Environmental Engineering Reference
In-Depth Information
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Fig. 5.1
Influence of heavy metal stress on root anatomy of some selected plant species
2012
). High concentrations of heavy metals in root rhizosphere can considerably
alter root anatomical parameters (Seregin and Kozhevnikova
2008
), the most im-
portant among them are the dermal tissues, i.e., endodermis and exodermis (Lux et
al
.
2011
).
Several studies have showed that the heavy metal stress had an adverse effect on
root anatomical structures, (e.g. Kovačević et al
.
1999
; Shalini et al
.
1999
; Khudsar
et al
.
2001
; Papadakis et al
.
2004
; Kasim
2006
). Qaisar et al. (
2005
) reported some
specific anatomical modifications like reduced epidermis cell size, development of
large air spaces, and consequently, a reduced vascular region area, and as a result
significant reduction in the root diameter.
Llamas et al. (
2008
) reported the symptoms of heavy metal toxicity in rice
(
Oryza sativa
) and reported no change in root anatomical characteristics when the
roots were exposed to heavy metals for a short-term, however, a long-term exposure
resulted in a significant affected root structure, which affected membrane perme-
ability.
Heavy metals are more commonly accumulated in the parenchymatous tissues,
epidermis and phloem in root and stem, but less frequently these can accumulate in
other tissues also (Fig.
5.1
). Rabier et al. (
2008
) reported a significant accumulation
of Ni in epidermis and phloem of basal stem and roots in Australian native
Grevil-
lea exul
. Nickel stress also causes reduction in the number of xylem vessels, and
consequently, the function of the vascular tissues (Kovačević et al.
1999
).
