1- University of Mohaghegh Ardabili. Ardabili, Iran
Abstract: (13 Views)
Introduction and Objectives: Given the contamination of medicinal plants with heavy metals and the high potential of these plants in absorbing and transferring them to usable parts, and therefore the side effects related to the presence of heavy metals in herbal medicines used in Iran, today researchers are looking for a solution that can reduce the toxic effects of heavy metals in the soil and improve the quality of crops grown in soils contaminated with heavy metals. The use of cost-effective and environmentally safe nanoparticles for remediation of metal-contaminated soils and biosorption of trace and potentially toxic elements via microalgae or algal extract has received much attention in the past and recently. Therefore, this experiment was conducted to feed fennel with biostimulants and investigate some physiological and reduce the absorption of heavy metal chromium and ultimately maintain the quantity and quality of fennel (Foeniculum vulgare).
Materials and methods: This study was conducted as a factorial in a randomized complete block design in 2023-2024 under greenhouse conditions with 3 replications. Treatments included chromium stress at two levels (0 (control) and 100 mg/kg soil) and foliar spray at three levels (control, algal extract at a concentration of 1 mg/L, and selenium nanoparticles at a concentration of 20 mg/L). At the four-leaf stage, foliar spraying was performed at three levels of zero, algal extract (1 mg/L), and selenium nanoparticles (20 mg/L) three times with an interval of 15 days. Ten days after the plant was exposed to the desired stress, sampling was performed from the control and treatment samples to examine the physiological parameters of the plant.
Results: Findings: The results of the analysis of variance of the mutual effect of foliar spraying × heavy metal stress in relation to the antioxidant enzymes catalase and superoxide dismutase were significant. The results of the mutual effect of selenium nanoparticles × green algae extract was significant for the traits of proline amino acid content and chlorophyll a, chlorophyll b and total chlorophyll, but there was no significant effect for antioxidant enzymes catalase and superoxide dismutase, electrolyte leakage and malondialdehyde. The results showed that the concentration of malondialdehyde, antioxidant enzymes catalase and superoxide dismutase, proline content and ion leakage percentage increased significantly under chromium stress, while the content of photosynthetic pigments decreased compared to the control. The application of biostimulants increased the activity of antioxidant enzymes catalase and superoxide dismutase, proline content and photosynthetic pigment concentration compared to the control, but the malondialdehyde content decreased compared to the control. In fennel, the activity of catalase and superoxide dismutase enzymes increased in the interaction of chromium with 1 mg/L algal extract, 20 mg/L selenium nanoparticles, and their interaction, respectively, compared to the control. The highest percentage of catalase and superoxide dismutase enzyme activity was related to chromium stress and the lowest concentration of these enzymes was related to the control. The highest activity of antioxidant enzymes under chromium stress after the control was assigned to foliar spraying with algal extract. The interaction effect of selenium nanoparticle and algal extract decreased the content of malondialdehyde and increased photosynthetic pigments. Also, by spraying 20 mg/L selenium nanoparticles, 1 mg/L algal extract and their interaction, the proline content increased compared to the control. As a result, the damage caused by chromium toxic metal stress was moderated by strengthening the antioxidant and photosynthetic system of fennel plant by selenium nanoparticles and algal extract.
Conclusion: In general, among the studied biological stimuli under chromium stress, foliar spraying with algal extract compared to selenium nanoparticle has strengthened the antioxidant system of fennel plant and in this way it has been able to inhibit the accumulation of free radicals and also maintain the integrity of the membrane under chromium stress by reducing the content of malondialdehyde.
Materials and methods: This study was conducted as a factorial in a randomized complete block design in 2023-2024 under greenhouse conditions with 3 replications. Treatments included chromium stress at two levels (0 (control) and 100 mg/kg soil) and foliar spray at three levels (control, algal extract at a concentration of 1 mg/L, and selenium nanoparticles at a concentration of 20 mg/L). At the four-leaf stage, foliar spraying was performed at three levels of zero, algal extract (1 mg/L), and selenium nanoparticles (20 mg/L) three times with an interval of 15 days. Ten days after the plant was exposed to the desired stress, sampling was performed from the control and treatment samples to examine the physiological parameters of the plant.
Results: Findings: The results of the analysis of variance of the mutual effect of foliar spraying × heavy metal stress in relation to the antioxidant enzymes catalase and superoxide dismutase were significant. The results of the mutual effect of selenium nanoparticles × green algae extract was significant for the traits of proline amino acid content and chlorophyll a, chlorophyll b and total chlorophyll, but there was no significant effect for antioxidant enzymes catalase and superoxide dismutase, electrolyte leakage and malondialdehyde. The results showed that the concentration of malondialdehyde, antioxidant enzymes catalase and superoxide dismutase, proline content and ion leakage percentage increased significantly under chromium stress, while the content of photosynthetic pigments decreased compared to the control. The application of biostimulants increased the activity of antioxidant enzymes catalase and superoxide dismutase, proline content and photosynthetic pigment concentration compared to the control, but the malondialdehyde content decreased compared to the control. In fennel, the activity of catalase and superoxide dismutase enzymes increased in the interaction of chromium with 1 mg/L algal extract, 20 mg/L selenium nanoparticles, and their interaction, respectively, compared to the control. The highest percentage of catalase and superoxide dismutase enzyme activity was related to chromium stress and the lowest concentration of these enzymes was related to the control. The highest activity of antioxidant enzymes under chromium stress after the control was assigned to foliar spraying with algal extract. The interaction effect of selenium nanoparticle and algal extract decreased the content of malondialdehyde and increased photosynthetic pigments. Also, by spraying 20 mg/L selenium nanoparticles, 1 mg/L algal extract and their interaction, the proline content increased compared to the control. As a result, the damage caused by chromium toxic metal stress was moderated by strengthening the antioxidant and photosynthetic system of fennel plant by selenium nanoparticles and algal extract.
Conclusion: In general, among the studied biological stimuli under chromium stress, foliar spraying with algal extract compared to selenium nanoparticle has strengthened the antioxidant system of fennel plant and in this way it has been able to inhibit the accumulation of free radicals and also maintain the integrity of the membrane under chromium stress by reducing the content of malondialdehyde.
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