The amount of silver in the soil and plants of the mining site
The amount of total and exchangeable silver element (mg− 1 kg dry weight) of the collected soils is shown in Table 1. According to the results, the total amount of silver in this region is 0.3 to 6.5 mg− 1 kg dry weight. Also, as shown in Table 1, the exchangeable amount of silver in the pavilion soil is less than 0.1 to 0.5 mg− 1 kg dry weight. The mean pH of soil samples ranged from 6.8 to 8.8 (Table 1). The amount of silver in harmel is in the range of 0.1 to 0.6 mg− 1 kg in the roots and 0.2 to 0.3 mg− 1 kg in the shoots and TF 0.5 to 2.0 (Table 2).
Table 1
Characteristics of soil samples collected (average and minimum-maximum) from silver metal contaminated mineral area
Site
|
number of
samples
|
Soil pH
|
Soil EC
|
Total silver
|
Exchangeable silver
|
|
|
|
(ms cm− 1)
|
(mg kg− 1)
|
(mg kg− 1)
|
1
|
10
|
7.5 ± 0.5
7.1–8.3
|
2.3 ± 1.1
1.1–3.4
|
1.3 ± 1.1
0.3–2.9
|
< 0.1
|
2
|
10
|
7.0 ± 0.1
7.0-7.1
|
8.2 ± 0.1
8.1–8.3
|
1.6 ± 0.5
0.3–1.7
|
< 0.1
|
3
|
5
|
6.8 ± 0.3
6.8–7.1
|
8.6 ± 0.4
8.2-9.0
|
3.4 ± 1.1
1.6–4.3
|
0.3 ± 0.1
0.2–0.4
|
4
|
5
|
7.1 ± 0.3
6.9–7.5
|
8.7 ± 0.5
8.2–9.2
|
1.4 ± 0.3
0.3–1.5
|
0.1 ± 0.1
< 0.3
|
5
|
6
|
7.7 ± 0.1
7.7–7.8
|
3.9 ± 0.1
3.8-4.0
|
4.5 ± 2.4
0.6–6.3
|
0.3 ± 0.1
< 0.5
|
6
|
10
|
8.8 ± 0.2
8.6–8.8
|
1.1 ± 0.1
1.1–1.2
|
5.8 ± 1.6
1.0-6.5
|
0.4 ± 0.2
0.1–0.5
|
Mean and range of silver concentrations (mg kg− 1dry weight) in soils, plants (shoots and roots) and TF collected from silver metal contaminated mineral area |
Table 2
Mean and range of silver concentrations (mg kg−1dry weight) in soils, plants (shoots and roots) and TF collected from silver metal contaminated mineral area
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)
Plant Growth
According to Fig. 1, there is a significant difference in shoot dry weight between different concentrations of Ag in each population. So that the lowest value at a concentration of 10 mgL− 1 Ag in both metallicolous populations and non-metallicolous is 67.2 and 66.8% dry weight loss compared to the control, respectively. Also, there is no significant difference between the two populations. Also, the results of the analysis of variance showed that the interaction between population and Ag treatment showed a significant effect on shoot dry weight (P < 0.05). Also, under doses of 5 and 10 mgL− 1 Ag, dry root weight in both harmel populations showed a significant decrease compared to the control. There is no significant difference between the two populations in different concentrations. Also, the results of the analysis of variance showed that the interaction between population and Ag treatment did not have a significant effect on root dry weight (Fig. 1a,b).
Figure 1 (c,d), shows that Ag treatment significantly reduced the length of the shoot and root compared to the control in both populations. In terms of shoot length, there was a significant difference in the levels of 5% in different concentrations in each population, so that at 10 mgL− 1 concentration in both populations, the lowest shoot length was observed compared to control. Also, the results of ANOVA showed that interaction between population and treatment had no significant effect on root and shoot length.
Ag Accumulation
Based on Fig. 2, Ag treatment at all concentrations caused a significant increase in Ag concentration in shoots and roots compared to control plants in both populations. The results showed a significant difference between the two populations at concentrations of 1, 2.5, 5 and, 10 mgL− 1, so that the highest concentration of shoot and root Ag at a concentration of 10 mgL− 1 of in metallicolous populations than non-metallicolous was observed. Also, analysis of variance showed that the interaction effect of population and Ag treatment on shoot and root Ag concentration was significant (P < 0.01).
Analysis of variance showed that the interaction effect of population and silver treatment on TF in harmel plants. The translocation factor of harmel increased as silver concentration enhanced in the cultivation (Fig. 2). The maximum increase in translocation factor value was recorded under silver 10 mgL− 1; as compared to the control plants, the transfer factor is less than one.
Photosynthetic Pigments
Based on Fig. 3, there is a significant difference in a, b and, total chlorophyll content between different concentrations of Ag in each population. The lowest total chlorophyll was observed in concentrations of 2.5, 5 and, 10 mgL− 1 Ag in both populations. Also, there is no significant difference between the two populations in different concentrations. According to the results of the analysis of variance, the interaction between population and Ag treatment did not show a significant effect on chlorophyll content.
Based on Fig. 3d, Ag treatment at all concentrations significantly reduced carotenoid content in both populations of harmel compared to the control. There is no significant difference between the two populations. Also, the results of the analysis of variance showed that the interaction of population and Ag treatment had no significant effect on carotenoid content.
Anthocyanin And Soluble Sugars Concentrations
According to Fig. 4a, it is observed that under the values of 5 and 10 mg− 1L Ag, the amount of anthocyanin in both populations of harmel showed a significant increase compared to the control. There is no significant difference between the two populations. The results also showed that the interaction between population and Ag treatment had no significant effect on number anthocyanins.
According to Fig. 4b, it is clear that Ag treatment at all concentrations caused a significant reduction in soluble sugars in both populations of harmel compared to the control. The results showed a significant difference between the two populations at concentrations of 1, 2.5, 5 and, 10 mg− 1L, so that the lowest amount of soluble sugars in the treatment of 10 mg− 1L non-metallicolous population is observed, which reduces 62% compared to the control. Analysis of variance showed that the interaction between population and Ag treatment on the concentration of soluble sugars was significant (P < 0.05).
Ascorbate (Asc), Dehydroascorbate (Dha) And, Glutathione (Gsh) Concentrations
Based on Fig. 5a, in different concentrations of Ag treatment, ASC content showed a significant increase compared to the control in both populations. The lowest amount of ASC in control plants and the highest ASC in Ag treatment of 5 mgL− 1 in metallicolous and non-metallicolous populations were observed with 306.9 and 351.3% increase compared to the control, respectively. The results of the analysis of variance showed that the interaction between population and Ag treatment had a significant effect on ASC content (P < 0.01).
Based on Fig. 5b, at different concentrations of Ag treatment, the content of DHA content showed a significant increase compared to the control in both populations. The results showed a significant difference between the two populations, so that the highest amount of DHA was observed in the treatment of Ag 10 mgL− 1 of the metallicolous population, which increased by 188% compared to the control. Also, the analysis of variance showed that the interaction between population and Ag treatment on the amount of DHA was significant (P < 0.05).
Reduced glutathione content is one of the most critical antioxidant indicators of plants in the face of stresses such as heavy metals. Based on Fig. 5c, the amount of GSH in different concentrations of Ag treatment showed a significant increase compared to the control in both populations. The highest GSH in Ag treatment of 10 mgL− 1 in both metallicolous populations and non-metallicolous increased by 40.7% and 46.1%, respectively, compared to the control. The analysis of variance showed that the interaction between population and Ag treatment had a significant effect on the amount of GSH (P < 0.01).
Antioxidant Enzyme Activities
Based on Fig. 6a, at different concentrations of Ag treatment, catalase (CAT) activity showed a significant increase compared to the control in both populations. The results showed a significant difference between the two populations at concentrations of 5 and 10 mgL− 1, so that the highest CAT activity was observed in the treatment of Ag 10 mg− 1L metallicolous population, which was an increase of 595.7% compared to the control plant. Also, the analysis of variance showed that the interaction of population and Ag treatment on CAT activity was significant (P < 0.01).
It is observed that under the values of 2.5, 5 and, 10 mg− 1L Ag, the activity of guaiacol peroxidase (GPX) in both populations of harmel showed a significant increase compared to the control (Fig. 6b). Also, no significant difference was observed between the two populations and, the analysis of variance showed that the interaction between the population and Ag treatment did not show a significant effect on GPX activity (P > 0.05).
According to Fig. 6c; it is observed that under different concentrations of Ag, ascorbate peroxidase (APX) activity in both populations of harmel showed a significant increase compared to the control. The lowest APX activity was observed in the control plant and the highest APX activity was observed in 5 and 10 mgL− 1 Ag treatment in both populations. Also, no significant difference was observed between the two populations and, the analysis of the variance table showed that the interaction between the population and Ag treatment did not show a significant effect on APX activity (P > 0.05).
Also, concentrations of 5 and 10 mgL− 1 Ag caused a significant increase in lipoxygenase (LOX) activity compared to the control in both populations (Fig. 6d). The highest LOX activity was observed in the treatment of 10 mgL− 1 Ag in both populations. Also, there is no significant difference between the two populations. The results of the analysis of variance showed that population interaction was not significant in Ag treatment (P > 0.05).
Superoxide dismutase (SOD) activity showed a significant difference between the two populations at concentrations of 1, 2.5, 5 and, 10 mgL− 1 (Fig. 6e). The highest superoxide dismutase activity was observed in the treatment of Ag 10 mgL− 1 in the metallicolous population, which was almost 80.7% higher than the control plant. Also, the analysis of variance showed that the interaction effect of population and Ag treatment on superoxide dismutase activity was significant (P < 0.01).