Agriculture Reference
In-Depth Information
disinfectant as compared to chlorine and ozone. Since TiO
2
is harmless, it is ap-
proved for use in food products up to 1 % of product final weight. TiO
2
photo-
catalyst technique has great potential in various agricultural applications, including
plant protection since it does not form toxic and dangerous compounds and pos-
sesses great pathogen disinfection efficiency. Scientists have been trying to improve
the phytopathogenic disinfection efficiency of TiO
2
thin films by dye doping and
other suitable methods (Yao et al.
2007
). Several research papers have already re-
ported the positive effects of nano-TiO
2
on the germination and growth of spinach
seeds. Nano-anatase TiO
2
enhances plant growth by increased nitrogen metabolism,
improved light absorbance and enhanced activity of Rubisco activase and light har-
vesting complex II, thus promoting accelerated spinach growth (Zheng et al.
2005
;
Gao et al.
2006
; Lei et al.
2007a
,
b
). It was reported that the application of TiO
2
reduced the effects of
Curvularia
leaf spot and bacterial leaf blight in rice and maize
plants and also decreased the incidence and severity of rice blast disease and tomato
spray molds (Chao et al. 2005). TiO
2
plays the function of antibiotics in
Vigna un-
giculata
Walp (cowpea) production in cowpea. Field trials conducted at the Insti-
tute of Agricultural Research and Training, Ibadan, Nigeria, evaluated the effects of
TiO
2
on the development, yield and foliar and pod diseases of cowpea. There was an
increase in the yield of cowpea, and the incidence and severity of
Cercospora
leaf
spot and brown blotch disease got reduced on the application of TiO
2
and best re-
sults were obtained with two sprays of TiO
2
at 125 cc ha
-1
. Hence, nano-TiO
2
could
be successfully used for controlling various diseases in cowpea plant (Owolade
and Ogunleti
2008
). The effects of nano-TiO
2
semiconductor sol (nano-TiO
2
sol,
with an average size of 30.6 nm) in controlling plant pathogenic bacteria;
Pseudo-
monas syringae pv lachrymans
and
Xanthomonas vesicatoria
infecting cucumber
plants were studied (Zhang et al.
2007
), and both artificial inoculation experiment
and field experiments showed that spraying cucumber leaves with nano-TiO
2
sol
controlled phytopathogenic bacteria by forming adhesive and transparent film on
leaf surfaces, thus controlling bacterial angular spot and downy mildew diseases of
cucumber. Hence, nano-TiO
2
could be successfully used as environment-friendly
fungicide and/or bactericide thus preventing and inhibiting various fungal and bac-
terial diseases in plants.
3.4 Carbon Nanomaterials
Among the various engineered nanomaterials, carbon based nanomaterials (such
as single walled carbon nanotubes (SWCNTs), multi walled carbon nanotubes
(MWCNTs), buckyballs, graphene, etc.), occupy a prominent position in various
nano-biotechnology applications. Increased use and exposure to carbon nanoma-
terials could cause environmental concerns. Hence, it is extremely important to
systematically study the effects that carbon nanomaterials have in plants, which
occupy a major component of the food chain. Recently, researchers reported the
effects of MWCNTs of different concentration on the germination and growth of
