257
NPs also increased the enzymatic activity of antioxidant enzymes, catalase, and
ascorbate peroxidase (Morales et al. 2013).
Polyhyroxyl fullerenes were documented to positively regulate the growth of
A. thaliana, Apergillus niger, and Ceriodaphnia dubia. Increment in lifespan and
reproduction efficiency of C. dubia and the vegetative growth parameters of A. thaliana like enhanced length of hypocotyls were noticed on fullerene exposure (Gao
et al. 2011).
Interestingly, NP exposure has been reported to enhance the content of medicinally important phytochemicals. Carbon NPs and fullerols were also found to
enhance the growth, metabolism, and yield of bitter melon plants. Exposure of fullerols to bitter melon seeds has increased their vegetative biomass and relative water
content. Further, increment in the number of fruits, fruit length, and fruit weight
enhanced their overall yield. Accumulation of anticancerous metabolites, that is,
cucurbitacin-B and lycopene, was also significantly increased. Additionally, increment in the content of antidiabetic metabolites, charantin and insulin, was also evident (Kole et al. 2013).
PEG and carbon-coated silver (Ag) NPs were observed to stimulate the growth
of A. thaliana and poplar plants. Large-sized Ag NPs were phytostimulatory
whereas small-sized Ag NPs induced toxicity to plants. On the other hand, Ag
+
ions
were inducing stress and inhibiting their growth. Ag NPs of 25 nm were enhancing
the root growth, biomass accumulation, and transpiration of both plants (Wang et al.
2013b). Application of root ash NPs to cucumber plants was found to enhance the
shoot and root biomass (Moghaddasi et al. 2015). Foliar spray of gold (Au) NPs to
Brassica juncea in field trials was found to enhance their vegetative growth. An
increase in the number of leaves, branches, pods, and enhancement in their stem
height and diameter was noticed. An overall increase in the yield of plants was also
noticed (Arora et al. 2012). Similarly, exposure of Au NPs through Murashige and
Skoog medium enhanced the vegetative growth and seed yield of A. thaliana plants
(Kumar et al. 2013).
Exposure of CeO 2 NPs was found to reduce the seed germination and root–shoot
length of radish seedlings. Modification of CeO 2 NPs with citric acid was found to
enhance the root biomass and fresh water content of the treated seedlings (TrujilloReyes et al. 2013). Tetramethylammonium hydroxide-coated ferrophase magnetic
NP exposure has growth-enhancing effect on maize plants (Racuciu and Creanga
2007). Citric acid-capped CeO 2 NPs increased the root biomass in radish (Raphanus
sativus). Bare NPs, however, were toxic and induced reduction in root elongation
and stem biomass (Trujillo-Reyes et al. 2013). CeO 2 NPs increased the biomass of
kidney beans (Majumdar et al. 2014). TiO 2 NP treatment has induced plant growth
enhancement in spinach. TiO 2 NP exposure has been reported to enhance the fresh
weight, dry weight content, and overall growth of spinach plants (Gao et al. 2006;
Yang et al. 2006; Linglan et al. 2008). TiO 2 NP exposure can overcome the nitrogen
deficiency in spinach. Spinach plants showed nitrogen deficiency symptoms, chlorosis, when grown in N-deficient Hoagland solution. However, TiO 2 NP-treated
spinach plants grown in nitrogen-deficient Hoagland solution showed normal
growth compared to control plants (Yang et al. 2007).
10 Phytoresponse to Nanoparticle Exposure
NPs also increased the enzymatic activity of antioxidant enzymes, catalase, and
ascorbate peroxidase (Morales et al. 2013).
Polyhyroxyl fullerenes were documented to positively regulate the growth of
A. thaliana, Apergillus niger, and Ceriodaphnia dubia. Increment in lifespan and
reproduction efficiency of C. dubia and the vegetative growth parameters of A. thaliana like enhanced length of hypocotyls were noticed on fullerene exposure (Gao
et al. 2011).
Interestingly, NP exposure has been reported to enhance the content of medicinally important phytochemicals. Carbon NPs and fullerols were also found to
enhance the growth, metabolism, and yield of bitter melon plants. Exposure of fullerols to bitter melon seeds has increased their vegetative biomass and relative water
content. Further, increment in the number of fruits, fruit length, and fruit weight
enhanced their overall yield. Accumulation of anticancerous metabolites, that is,
cucurbitacin-B and lycopene, was also significantly increased. Additionally, increment in the content of antidiabetic metabolites, charantin and insulin, was also evident (Kole et al. 2013).
PEG and carbon-coated silver (Ag) NPs were observed to stimulate the growth
of A. thaliana and poplar plants. Large-sized Ag NPs were phytostimulatory
whereas small-sized Ag NPs induced toxicity to plants. On the other hand, Ag
+
ions
were inducing stress and inhibiting their growth. Ag NPs of 25 nm were enhancing
the root growth, biomass accumulation, and transpiration of both plants (Wang et al.
2013b). Application of root ash NPs to cucumber plants was found to enhance the
shoot and root biomass (Moghaddasi et al. 2015). Foliar spray of gold (Au) NPs to
Brassica juncea in field trials was found to enhance their vegetative growth. An
increase in the number of leaves, branches, pods, and enhancement in their stem
height and diameter was noticed. An overall increase in the yield of plants was also
noticed (Arora et al. 2012). Similarly, exposure of Au NPs through Murashige and
Skoog medium enhanced the vegetative growth and seed yield of A. thaliana plants
(Kumar et al. 2013).
Exposure of CeO 2 NPs was found to reduce the seed germination and root–shoot
length of radish seedlings. Modification of CeO 2 NPs with citric acid was found to
enhance the root biomass and fresh water content of the treated seedlings (TrujilloReyes et al. 2013). Tetramethylammonium hydroxide-coated ferrophase magnetic
NP exposure has growth-enhancing effect on maize plants (Racuciu and Creanga
2007). Citric acid-capped CeO 2 NPs increased the root biomass in radish (Raphanus
sativus). Bare NPs, however, were toxic and induced reduction in root elongation
and stem biomass (Trujillo-Reyes et al. 2013). CeO 2 NPs increased the biomass of
kidney beans (Majumdar et al. 2014). TiO 2 NP treatment has induced plant growth
enhancement in spinach. TiO 2 NP exposure has been reported to enhance the fresh
weight, dry weight content, and overall growth of spinach plants (Gao et al. 2006;
Yang et al. 2006; Linglan et al. 2008). TiO 2 NP exposure can overcome the nitrogen
deficiency in spinach. Spinach plants showed nitrogen deficiency symptoms, chlorosis, when grown in N-deficient Hoagland solution. However, TiO 2 NP-treated
spinach plants grown in nitrogen-deficient Hoagland solution showed normal
growth compared to control plants (Yang et al. 2007).
10 Phytoresponse to Nanoparticle Exposure