Environmental Engineering Reference
In-Depth Information
Fig. 4.1
IC
25
, IC
50
and IC
75
values and their 95 % confidence intervals (CI) (mg/L) for
Sinapis
alba
L. after 72 h application; mean of three determinations with a standard deviations
3
Results and Discussion
3.1
Determination of Phytotoxicity
The first part of the study was carried out to determine the adverse effects of chro-
mium and nickel on
S. alba
seedlings. The deleterious effect was expressed as root
and shoot growth inhibition using regression analysis which yielded IC
25
, IC
50
and
IC
75
values (Fig.
4.1
). On the basis of these values, and their statistical evalua-
tion, metals can be arranged in the following rank orders of inhibition: for roots:
Cr(VI) ≥ Ni(II) > > Cr(III); for shoots: Ni(II) > Cr(VI) > > Cr(III). Both root and shoot
prolongation was most inhibited by Cr(VI) and Ni(II). All metals tested reduced
more root than shoot growth.
The presence of Cr and Ni in the external environment leads to changes in the
growth and development pattern of plants, and both these metals are reported to be
very toxic for root and shoot growth (Fargašová
1994
,
1998
). Ni in the presence of
0.1 µM NiCl
2
inhibited root and shoot elongation of canola and tomato seedlings,
and the roots appeared more sensitive than the shoots (Burd et al.
1998
). Prasad
et al. (
2001
) reported that the root length in
Salix viminalis
was affected more by Cr
than by Cd and Pb; and Fargašová (
1994
) stated that the adverse effect of Cr on
S.
alba
root growth was equal to that of Hg, and stronger than that of Cd and Pb, while
Ni reduced root length less than that by Cr (Fargašová
1998
). In accordance with
