Bionanotechnology Applications in Plants and Agriculture - Bionanotechnology: Global Prospects - page 524

2.5

Control
Activated carbon
MWCNT

A

A

2.0

1.5

B

1.0

51.2×??85

0.5

0.0

0 4 8

Days of Exposure

12 16

FIGURE 26.3
Effect.of.bulk.carbon.(activated.carbon).vs..multiwall.carbon.nanotubes.(MWNTs).on.growth.of.zucchini.seed-
lings. in. batch. hydroponic. assays.. MWNTs. (1. mg/ml). were. added. to. 4-day-old. seedlings. in. 25%. Hoagland.
solution.under.controlled.conditions.and.weight.was.monitored.daily.for.15.days..(Reprinted.from.Stampoulis,.
D.,. et. al.,. Environmental Science and Technology ,. 43(24),. 9473,. 2009.. With. permission. of. the. American. Chemical.
Society.)

nanotubes. vs.. activated. carbon. on. total. biomass. of. zucchini. seedlings. was. evaluated..
Generally,. the. data. seem. to. indicate. that. carbon. nanotubes. retard. zucchini. seedling.
growth..Interestingly,.this.result.contrasts.with.carbon.nanotube.studies.in.tomato,.which.
is.discussed.in.Section.26.4.

26.3.1 Nanoparticle Titanium Dioxide

The.effects.of.nano-.and.non-nano-TiO 2 .in.various.forms.were.studied.with.aged.spinach.
seed,.and.signiicant.effects.on.plant.growth.were.observed..It.was.shown.that.the.physi-
ological.effects.are.related.to.the.nanometer-size.particles.at.a.0.25%-4.0%.concentration..
The. mechanism. by. which. nano-TiO 2 . improves. the. growth. of. spinach. seeds. still. needs.
further.study. 19
Another. report. explored. the. effects. of. nano-TiO 2 . on. willow. trees,. testing. the. possible.
toxicity.of.TiO 2 .nanoparticles.using.the.so-called.willow.tree.transpiration.test..The.ind-
ings. suggested. that. willow. trees. were. not. sensitive. to. exposure. to. TiO 2 . nanoparticles..
Effects.were,.however,.observed.for.zinc.and.zinc.oxide.particles,.but.these.effects.were.
determined.to.be.due.to.heavy.metal.toxicity.and.were.not.nano-size.speciic. 20

26.3.2 Nanoparticle Iron

A. phytotoxicity. study. was. carried. out. with. Cucurbita maxima . (pumpkin).. The. authors.
showed. that. plants. grown. in. an. aqueous. medium. containing. magnetite. nanoparticles.
(nano-Fe 3 O 4 ).can.absorb,.translocate,.and.accumulate.nanoparticles.in.the.plant.tissues..No.
particular.toxic.effects.were.observed,.but.the.effective.transport.of.the.nanoparticle.iron.
led.investigators.to.extend.their.studies.(see.Section.26.4).and.use.magnetite.nanoparticles.
as.a.potential.vehicle.to.deliver.compounds.to.plants. 21