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ORIGINAL PAPER
Effect of heavy metal pollution on mineral absorption in sunflower(Helianthus annuus L.) hybrids
Unaiza Aslam • Iftikhar Ahmad • Mumtaz Hussain •
Ameer Khan • Abdul Ghani • Irfan Mustafa • Sabahat Jalal •
Muhammad Anjum Aqeel • Saira Asif • Haroon Ahmed
Received: 22 January 2013 / Revised: 28 August 2013 / Accepted: 9 September 2013 / Published online: 22 October 2013
� Franciszek Gorski Institute of Plant Physiology, Polish Academy of Sciences, Krakow 2013
Abstract The present study was conducted in a potted
experiment to examine the effects of chromium pollution
on absorption of mineral nutrients and some morpho-
physiological attributes of two sunflower (Helianthus an-
nuus L.) hybrids (FH-331 and FH-259) in the presence and
absence of ethylene diamine tetra acetic acid (EDTA) used
as a chelating agent. Four concentrations of chromium
(Cr3?) i.e., 0, 20, 30 and 40 mg kg-1 with and without
0.3 g kg-1, EDTA as chelating agent were applied to
25-day-old sunflower plants. A gradually decreasing trend
in absorption of all minerals and other parameters studied
were observed. Different treatments of Cr3? as well as
Cr3? and EDTA significantly reduced root and shoot fresh
weight; however, root, shoot and achene Cr3? contents of
two sunflowers hybrids under higher chromium and EDTA
stress varied significantly whereas movement of Cr3?
contents to leaves was non-significant. Absorption of Na?,
K?, N2 and P through roots and shoots significantly
reduced with increasing concentration of Cr3? treatments.
In fact addition of EDTA to the medium further enhanced
the toxicity of chromium.
Keywords Chromium contents � Mineral
absorption � Sunflower � Heavy metal pollution �Nitrogen � Phosphorus
Introduction
With growth and development of different kinds of
industries, and extensive use of chemical fertilizers and
pesticides, the contamination of soil with heavy metals has
become a serious environmental problem (Kuffner et al.
2008). Metals are an integral component of lithosphere and
contaminate atmosphere as well as biosphere through
industrial effluents and other human activities. In heavily
industrialized areas, numerous soil sites have become
contaminated with high concentrations of heavy metals
greatly affecting the agricultural produce (Nicholson et al.
2003).
The presence of higher concentrations of heavy metals
in the soil can reduce biological activity and fertility of soil
leading to yield reduction (McGrath et al. 1995).
When heavy metal ions reach higher levels in the
environment, through phyto-extraction they are transmitted
from plant roots to shoots where they disturb normal
metabolic processes (Foy et al. 1978).
Among heavy metals, chromium has become a very
common environmental pollutant. It is discharged by lea-
ther tanning, electroplating and alloy preparing industries
Communicated by M. Prasad.
U. Aslam � M. Hussain � S. Jalal
Department of Botany, University of Agriculture,
Faisalabad, Pakistan
I. Ahmad (&) � A. Khan � A. Ghani � I. Mustafa
Department of Biological Sciences, University of Sargodha,
Sargodha, Pakistan
e-mail: [email protected]
M. A. Aqeel
University Colleges of Agriculture, University of Sargodha,
Sargodha, Pakistan
S. Asif
Department of Botany, PMAS-Arid Agriculture University,
Murree Road, Shamsabad, Rawalpindi, Pakistan
H. Ahmed
Department of Biosciences, COMSATS Institute of Information
Technology, Park Road, Chak Shahzad, Islamabad, Pakistan
e-mail: [email protected]
123
Acta Physiol Plant (2014) 36:101–108
DOI 10.1007/s11738-013-1390-y
in their effluents (Ozdemir et al. 2005). The worldwide
annual Cr3? discharge has been estimated around 105.4
million tons (Han et al. 2004). Chromium toxicity greatly
influences seed germination and some physiological pro-
cesses in plants. The ability of a seed to germinate in a
medium containing Cr3? may indicate its level of tolerance
to this metal (Peralta et al. 2001). Plant growth and
development is severely affected by Cr3? compounds. It
proves toxic to some higher plants even at 100 lM kg-1
dry weight (1). However, some crops are not affected by
low Cr3? concentration i.e., 3.8 9 10-4 lM (Huffman and
Allaway 1973).
Chromium toxicity inhibits seed germination, degrades
pigment status, nutrient balance, antioxidant enzymes and
induces oxidative stress in plants (Panda et al. 2003). The
phytotoxicity of Cr3? has been studied in both lower and
higher plants. Cr3? is thought essential for animals in trace
amounts, but at higher doses it proves toxic and induces
oxidative stress in both plants and animals (Panda and
Choudhury 2005; Jomova and Valko 2011). It considerably
affects growth, water balance, pigment content and initiates
lipid per oxidation by causing oxidative damage to plants
(Panda and Patra 2000).
The present study was conducted to determine the
effects of chromium pollution on absorption of mineral
nutrients and some morpho-physiological attributes of
commonly grown sunflower (Helianthus annuus L.)
hybrids (H) namely FH-331 and FH-259 in the presence
and absence of ethylene diamine tetra acetic acid (EDTA)
as a chelating agent.
Materials and methods
Experiment
A pot experiment was conducted to assess the effect of
chromium chloride (CrCl3) and EDTA on two sunflower
(H. annuus L.) hybrids i.e., FH-331 (H1) and FH-259 (H2).
The experiment was carried out in the Old Botanical
Garden, University of Agriculture Faisalabad. Seeds of
both sunflower hybrids were available in the Botany
Department, University of Agriculture, Faisalabad. Ten
seeds were sown in 42 two plastic pots (20 cm diameter
and 24 cm depth) containing 8 kg dry sand. The growing
plants were irrigated at regular intervals of 1 week with full
strength Hoagland’s nutrient solution till the termination of
the experiment. After germination the plants were thinned
to maintain six seedlings in each pot. The treatments were
applied 25 days after germination. Following seven metal
(CrCl3) treatments (T) with and without EDTA were
applied:
T0: Control,
T1: 20 ppm CrCl3,
T2: 30 ppm CrCl3,
T3: 40 ppm CrCl3,
T4: 20 ppm CrCl3 ? 0.3 g l-1 of EDTA,
T5: 30 ppm CrCl3 ? 0.3 g l-1 of EDTA,
T6: 40 ppm CrCl3 ? 0.3 g l-1 of EDTA.
The experiment was laid out in a completely random-
ized design (CRD) with three replications. The plants were
uprooted carefully 1 week after treatment application and
washed with distilled water. The data for the following
parameters were recorded
Determination of ions
Plant shoot and root samples were analyzed for following
ions
Naþ; Kþ; PO3�4 ; N2 and Cr3þ:
Wet digestion
The plant material was dried at 75 �C for 72 h in an oven
prior to grinding. The dried and well-ground material
(0.1 g) was digested with sulfuric acid and hydrogen per
oxide following the method given by Wolf (1982). Adding
distilled water the volume of the extract was made 50 ml,
then filtered and used for the analysis.
K?, Na? determination
Potassium (K?) and sodium (Na?) were determined by
flame photometer. Graded series of standards (ranging
from 10 to 100 ppm) of K? and Na? were prepared and
standard curves were drawn. The values of K? from flame
photometer were compared for standard curves and total
quantities were computed.
Phosphorus (P)
Phosphorus was determined spectrophotometrically using
Barton’s reagent. Five ml of digested plant sample was
taken and Barton’s reagent was added to make up the
volume up to 50 ml by distilled water and measured with
the help of spectrophotometer (Jackson 1962).
Nitrogen estimation
Total nitrogen was estimated by Kjeldahl apparatus
(Bremner 1965). The reagents were prepared using 40 %
NaOH, 4 % boric acid solution and sulfuric acid standard
0.01 N. A mixed indicator of bromocresol green (0.03 %)
and 0.2 ml methyl red in 400 ml alcohol (90 %) was
102 Acta Physiol Plant (2014) 36:101–108
123
prepared and 25 ml mixed indicator in 1,000 ml of 4 %
boric acid solution was dissolved.
Procedure
Ten ml liquid sample was taken in Kjeldahl flask and
placed on the Kjeldahl ammonium distillation unit and then
10 ml of 40 % sodium hydroxide (NaOH) solution was
added and the flask was immediately connected to distil-
lation apparatus. Ten ml boric acid (4 %) was also taken
along with mixed indicator in 100 ml conical flask. When
the distillate remained approximately 40–50 ml, the coni-
cal flask was removed and distillation unit was turned off.
The distillate was cooled for a few minutes and titrated
against 0.01 N, H2SO4 up to end point having a light-pink
color of mixed indicator in 4 % boric acid solution. The N2
content was calculated using the formula:
N2 %ð Þ ¼ sample reading� blank readingð Þ � normality of acid� 0:0014
weight of sample 0:1 gð Þ� 100:
Determination of Cr3? content (mg g-1 dry wt.)
Cr3? ions were determined with atomic absorption spec-
trophotometer (Hitachi AAS-Z-8200 with polarized Zee-
man effect).
Yield components
Three plants per treatment in each replica of two hybrids
were randomly selected and following yield components
were calculated.
100 Achene weight (g)
The achenes from three plants of each treatment were
intermingled and 100-achenes were counted. The weight
was taken by means of an electrical balance.
Achene yield per plant
Total seed weight of three plants of each treatment was
taken and mean value per plant was calculated for eco-
nomic yield.
Statistical analysis
Data for all parameters were analyzed statistically by analysis
of variance technique based on two factors CRD using CO-
STAT computer package (Cohort Software Beckley Cali-
fornia). Hybrid and treatment means were compared by
applying Duncan’s multiple range test (Duncan 1975).
Results
Shoot fresh weight (g)
Analysis of variance of data for root fresh weight (g), shoot
fresh wt. (g), root chromium contents, shoot Cr3? contents,
shoot sodium, root sodium, shoot potassium and root
potassium of two sunflower hybrids treated with different
level of chromium and EDTA showed highly significant
differences for hybrid means, treatment means and for
treatment 9 hybrid interaction means (Table 1). The
maximum reduction (36.52 %) in shoot fresh weight was
recorded for T6 (40 ppm CrCl3 ? 0.3 g l-1 EDTA) as
compared with control for hybrid 2. It seems that appli-
cation of EDTA exacerbated the toxic effects of chromium
on shoot fresh weight (Fig. 1).
Root fresh weight (mg g-1 dry wt.)
T6 (40 ppm CrCl3 ? 0.3 g l-1 EDTA) caused 16.54 %
reduction in root fresh weight for hybrid 1 as observed in
T3 where only CrCl3 was applied. Treatments (T1–T6)
differed significantly from T0 (control) (Table 1). A com-
parison between hybrids showed more toxic effects of
chromium on root fresh weight of H1 (FH-331) (Table 2).
Cultivar and treatment means were compared by applying
Duncan’s multiple range test (Duncan 1975).
Shoot Cr3? contents (mg g-1 dry wt.)
The shoot Cr3? contents gradually increased with
increasing chromium concentration and its maximum value
was observed in T6. When EDTA was applied along with
chromium, it increased metal’s mobility and higher Cr3?
values were observed for hybrid 1 in T4 and hybrid 2 in T6.
The differences between hybrids for their response to
chromium and EDTA treatment were also significant.
Root Cr3? content (mg g-1 dry wt.)
A comparison among treatment means showed minimum
accumulation of Cr3? in T0 (control) while its maximum
accumulation was observed in T5 and in T6 which differed
significantly from T1, T2, T3 and T4. The joint application of
chromium and EDTA (T4–T6) increased Cr3? content in roots
as compared with that recorded in the singly chromium or
EDTA treatments (T2 and T3). The difference between
hybrids for the Cr3? content in their roots was also significant.
Leaf Cr3? content (mg g-1 dry wt.)
Statistical analysis of data showed non-significant differ-
ences between hybrid means, treatment means and for
Acta Physiol Plant (2014) 36:101–108 103
123
treatment 9 hybrid interaction means for their leaf Cr3?
contents. The accumulation of Cr3? in leaves showed a
gradual increase with the increasing concentrations of
applied CrCl3. However, the joint application of CrCl3 and
EDTA (T4–T6), improved Cr3? accumulation in leaves
indicating that EDTA might have mobilized it from the soil
toward other plant organs including leaves. However, both
hybrids possessed same level of Cr3? varying non
significantly and with increasing the concentration of applied
CrCl3, the leaf Cr3? content also increased in both hybrids.
Achene Cr3? content (mg g-1 dry wt.)
Data for achene Cr3? contents of two sunflower hybrids
treated with different levels of chromium and EDTA
showed non-significant differences between hybrids and
Table 1 Analysis of variance (ANOVA) of the data for shoot and root fresh wt. (g), and ionic (Cr3?, Na?, K?, P and N2) contents in the leaves,
shoot, root and achenes of two sunflower (Helianthus annuus L.) hybrids under chromium and EDTA stress
S.O.V. df SFW RFW Leaf Cr3?
contents
Shoot Cr3?
contents
Root Cr3?
contents
Achene Cr3?
contents
Shoot Na?
contents
Treatments 6 34.45*** 6.93*** 38.56 ns 0.09*** 0.12*** 0.02** 24.13*
Hybrids 1 363.73*** 51.74*** 89.99 ns 0.01*** 0.05*** 8.57 ns 91.52**
T 9 H 6 25.18*** 3.55*** 36.30 ns 0.01*** 0.01*** 4.35 ns 128.46***
Error 28 3.39 0.40 43.52 0.001 0.001 7.08 9.11
S.O.V. df Root Na?
contents
Shoot K?
contents
Root K?
contents
Shoot P
contents
Root P
contents
Shoot nitrogen
contents
Root nitrogen
contents
Treatments 6 93.21* 47.87*** 18.87 *** 0.02 ns 0.03*** 6.88*** 8.21***
Hybrids 1 116.66 ns 1152.38*** 1.16 ns 0.05 ns 4.46 ns 1.15 ns 4.33 ns
T 9 H 6 113.72** 55.56*** 10.88*** 0.04 ns 0.005*** 7.76*** 0.001*
Error 28 29.07 8.45 1.47 0.01 1.59 6.80 1.18
SFW shoot fresh weight, RFW root fresh weight, ns non-significant
*, **, *** Significant at 0.05, 0.01 and 0.001 levels, respectively
0
0.5
1
1.5
2
2.5
3
H1 H2 H1 H2 H1 H2 H1 HC2
Leaf Cr3+ contents Shoot Cr3+ contents Root Cr3+ contents Achene Cr3+ contents
T0 T1 T2 T3 T4 T5 T6
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
H1 H2 H1 H2 H1 H2 H1 C2
Shoot P contents Root P contents Shoot Nitrogen contents Root Nitrogen contents
T0 T1 T2 T3 T4 T5 T6
0
20
40
60
80
100
120
140
160
H1 H2 H1 H2
Shoot fresh weight Root fresh weight
T0 T1 T2 T3 T4 T5 T6
0
50
100
150
200
250
300
H1 H2 H1 H2 H1 H2 H1 H2
Shoot Na+ contents Root Na+ contents Shoot K+ contents Root K+ contents
T0 T1 T2 T3 T4 T5 T6
Fig. 1 Comparison of means for shoot and root fresh wt. (g), leaf, shoot, root and achene Cr3?, Na, K, P and N contents of two sunflower
(Helianthus annuus L.) hybrids under chromium and EDTA stress
104 Acta Physiol Plant (2014) 36:101–108
123
Ta
ble
2M
ean
sho
ot
and
roo
tfr
esh
wt.
(g),
and
ion
icco
nte
nts
(Cr3
?,
Na,
K,
Pan
dN
)in
the
leav
es,
sho
ot,
roo
tan
dac
hen
eso
ftw
osu
nfl
ow
er(H
elia
nth
us
an
nu
us
L.)
hy
bri
ds
un
der
chro
miu
m
and
ED
TA
stre
ss
Tre
atm
ents
Sh
oo
tfr
esh
wei
gh
tR
oo
tfr
esh
wei
gh
tL
eaf
Cr3
?co
nte
nts
Sh
oo
tC
r3?
con
ten
tsR
oo
tC
r3?
con
ten
tsA
chen
eC
r3?
con
ten
tsS
ho
ot
Na?
con
ten
ts
aH
1H
2H
1H
2H
1H
2H
1H
2H
1H
2H
1H
2H
1H
2
T0
20
.53
b2
5.6
1a
2.4
7b
c4
.48
a0
.03
a0
.02
a0
.02
h0
.05
h0
.05
k0
.03
6k
0.0
2a
0.0
2a
33
.33
a3
0.6
6ab
T1
18
.67
bc
23
.65
a1
.54
cd3
.01
b0
.07
a0
.13
a0
.15
g0
.15
g0
.14
j0
.28
hi
0.0
7a
0.0
7a
25
.23
i2
7.3
3b
c
T2
15
.62
cd2
0.5
7b
1.5
4cd
2.1
4b
c0
.08
a0
.17
a0
.25
f0
.24
f0
.25
i0
.40
cde
0.1
3a
0.1
3a
24
cde
24
.66
cd
T3
14
.57
de
19
.78
b1
.47
cd2
.31
bc
0.1
4a
0.2
3a
0.3
2cd
0.3
4ab
0.3
2g
h0
.43
bcd
0.1
7a
0.1
7a
23
.33
cde
23
.66
cde
T4
14
.17
de
19
.31
b1
.47
cd2
.11
bc
0.1
6a
0.1
9a
0.4
1a
0.2
6ef
0.4
7b
0.3
4f
g0
.14
a0
.14
a2
1.0
0d
ef2
1.8
3d
ef
T5
11
.5ef
19
.09
b0
.86
d1
.94
c0
.24
a0
.28
a0
.36
ab0
.29
def
0.3
6ef
g0
.45
bc
0.1
5a
0.1
5a
17
.00
fg1
9.5
ef
T6
10
.52
f1
8.7
8b
0.7
3d
1.6
2cd
0.2
6a
0.3
2a
0.3
1cd
e0
.34
ab0
.38
def
0.5
5a
0.1
7a
0.1
7a
11
.00
h1
4.1
6g
h
Hy
bri
dm
ean
15
.08
b2
0.1
7a
1.4
4b
2.5
6a
0.1
4b
0.1
9a
0.2
6a
0.2
3b
0.2
8b
0.3
5a
0.1
2a
0.1
2a
22
.14
b2
4.0
4a
Tre
atm
ents
Ro
ot
Na?
con
ten
tsS
ho
ot
K?
con
ten
tsR
oo
tK
?co
nte
nts
Sh
oo
tP
con
ten
tsR
oo
tP
con
ten
tsS
ho
ot
nit
rog
enco
nte
nts
Ro
ot
nit
rog
enco
nte
nts
H1
H2
H1
H2
H1
H2
H1
H2
H1
H2
H1
H2
H1
H2
T0
39
.00
ab4
1.0
0a
18
.66
b2
5.3
3a
11
.33
a1
1.6
6a
0.3
9a
0.2
9ab
0.2
6a
0.3
a0
.05
a0
.05
a0
.05
a0
.03
a
T1
37
.33
abc
35
.66
abc
13
.66
cd1
9.3
3b
9.6
6ab
8.3
3b
cd0
.35
a0
.14
bc
0.2
6a
0.2
6a
0.0
2a
0.0
2a
0.0
4a
0.0
4a
T2
35
.00
abc
35
.66
abc
13
.33
cd2
0.6
6ab
8.6
6b
c8
.00
bcd
0.1
7b
c0
.10
c0
.18
a0
.22
a0
.02
a0
.02
a0
.02
a0
.02
a
T3
34
.66
abcd
34
.33
abcd
12
.33
cd1
9.6
6b
8.6
6b
c7
.00
cde
0.1
7b
c0
.10
c0
.15
a0
.13
a0
.02
a0
.01
a0
.02
a0
.01
a
T4
33
.00
abcd
29
.00
cde
12
.33
cd1
9.0
0b
6.3
3d
e6
.33
de
0.1
2c
0.1
0c
0.1
1a
0.1
1a
0.0
2a
0.0
1a
0.0
1a
0.0
1a
T5
31
.00
bcd
e2
5.6
6d
e1
2.0
0d
19
.00
b5
.33
ef5
.66
ef0
.09
c0
.08
c0
.13
a0
.10
a0
.01
a0
.01
a0
.01
a0
.01
a
T6
29
.00
cde
22
.33
e1
1.6
6d
17
.00
bc
3.6
6f
4.0
0f
0.0
8c
0.0
6c
0.0
9a
0.1
0a
0.0
1a
0.0
1a
0.0
1a
0.0
5a
Hy
bri
dm
ean
34
.14
a3
1.9
4a
13
.42
a1
9.9
9b
12
.92
a1
9.7
1a
0.1
9a
0.1
2a
0.1
6a
0.1
7a
0.0
1a
0.0
1a
0.0
2a
0.0
2a
a–f
sho
win
gth
esi
gn
ifica
nce
dif
fere
nce
(p\
0.0
5)
aF
H-3
31
(H1)
and
FH
-25
9(H
2)
Acta Physiol Plant (2014) 36:101–108 105
123
for treatment 9 hybrid interaction means but highly sig-
nificant differences for treatment means. The maximum
achene Cr3? contents were examined in T5 and T6.
Shoot Na? content (mg g-1 dry wt.)
Analysis of variance of data for shoot Na? content of two
sunflower hybrids treated with different concentration of
chromium and EDTA showed highly significant differ-
ences for hybrid means treatment 9 hybrid interaction
means and for treatment means (Tables 1, 2). In T3 a
26.57 % decrease in shoot Na? content was observed. T1
(20 ppm CrCl3), T2 (30 ppm CrCl3) and T3 (40 ppm CrCl3)
differed non significantly from each other but differed
significantly from T0 (control). The maximum reduction
(55.73 %) in Na? content was observed in the shoots of T6
(40 ppm CrCl3 ? 0.3 g l-1 EDTA) treated plants. Chro-
mium toxicity decreased shoots Na? contents of both
hybrids which was more pronounced in H1 as compared to
H2. Maximum shoot Na? contents were recorded for T0
(control) which gradually decreased from T0 to T6
(Table 2).
Shoot K? content (mg g-1 dry wt.)
Statistical analysis of the data showed highly significant
differences for hybrid means, treatment means and for
treatment 9 hybrid interaction means. The shoot K? con-
tents decreased gradually from T0 (control) to T3 (40 ppm
CrCl3). In T3 it decreased by 27.28 %. Application of both
chromium and EDTA as T6 (40 ppm CrCl3 ? 0.3 g l-1
EDTA) caused maximum (34.83 %) reduction in shoot K?
contents and differed significantly from all other treat-
ments. A comparison of hybrids indicated that shoot K?
content was more severely affected by CrCl3 in H1 (FH-
331) than that recorded H2 (FH-259).
Shoot P contents (mg g-1 dry wt.)
Statistically non-significant differences for hybrid means,
treatment means and treatments 9 hybrid interaction
means were observed for P contents of shoots (Table 1)
however, a gradual decrease in P contents from T0 to T6
was found. As EDTA was added, it enhanced toxicity of Cr
and maximum decrease in shoot phosphorous contents was
observed in T6 (40 ppm CrCl3 ? 0.3 g l-1 EDTA) i.e.,
79.41 % compared with the control. However, the P con-
tent in the shoot of both hybrids did not vary significantly
in response to chromium and EDTA treatments.
Shoot N2 contents (mg g-1 dry wt.)
The N2 content in the shoot of sunflower plants treated with
different concentration of chromium and EDTA showed
non-significant differences for hybrids mean, highly sig-
nificant differences for treatments mean and as well as for
treatments x hybrids interaction means (Table 1). In T2
(30 ppm CrCl3), T3 (40 ppm CrCl3), T5 (30 ppm
CrCl3 ? 0.3 g l-1 EDTA), T6 (40 ppm CrCl3 ? 0.3 g l-1
EDTA), shoot nitrogen contents showed a gradual reduc-
tion. In T3–T6 up to 50 % reduction in shoot N2 was
observed. The maximum N2 content was recorded in the
shoot of control (T0) which decreased gradually with
increasing concentration of CrCl3 (Table 2).
Root Na? contents (mg g-1 dry wt.)
Statistical analysis of data showed non-significant differ-
ences for hybrid means, significant differences for treat-
ment means and highly significant differences for treatment
9 hybrid interaction means in respect of Na? contents
(Table 1). In T6 (40 ppm CrCl3 ? 0.3 g l-1 EDTA),
35.85 % reduction in root Na? content was observed while
T3 (40 ppm CrCl3) decreased it by 13.80 %. Moreover, T3
and T6 differed significantly with one another and from T0
(control) as well. A probe into T 9 H interaction indicated
that in FH-331 the Na? content in the roots of sunflower
hybrid decreased with increasing concentration of CrCl3(T0–T3) (Table 2).
Root K? contents (mg g-1 dry wt.)
Analysis of variance of data for K? content in the roots of
two sunflower hybrid treated with different concentration
of chromium and EDTA showed non-significant differ-
ences between hybrids, but highly significant differences
for treatments means as well as for treatments 9 hybrids
interaction means (Table 1). In T3 (40 ppm CrCl3) treated
sunflower plants K? content in roots decreased by 31 %. In
T1 (20 ppm CrCl3), T2 (30 ppm CrCl3), and T3 (40 ppm
CrCl3) treated sunflower plants as well as the K? content in
the roots was significantly reduced from control (T0).
However, in T6 (40 ppm CrCl3 ? 0.3 g l-1 EDTA) treated
sunflower plants 66.66 % reduction in root K? contents
was recorded. This effect was 34 % higher than T3
(40 ppm CrCl3) treated sunflower plants. A comparison
between hybrids showed that with increasing concentration
of CrCl3, the root K? contents gradually decreased
(Table 2).
106 Acta Physiol Plant (2014) 36:101–108
123
Root P contents (mg g-1 dry wt.)
The P contents in the roots of two sunflower hybrids treated
with different level of chromium and EDTA revealed
highly significant differences among treatment means, and
for treatment x hybrid interaction means, but non-signifi-
cant differences for hybrid means (Table 1). The maximum
reduction in the P contents of roots was observed in the T6
(40 ppm CrCl3 ? 0.3 g l-1 EDTA) treated sunflower
plants. A gradual decrease in root phosphorous contents
was observed from T0 to T6 in both hybrids whereas H2
(FH-259) seemed more sensitive than its counterpart sun-
flower hybrid (FH-331) (Table 2).
Root N2 contents (mg g-1 dry wt.)
Statistical analysis of the data for root N2 contents of two
sunflower hybrids treated with different level of chromium
and EDTA showed non-significant effects for hybrid means,
highly significant differences among treatment means and a
significant treatment 9 hybrid interaction (Table 1). A
reducing trend for root N2 contents was observed in T3
(40 ppm CrCl3), T4 (20 ppm CrCl3 ? 0.3 g l-1 EDTA), T5
(30 ppm CrCl3 ? 0.3 g l-1 EDTA) and T6 (40 ppm
CrCl3 ? 0.3 g l-1 EDTA) and all these treatments differed
significantly from T0 (control). A probe into the
hybrid 9 treatment interaction indicated that root N2 con-
tents of both hybrids decreased with increasing concentra-
tion of CrCl3 and maximum reduction was recorded in T6
(40 ppm CrCl3 ? 0.3 g l-1 EDTA).
Discussion
The contamination of soil by chromium severely affects a
number of metabolic processes in plants (Shanker et al.
2004). When taken up by plants it gets accumulated in
different plant organs and negatively affects photosynthe-
sis, respiration, water relations and interferes with the
absorption and distribution of plant essential mineral
nutrients ultimately leading to reduced plant growth and
yield (Rubio et al. 1994). During this study, the uptake and
accumulation of metals decreased the shoot and root
length, though dry matter accumulation was not affected
accordingly. Metal (Cr3?) treatments also decreased
absorption and accumulation of mineral like K?, Ca2?, and
Mg2? by different plant organs. It seems Cr3? interfered
not only with nutrient uptake, but also with their distribu-
tion into the different plant parts in accordance with pre-
vious reports (Rubio et al. 1994; Shanker et al. 2004).
Similarly the hindered uptake of nutrient elements (N2, P,
K?, Na?, Ca2?, and Mg2?) has been reported for tomatoes
treated with Cr3? (50 and 100 mg l-1) in Moral et al.
(1995), Athar and Ahmad (2002), Fozia et al. (2008).
These findings are in line with Sujatha and Gupta (1996)
who reported that tannery effluent irrigation caused
micronutrient deficiencies in several agricultural crops. It
was observed that Cr3? reduced the plant fresh and dry
matter (Shanker et al. 2004). The reduction in shoot bio-
mass with increasing concentration of Cr3? was attributed
to the sensitivity of enzymes of the photosynthetic carbon
reduction cycle (De Filippis and Ziegler 1993).
EDTA being a chelating agent binds with metals and
improves it leaching or absorption and uptake by plants and
their subsequent distribution to different plant organs,
hence increasing their toxicity. As such the exposure of
plants to Cr3? along with EDTA may further exacerbate its
toxicity, because of increased absorption of Cr3? by plants
resulting from destroyed physiological barriers of the root
(Luo et al. 2006).
The accumulation of Cr3? was recorded in the least
amount in the seed part (edible) than other plant parts,
which may be attributed to slow translocation of Cr3? from
roots to the aerial parts (Davies et al. 2001; Singh et al.
2004; Singh and Sinha 2005). However, plant treated with
Cr3? along with EDTA showed more Cr3? in their roots
and stems which may be attributed to the improved
mobility of metallic ions in the presence of a chelating
agent. As such the accumulation of Cr3? was examined in
maximum amount in the roots, its intermediate content in
stems and leaves, and the lowest in seeds.
The higher levels of Cr3? reduced leaf P content during
this study. Similar results have been already reported
during previous studies as well (Saraiva 2001; Shanker
et al. 2004) as examined. This reduction in P contents could
be attributed to Cr3? toxicity resulting into reduced root
growth, impaired penetration of roots into the growth
medium and subsequently lower translocation of P to aerial
parts (Dube et al. 2009).
Sunflower hybrids varied considerably in their Cr3?
content as well as nitrogen contents in different plant
organs which may be attributed to the variation between
the genetic makeup of both hybrids. Similar parietal dif-
ferences in the chromium and nutrient uptake have been
already determined for Hordeum vulgare (Perby and Jen-
sen 1983).
Author contribution Mumtaz Hussain designed the
research. Iftikhar Ahmad analyzed the data, and Ameer
Khan, Sabahat Jalal wrote the paper. Saira Asif and Haroon
Ahmed improved the manuscript. Unaiza Aslam, Abdul
Ghani, Irfan Mustafa, Muhammad Anjum Aqeel conducted
the research. All authors have read and approved the final
manuscript.
Acta Physiol Plant (2014) 36:101–108 107
123
Acknowledgments I am extremely thankful to my colleges at
University of Agriculture, Faisalabad for their cooperation during this
study.
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