Volume 15, Issue 1 (3-2024)                   2024, 15(1): 51-69 | Back to browse issues page


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Department of Biology, Faculty of Science, Yasouj University, Yasouj, Iran.
Abstract:   (459 Views)
Abstract
Environmental stress in plants, particularly due to heavy metal presence, poses a significant challenge to their growth. Manganese, an essential micronutrient, can become detrimental when accumulated in soil and plants. To assess the impact of silicon on linseed (Linum usitatissimum L.) under manganese stress, a factorial experiment was conducted. Linseed plants were grown in hydroponic culture with four different manganese levels (2, 250, 500 and 1000 μM) along with five silicon treatment levels (0, 0.5, 1, 1.5 and 2 mM). Results revealed that increasing manganese stress levels led to a rise in proline, soluble sugars content, and manganese in the root and shoot, accompanied by a decrease in other studied traits. Notably, the application of 2 mM silicon consistently yielded the highest values across all manganese levels for the examined traits. Silicon application enhanced proline and soluble sugars content in leaves, consequently increasing plant photosynthetic capacity and leading to greater root and shoot dry weights under various silicon levels. The use of silicon significantly ameliorated the harmful effects of manganese in linseed under manganese stress conditions. Therefore, 2 mM silicon is recommended as a beneficial solution in areas contaminated with manganese, which can lead to the reduction of this heavy metal in the root and shoot of plants.

Background and Objective: Oilseeds, crucial for protein and energy, serve diverse purposes from food to industrial applications (Pramanik‎ et al., 2023). Linseed (Linum usitatissimum L.), an annual herb, faces heavy metal toxicity affecting plant growth. Environmental pollution, including the accumulation of heavy metals and the pollution of agricultural soils, is one of the most important global issues, which, in addition to reducing the quantity and quality of agricultural products, endangers their sustainability. Manganese (Mn), essential for plants, can turn toxic in excess. Silicon (Si) has been recognized for its role in mitigating biotic and abiotic stress, including heavy metal stress (Shi et al., 205; Imtiaz et al., 2016) and has beneficial effects on growth and development of many plants. In the northeast and northwest of Iran, there are rich soils of manganese and active mines of this element. Moreover, in the vicinity of metal smelting and refining factories, manganese pollution has been reported, and a wide range of agricultural lands adjacent to them are under the influence of toxic concentrations of this element. This study aimed to externally apply silicon to linseed and observe the plant's response to manganese toxicity.

Methods: The experiment employed a factorial design with different Mn (as MnSO4) and Si (as Na2SiO3) levels in a soilless culture of linseed. Distilled water and quarter-strength Hoagland solution were used for irrigation. Mn and Si treatments were applied from the six-leaf stage for four weeks. Several physiological and biochemical traits were measured post-harvest. Statistical assays were carried out by ANOVA test and means were compared by the least significant difference (LSD) test using SAS 9.1 software.

Results: The results revealed that an increment in the Mn stress level increased proline, soluble sugars content, and manganese in the root and shoot, accompanied by a decrease in other studied traits. The interaction of Mn and Si stresses significantly influenced various traits in linseed. The Mn stress increased proline and soluble sugars content, while Si application enhanced this effect. The Si treatment significantly reduced the Mn concentration in the root and aerial parts of the plant. The application of 2 mM silicon consistently yielded the highest values of examined traits across all manganese levels. Silicon application enhanced proline and soluble sugars content in leaves, consequently increasing plant photosynthetic capacity and leading to greater root and shoot dry weights under various silicon levels. As a result, treatment with 2 mM Si demonstrated the most significant improvement in physiological and morphological traits. The use of silicon significantly ameliorated the harmful effects of manganese in linseed under manganese stress conditions.

Conclusions: The study highlights the positive impact of Si on plant characteristics under Mn stress. The 2 mM silicon is recommended as a beneficial solution in areas contaminated with manganese. The Si application proved beneficial in reducing Mn absorption and accumulation in aerial organs, offering an effective and economical solution for increased crop production in Mn-stressed environments.

References:
1. Imtiaz, M., Rizwan, M.S., Mushtaq, M.A., Ashraf, M., Shahzad, S.M., Yousaf, B., Saeed, D.A., Rizwan, M., Nawaz, M.A., Mahmood, S., Tu, S., 2016. Silicon occurrence, uptake transport and mechanism of heavy metals, minerals and salinity enhanced tolerance in plants with future prospects: A review. J. Environ. Manage. 183, 521529. https://doi.org/10.1016/j.jenvman.2016.09.009.
2. Pramanik, J., Kumar, A., Prajapati, B., 2023. A review on flaxseeds: Nutritional profile, health benefits, value added products, and toxicity. eFood 4(5), e114. https://doi.org/10.1002/efd2.114.
3. Shi, Q., Bao, Z., Zhu, Z., He, Y., Qian, Q., Yu, J., 2005. Silicon-mediated alleviation of Mn toxicity in Cucumis sativus in relation to activities of superoxide dismutase and ascorbate peroxidase. Photochemistry 66(13), 15511559. https://doi.org/10.1016/j.phytochem.2005.05.006.


 
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Type of Study: Research | Subject: Plant growth under stressful conditions
Received: 2023/11/7 | Accepted: 2024/02/11 | Published: 2024/06/18

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