bundles. Some nanoparticles, viz. TiO 2 , ZnO, silica NPs (SiO 2 NPs) are transported
inside the cells via endocytosis or pores or channels. Nanofertilizer application
allows better dissolution and faster absorption/assimilation of essential elements
(N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, and Mo) by the plant. The nanoparticles penetrate
via cuticle and reach tissues of the plants. This allows their slow and effective release
to the target area. Encapsulation of microorganisms such as bacteria or fungi
improves plant root health by increasing the availability of nitrogen, phosphorus,
potassium in the root zone. Large surface area and small particle size (less than the
pore size of root and leaves) of nanofertilizer increase their penetration into the plant,
improve nutrient uptake and use efficiency. Reduced particle size results in increased
specific surface area which provides more interaction of nanofertilizers resulting in
more penetration and uptake of the nutrients.
Application of nanotechnology to seed priming technique increases plant’s
capacity for stress tolerance. Seeds imbibed or encapsulated with nanoparticles
having specific bacterial strain are termed as smart seeds. Coating seeds with nano
membrane shows efficiency in sensing the availability of water allowing the fast
germination of seeds. Silver NPs induce positive responses in production of roots
(long root). This occurs via inhibition of ethylene synthesis. Application of carbon
nanotubes improved seed germination in tomato by enhancing moisture permeation
(Cañas et al. 2008; Khodakovskaya et al. 2009). Carbon nanotubes (CNTs) act as a
passage and channelize the water from the substrate into the seeds through pores
present in the seed coat.
Nanoparticles exert negative effects on the plant growth if the doses applied
exceed the optimum requirement. High concentrations reduce growth and yield of
the crops. Application of Zn nanoparticles at doses such as 50 ppm of ZnSO 4 ,
100 ppm of DTPA-Zn, and 25 ppm of NfsOZn leads to an increase in biomass
production and nitrogen assimilation but ZnO nanoparticles at concentrations above
25 ppm have shown negative effect on the root growth of garlic (Allium sativum).
High concentrations of ZnO NPs (200–300 mg/l) induced reduction in chlorophyll
concentration and photosynthetic rate resulting production of less biomass.
Nanoparticles affect the soil microorganisms directly or indirectly by bringing
modifications in the radical exudates of plants. The change in the population, profile,
or biodiversity of microbial symbionts has been noted in response to application of
nanoparticles. Studies have indicated that application of Ag nanoparticles in the
range of 0.1–10 mg/kg exerts negative effect on the microbial growth. Decreased
colonization of roots by mycorrhizal fungi has been noted in soil exposed to low
concentrations of Ag 2 S (1 mg/kg). Negative effects on plant biomass and the
inhibition in the microbial community have been noted in response to treatment of
soil with Ag at the rate 100 mg/kg. Rate of Ag NPs at the concentration of 0.1 mg/kg
has shown to exert toxic effect on soil (He et al. 2013). In contrast positive effect on
soil bacteria has been reported after treatment of soil with FeO at the rate of 1–10 mg/
kg.
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B. Dhir
inside the cells via endocytosis or pores or channels. Nanofertilizer application
allows better dissolution and faster absorption/assimilation of essential elements
(N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, and Mo) by the plant. The nanoparticles penetrate
via cuticle and reach tissues of the plants. This allows their slow and effective release
to the target area. Encapsulation of microorganisms such as bacteria or fungi
improves plant root health by increasing the availability of nitrogen, phosphorus,
potassium in the root zone. Large surface area and small particle size (less than the
pore size of root and leaves) of nanofertilizer increase their penetration into the plant,
improve nutrient uptake and use efficiency. Reduced particle size results in increased
specific surface area which provides more interaction of nanofertilizers resulting in
more penetration and uptake of the nutrients.
Application of nanotechnology to seed priming technique increases plant’s
capacity for stress tolerance. Seeds imbibed or encapsulated with nanoparticles
having specific bacterial strain are termed as smart seeds. Coating seeds with nano
membrane shows efficiency in sensing the availability of water allowing the fast
germination of seeds. Silver NPs induce positive responses in production of roots
(long root). This occurs via inhibition of ethylene synthesis. Application of carbon
nanotubes improved seed germination in tomato by enhancing moisture permeation
(Cañas et al. 2008; Khodakovskaya et al. 2009). Carbon nanotubes (CNTs) act as a
passage and channelize the water from the substrate into the seeds through pores
present in the seed coat.
Nanoparticles exert negative effects on the plant growth if the doses applied
exceed the optimum requirement. High concentrations reduce growth and yield of
the crops. Application of Zn nanoparticles at doses such as 50 ppm of ZnSO 4 ,
100 ppm of DTPA-Zn, and 25 ppm of NfsOZn leads to an increase in biomass
production and nitrogen assimilation but ZnO nanoparticles at concentrations above
25 ppm have shown negative effect on the root growth of garlic (Allium sativum).
High concentrations of ZnO NPs (200–300 mg/l) induced reduction in chlorophyll
concentration and photosynthetic rate resulting production of less biomass.
Nanoparticles affect the soil microorganisms directly or indirectly by bringing
modifications in the radical exudates of plants. The change in the population, profile,
or biodiversity of microbial symbionts has been noted in response to application of
nanoparticles. Studies have indicated that application of Ag nanoparticles in the
range of 0.1–10 mg/kg exerts negative effect on the microbial growth. Decreased
colonization of roots by mycorrhizal fungi has been noted in soil exposed to low
concentrations of Ag 2 S (1 mg/kg). Negative effects on plant biomass and the
inhibition in the microbial community have been noted in response to treatment of
soil with Ag at the rate 100 mg/kg. Rate of Ag NPs at the concentration of 0.1 mg/kg
has shown to exert toxic effect on soil (He et al. 2013). In contrast positive effect on
soil bacteria has been reported after treatment of soil with FeO at the rate of 1–10 mg/
kg.
234
B. Dhir