Agriculture Reference
In-Depth Information
4.6 Nano-fertilizers and Plant Growth
Although most of the recent studies have emphasized the adverse effects of
nanoparticles on plants (Lin and Xing
2007
; Lee et al.
2008
; Barrena et al.
2009
),
a few studies have suggested that nanoparticles delivered at safe dose may help in
promoting plant growth and overall yield (Zheng et al.
2005
; Gao et al.
2006
;
L
opez-Moreno et al.
2010
). Multi-walled carbon nanotubes (MWCNTs) have been
reported to have the ability to increase the seed germination and growth of tomato
and to enhance the growth in tobacco cells (Khodakovskaya et al.
2009
,
2012
).
Mondal et al. (
2011
) reported the enhancement of seed germination and plant
growth using MWCNTs in mustard plant. On the basis of germination index and
relative root elongation, they showed that oxidized MWCNTs were more effective
at lower concentration than the non-oxidized MWCNTs. Sahandi et al. (
2011
)
reported that nanosilver is better than silver nitrate in improving the seed yield
and preventing leaf abscission in borage plant. The plant hormone, ethylene plays a
key role in leaf abscission, and silver ions have been shown to inhibit ethylene by
replacing copper ions from the receptors. Employing the foliar spray method, both
nanosilver and silver nitrate were sprayed on different sets of plants, and it was
observed that nanosilver was effective at a lower concentration than silver nitrate.
Effect of biosynthesized silver nanoparticles on emergence of seedling and various
plant growth parameters of many economically important plant species were
studied by Namasivayam and Chitrakala (
2011
).
Mahajan et al. (
2011
) used the agar plate method to test the effect of ZnO
nanoparticles on the growth of
Vigna radiata
and
Cicer arietinum
. Evidence of
nanoparticles adsorbed on the root surface was provided using correlative light and
scanning electron microscopy. Inductively coupled plasma/atomic emission spec-
troscopy (ICP-AES) studies revealed the absorption of ZnO nanoparticles by
seedlings. Using the foliar spray method, Burman et al. (
2013
) studied the effect
of ZnO nanoparticles on growth and antioxidant system of chickpea seedlings.
They found that lower concentration (1.5 ppm) of ZnO nanoparticles has positive
effect on chickpea seedling growth. Moreover, seedlings treated with ZnO
nanoparticles showed improved biomass accumulation which may be due to
lower reactive oxygen species (ROS) levels as evident from lower malondialdehyde
(MDA) content. Similarly, Prasad et al. (
2012
) observed that treatment of nano zinc
at lower concentration (1,000 ppm) had positive effects on plant, but it showed
toxicity symptoms at higher concentration (2,000 ppm) pointing out their meticu-
lous use. Further, during field experiments, they reported usage of 15 times lower
dose of ZnO nanoparticles compared to the recommended dose of ZnSO
4
and
recorded 29.5 % higher pod yield. Likewise, ZnO nanoparticles showed root
elongation in
Glycine max
at 500 ppm concentration but reduction in size at higher
concentration of ZnO (Lopez-Moreno et al.
2010
). A study aimed to investigate the
effects of ZnO and CeO
2
nanoparticles (400 ppm) on
Cucumis sativus
fruit quality
showed that both the tested nanoparticles resulted in increased starch content and
could alter the carbohydrate pattern (Zhao et al.
2014
).
