Document Type : Complete scientific research article
Authors
1
Asociate Prof. in Soil Sci. Dept., Gorgan University of Agricultural Sciences and Natural Resources
2
Gorgan University of Agricultural Sciences and Natural Resources.
3
Soil Sci. Dept., Faculty of Water and Soil, Gorgan University of Agricultural Sciences and Natural Resources, Basij Sq., Gorgan, Iran.
Abstract
Background and Objectives: Soil pollution with heavy metals because of its damaging effects on the environment, including human health threat, toxicity in plants and long-term effects on soil fertility have become a global concern. Lead is the most common heavy metals in polluted areas that enter to ecosystems, plants and the food chain from various sources. As a non-essential element for plants, lead inhibits not only photosynthesis, changes enzyme activities, hormonal status and respiration but also plant growth, metabolism and mineral nutrient balance. It has been demonstrated that heavy metals, like lead, can significantly influence the uptake and translocation of some nutrients in plants. Thus, the imbalance of nutrients might be a symptom of heavy metal toxicity in plants. Thereby, interactions between lead and mineral nutrients may provide a specific insight into the role of mineral nutrients in lead accumulation and translocation in plants. Iron is the micronutrient most often found to be deficient in plants. Among the nutrients showing interactions with heavy metals, Fe is one of the most frequently concerned in many respects. Heavy metals influence Fe availability and adsorption in the root apoplasm, uptake into root cells, transport to the shoot and utilization in leaves. In turn, Fe deficiency may also modify heavy metal uptake and accumulation. The objective of this study was to investigate the interactive effect of iron and lead on cress (Lepidium sativum L.) growth.
Materials and Methods: For this, a factorial pot experiment in a completely randomized design with three iron levels (0, 20 and 40 mg kg-1) and three lead levels (0, 500 and 1000 mg kg-1) was carried out in triplicate. Lead and iron treatments were applied from lead nitrate and iron sequestrene-138 sources, respectively.
Results: The results showed that shoot fresh and dry weights, SPAD value, Fe content and uptake and lead translocation index of cress decreased with the increase of lead content in the soil (p≤0.01), but the lead content and uptake increased (p≤0.01). The increase of soil iron content significantly increased the shoot dry weights (p≤0.01), SPAD value and iron content and uptake (p≤0.05) and caused a significant decrease in the lead content, uptake (p≤0.01) and translocation index (p≤0.05). Interactive effect of iron and lead indicated that iron application along with lead significantly increased the shoot dry weight of cress (p≤ 0.05) and significantly decreased the lead content and uptake of cress (p≤ 0.05).
Conclusion: Iron plays an important role in reducing the adverse effects of lead in the cress. Hence, Applying 40 mg kg-1 of Fe as iron sequestrene-138 to reduce the adverse effects of lead on the cress recommended.
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