Agriculture Reference
In-Depth Information
stress (Owen et al., 2008) whereas natural organic matter in soil or pore
water can sorb, coat or stabilize nano-particle suspensions and affect their
mobility, bioavailability, reactivity and toxicity (Mahendra et al., 2008;
Olszyk et al., 2008). This illustrates the daunting challenge of quantifying
and predicting the nano-particle properties and bioavailable concentration
to which plant roots may be exposed in nature.
Limited studies have been conducted to examine the phytotoxicity of
ENMs in plants. Carbon nano-tubes were observed to be adsorbed onto
the root surface of several crop species, but no visible uptake of CNTs
was shown However, Lin et al. (2009) observed the uptake, translocation
and transmission of carbon nano-materials in rice (Oryza sativa L.) plants.
Copper nanoparticles were found in root cell of mung bean (
Phaseolus ra-
distus
) and wheat (
Triticum aestivum
) in the forms of individual nanopar-
ticles and aggregates, and the bioaccumulation increased with increasing
nanoparticles dose (Lin and Xing, 2008) also observed the adsorption of
ZnO nanoparticles onto ryegrass (
Lolium Perenne
) root surface and con-
firmed the presence of the nanoparticles in the endodermis and xylem
cells, indicating that the nanoparticles were taken up by the plant. But
it seems that few (if any) ZnO nanoparticles were detected to transport
from root to shoot in that study. However, a species of pumpkin was found
to absorb, translocate, and accumulate of magnetite (Fe
3
O
4
) nanoparticles
from a hydroponic solution throughout the plant tissues (root, stem, and
leaves). (Owen et al., 2008) the plant uptake of magnetite nanoparticles
significantly depended on plant variety and environmental condition. (Zhu
et al., 2008) showed that lima bean (
Phaseolus limensis
) plants could not
absorb magnetite nano-particles from the hydroponic solution, and the up-
take and accumulation of the nano-particles were significantly reduced
in the pumpkin (
Curcubita maxima
) plants grown in sand compared with
those grown in the hydroponic solution and were not detected in the pump-
kin plants grown in soil probably due to the sorption of nano-particles by
soil and/or particle aggregation.
Clearly, interactions between plants and ENMs, such as uptake poten-
tial of different plant varieties, the effect of plant growth media condition,
mechanisms of uptake and translocation, and the interactions between the
particles and plant tissues at the cellular and molecular level, require fur-
ther in depth investigation. Such studies will help us understand the plant
uptake of ENMs as a potential transport and exposure route and its role
in bioaccumulation through the food chain. There are many unknowns re-
