Agriculture Reference
In-Depth Information
average diameter of 20 nm, applied onto the roots of
Oryza sativa
, revealed the
deposition of nanoparticles inside the root cells damaging cells and vacuoles by
penetration through small pores of the cell walls. This reveals an important effect of
silver nanoparticles inside cells related to periods of phytotoxicity (Mazumdar and
Ahmed
2011
). The environmental toxicity of silver nanoparticles at different
particle sizes was evaluated using seed germination tests with ryegrass, barley,
and flax exposed to different concentrations of metallic nanoparticles. Interestingly,
no effect was observed for colloidal silver nanoparticles (5 and 20 nm) up to 10 and
20 mg L
1
, respectively (El-Temsah and Joner
2010
). Similarly,
Phaseolus
radiatus
, in the agar test, showed only 35 % inhibition in the seedling; however,
in a soil test, no effects on shoots, roots, and seedlings were observed up to 150 mg/
kg of soil. EC50 of silver nanoparticles on
P. radiatus
and
Sorghum bicolor
in the
agar test gave values of 13 and 26 mg L
1
, respectively (Lee et al.
2012
). Silver
nanoparticles exhibited a broad spectrum of antimicrobial activities against plant
diseases caused by fungal pathogens. However, high concentrations of silver
nanoparticles damaged tested plants, such as exemplified in cucumber leaves and
pansy flowers (Park et al.
2006
). Silver nanoparticles can be used for control of
sclerotium-forming plant pathogenic fungi (Min et al.
2009
). It is known that silver
nanoparticles interacted with fungal hyphae causing severe damage due to the
separation of layers of hyphal wall and collapse of hyphae (Nair et al.
2010
). Silver
nanoparticles on
Raffaela
fungus also caused a detrimental effect. This fungus is
important since it is responsible for causing the mortality of oak trees acting on
conidial germination (Kim et al.
2009
). Gerbera flower
s lifetime was enhanced
upon treating with silver nanoparticles, due to the inhibition of microbial growth
and reduction of vascular blockage. This process led to an increase in water uptake
by the plant and thereby maintaining the turgidity of the cells of flowers (Solgi
et al.
2009
; Liu et al.
2009a
).
Indeed, silver nanoparticles can act as NO donor vehicles for several appli-
cations, and it was published as an invention that included at least one NO donor in
combination with a second therapeutically active agent, e.g., silver nanoparticles,
for antimicrobial and wound healing applications (Schoenfisch et al.
2009
).
'
9.3.7.4 Gold Nanoparticles
Gold nanoparticles (with diameters of 3.5 nm) are able to penetrate into plant
tissues through roots and move into the vascular system of tobacco plants (
Nicoti-
ana xanthi
) producing leaf necrosis after long exposure of plants to these
nanoparticles. This work showed the potential of gold nanoparticles to penetrate
plant tissues through size-dependent mechanisms and translocation to cells and
tissues, leading to biotoxicity upon long exposure (Sabo-Attwood et al.
2011
).
Citrate-stabilized gold nanoparticles, in the presence of
S
-nitrosothiols, the -S-
NO bond breaks, thereby releasing NO and modifying the gold nanoparticle surface
with the corresponding thiol. This association allows for surface-controlled NO
release that is proportional to the number of thiols bound to the gold nanoparticle
