlic), Glycine max (soybean) and Hordeum vulgare
(barley) (Khodakovskaya et al. 2012a; Lahiani et al. 2013;
Joshi et al. 2018). Low concentrations of multiwalled CNTs
have been reported in augmenting growth by 60% in tobacco
plants (Bheemidi 2011; Khodakovskaya et al. 2012b; Suresh
et al. 2013; Gottschalk et al. 2015). Zeolite, silicon oxide and
titanium oxide NMs have been reported to facilitate seed
germination in plants (Changmei et al. 2002; Manjaiah et al.
2018). Iron/silicon oxide NMs were reported to promote
seed germination in Zea mays and Hordeum vulgare (Najafi
Disfani et al. 2017). FeS 2 has been noted to enhance germination in chick pea, spinach, mustard and sesame (Srivastava et al. 2014; Das et al. 2016). Fullerenes have been
stated to stimulate cell division, thereby increasing the
hypocotyl growth in Arabidopsis (Gao et al. 2011). Fullerols
escalate fruit quality and quantity, double the crop yield and
revitalize bioactive components like lycopene as observed in
Momordica charantia (Kole et al. 2013). Kaolin NPs have
been stated to enable seed growth and strengthen roots
(Gogos et al. 2012).
Zinc and boron as NMs have shown to enrich fruit quality
and quantity, without altering fruit properties (Davarpanah
et al. 2016). Hydroxyapatite NM-coated fertilizers facilitate
slow release of nutrients for the crops to consume in the
longer run (Lateef et al. 2016; Madusanka et al. 2017). NMs
have been reported to boost photosynthesis levels. A 2.5%
application of nano-titanium oxide increased the photosynthetic activity (Zheng et al. 2005). Nano-iron/silicon oxide
boosted shoot length in Hordeum vulgare and Zea mays
seedlings when the application rate was 15 mg/kg (Najafi
Disfani et al. 2017). Interestingly, NM application rate is
very important with regards to increasing crop production.
Application rate of 25 mg/kg had negative impact on Hordeum vulgare and Zea mays seedlings (Najafi Disfani et al.
2017). Further, mode of NM application is also critical for
crop productivity enhancement. For example, foliar application of nano-magnetite is preferable to soil application to
boost overall plant growth in Ocimum basilicum (Elfeky
et al. 2013).
4 Photosynthetic Upgradation
Research has been focussed upon catalyzing photosynthetic
upgradation by increasing RuBisCO efficiency, engineering
C 3 plants for manoeuvring C 4 pathway, bringing changes in
chlorophyll efficacy and enhancing photosynthetic waveband (Hibberd et al. 1996; Amthor 2001; Evans 2013). NMs
have been reported to favour photosynthesis. Integration of
plants and NMs is referred to as plant nanobionics. TiO 2 NPs
were reported to stimulate photocatalytic activity by
improving the light absorbed by the leaves. Further, TiO 2
Nanotechnology for Sustainable Crop Production …
33
used for suppressing soil-borne diseases in Prunus domestica (Malandrakis et al. 2019). Al 2 O 3 NPs were used to
control root rot in Solanum lycopersicum (Shenashen et al.
2017). Silver NPs were used to protect Vigna unguiculata
from disease attack (Vanti et al. 2019). CuO NPs were used
to protect Solanum lycopersicum from late blight disease
caused because of Phytophthora infestans (Giannousi et al.
2013). MgO NPs were applied to Solanum lycopersicum to
suppress pathogens like Ralstonia solanacearum (Imada
et al. 2016). Interestingly, NMs like ZnO and MgO possess
antimicrobial properties, smooth and optically transparent
and are easily dispensable, which increases their demand for
agricultural purposes and preservatives (Aruoja et al. 2009;
Sharma et al. 2009). Further, deoxyribonucleic acid
(DNA) and chemicals could be easily delivered to the plant
cells by silica NPs, modifying the genetic composition of the
cells to initiate defence mechanism against any pathogen
attack (Torney et al. 2007).
Nanomaterials have been used as nanosensors to measure
and monitor disease prevalence in crops. Nanosensors could
provide timely detection of pest attack by early identification
of symptoms to protect crops from diseases and increase
crop yield. Wireless sensors were developed to detect insect
attack (Afsharinejad et al. 2016). Nano-Au-based sensors
have been reported to be efficient in detection of a fungal
disease named Karnal bunt in Triticum aestivum (Singh et al.
2010). Interestingly, protection of crops from diseases might
help in decreasing the utilization of agrochemicals and
enhancing crop yield, thereby boosting the national economy (González-Fernández et al. 2010; Rai and Ingle 2012).
3 Seed Germination and Plant Growth
Germination of a seed could be considered the most critical
and sensitive stage in a plant life. It enables seedling growth,
the development of which establishes a plant. Seed germination could be altered by various factors including soil
fertility, moisture content, genetics and environmental factors (Manjaiah et al. 2018). NMs have been reported to
facilitate seed germination, thereby promoting plant growth.
The role of NMs in seed germination is not explained very
well so far. It has been reported that NMs enable seed coat
penetration, activate enzymes and enhance water absorption
and usage, which result in improved seed germination and
seedling growth (Changmei et al. 2002; Khodakovskaya
et al. 2012a; Banerjee and Kole 2016). Additionally, water
retention uplifts root growth (Shojaei et al. 2018). However,
the mechanism behind water uptake is unclear.
Carbon nanotubes (CNTs) have a beneficial effect on
germination of seeds in a number of plants such as Triticum
aestivum (wheat), Lycopersicon esculentum (tomato), Zea
mays (maize), Arachis hypogaea (peanut), Allium sativum
(garlic), Glycine max (soybean) and Hordeum vulgare
(barley) (Khodakovskaya et al. 2012a; Lahiani et al. 2013;
Joshi et al. 2018). Low concentrations of multiwalled CNTs
have been reported in augmenting growth by 60% in tobacco
plants (Bheemidi 2011; Khodakovskaya et al. 2012b; Suresh
et al. 2013; Gottschalk et al. 2015). Zeolite, silicon oxide and
titanium oxide NMs have been reported to facilitate seed
germination in plants (Changmei et al. 2002; Manjaiah et al.
2018). Iron/silicon oxide NMs were reported to promote
seed germination in Zea mays and Hordeum vulgare (Najafi
Disfani et al. 2017). FeS 2 has been noted to enhance germination in chick pea, spinach, mustard and sesame (Srivastava et al. 2014; Das et al. 2016). Fullerenes have been
stated to stimulate cell division, thereby increasing the
hypocotyl growth in Arabidopsis (Gao et al. 2011). Fullerols
escalate fruit quality and quantity, double the crop yield and
revitalize bioactive components like lycopene as observed in
Momordica charantia (Kole et al. 2013). Kaolin NPs have
been stated to enable seed growth and strengthen roots
(Gogos et al. 2012).
Zinc and boron as NMs have shown to enrich fruit quality
and quantity, without altering fruit properties (Davarpanah
et al. 2016). Hydroxyapatite NM-coated fertilizers facilitate
slow release of nutrients for the crops to consume in the
longer run (Lateef et al. 2016; Madusanka et al. 2017). NMs
have been reported to boost photosynthesis levels. A 2.5%
application of nano-titanium oxide increased the photosynthetic activity (Zheng et al. 2005). Nano-iron/silicon oxide
boosted shoot length in Hordeum vulgare and Zea mays
seedlings when the application rate was 15 mg/kg (Najafi
Disfani et al. 2017). Interestingly, NM application rate is
very important with regards to increasing crop production.
Application rate of 25 mg/kg had negative impact on Hordeum vulgare and Zea mays seedlings (Najafi Disfani et al.
2017). Further, mode of NM application is also critical for
crop productivity enhancement. For example, foliar application of nano-magnetite is preferable to soil application to
boost overall plant growth in Ocimum basilicum (Elfeky
et al. 2013).
4 Photosynthetic Upgradation
Research has been focussed upon catalyzing photosynthetic
upgradation by increasing RuBisCO efficiency, engineering
C 3 plants for manoeuvring C 4 pathway, bringing changes in
chlorophyll efficacy and enhancing photosynthetic waveband (Hibberd et al. 1996; Amthor 2001; Evans 2013). NMs
have been reported to favour photosynthesis. Integration of
plants and NMs is referred to as plant nanobionics. TiO 2 NPs
were reported to stimulate photocatalytic activity by
improving the light absorbed by the leaves. Further, TiO 2
Nanotechnology for Sustainable Crop Production …
33