Agriculture Reference
In-Depth Information
Fig. 11.13
Effect of nanoanatase TiO
2
on the growth of spinach. The picture was taken after four
weeks of cultivation. Lane 1 Control, lane 2 treated with bulk-TiO
2
, lane 3 treated with nano TiO
2
(anatase). (Adopted with kind permission from Linglan et al.
2008
)
reduction and oxygen evolution. Furthermore, noncyclic photophosphorylation ac-
tivity was higher than that of cyclic photophosphorylation activity. The possible rea-
son, according to author, could be due to the penetration of TiO
2
nanoparticles into
the chloroplast and their oxidation-reduction reactions which accelerate electron
transport and oxygen evolution. TiO
2
nanoparticles (anatase) have also been found
to induce spinach seed germination and plant growth (Fig.
11.13
) by regulating the
germination of aged seeds and their vigor indexes (Linglan et al.
2008
; Yang et al.
2006
). An increase of these indexes was observed at 0.25-4 % TiO
2
nanoparticles
treatments. Furthermore, it was observed that during the growth stage, the presence
of TiO
2
nanoparticles increased the dry weight, chlorophyll synthesis, and metabo-
lism in photosynthetic organisms. These results confirmed that the nanometer-size
particles have remarkable effects on physiological processes. These positive effects
are assumed to be due to the antimicrobial properties of nanoparticles, which in turn
can increase strength and resistance of plants to stress. Additionally, nanoparticles
could also sequester nutrients on their surfaces and thus serve as a nutrient stock to
the organisms, especially those nanoparticles having high specific surface area. The
authors also reported that the effects of bulk-TiO
2
particles were not significant.
In another report, it was shown that TiO
2
nanoparticles (anatase) improved plant
growth by enhanced nitrogen metabolism (Yang et al.
2007
) which promotes the ab-
sorption of nitrate in spinach, and helps in accelerating the conversion of inorganic
nitrogen into organic nitrogen, consequently increasing the fresh and dry weights.
Other studies also showed the effects of nitrogen photoreduction on the improved
growth of treated spinach plant (Mingyu et al.
2007
). It has also been reported that
