Agriculture Reference
In-Depth Information
metals concentration and shoot biomass, plants cultivated on dual medium accumulated
approximately the same amounts of metals in the shoots as compared to plants submitted
completely to metals.
S. portulacastrum
M. crystallinum
0.1
0.12
R
2
= 0.7989
B/B
R
2
= 0.7752
Cd/Cd
0.08
0.1
Ni/Ni
0.08
0.06
B/Ni
B/Cd
0.06
0.04
0.04
0.02
0.02
0
1
2
3
4
2
4
6
0
8
10
12
K, mmol/plant
K, mmol/plant
0.1
0.12
R
2
= 0.7116
R
2
= 0.6493
0.1
0.08
0.08
0.06
0.06
0.04
0.04
0.02
0.02
0,2
0,4
0,5
1
0
0,6
0,8
1,5
0
Ca, mmol/plant
Ca, mmol/plant
0.12
0.1
R
2
= 0.8541
R
2
= 0.5471
0.1
0.08
0.08
0.06
0.06
0.04
0.04
0.02
0.02
10
15
0
5
20
25
10
0
20
30
40
Fe, µmol/plant
Fe, µmol/plant
Figure 7. Relationship between RGR (d-1) and K+ (mmol/ plant), Ca2+ (mmol/ plant) and Fe (µmol/
plant) shoot amounts. Means of 8 replicates.
Hence, the reduced Cd
2+
and Ni
2+
concentrations in the shoots of B/Cd and B/Ni plants
resulted principally from the dilution by growth. Nevertheless, since these data were related
to a short duration-experiment, we suppose that under a long term experiment, the quantity of
metal deposit in the shoots of these plants will be more important, because plants grown on
dual medium maintained their vigor without any symptoms of toxicity and are capable to
continue their life cycles. Thus, nutritional disturbances induced by heavy metals could limit
plant extraction capacities through its effects on plant growth. Some available data support
this assumption. For instance, it has been reported in some studies that high availability of K
+
,
Ca
2+
, Fe
2+
and Mg
2+
improved growth of plants subjected to Pb
2+
and Cd
2+
although the
presence of these cations in shoot-tissues (Cohen
et al.
1998; Kim
et al.
2002; Suzuki, 2005).
