Protective Role of Zinc and Silicon in Mitigating Oxidative Stress in Swiss Chard (Beta vulgaris var. cicla) Grown under Lead-Contaminated Conditions

• Nagham Saddon Ibrahim¹ Fyaa Raad Yahya² Ahmed Yassin Hassan³

  Author

This study aimed to assess the effect of foliar application of chelated zinc and silicon (potassium silicate) on physiological traits of Swiss chard  grown under Pb-contaminated conditions. A pot experiment was conducted using a Randomized Complete Block Design (RCBD). The experiment included two lead concentrations (0 and 150 mg kg⁻¹ soil), three concentrations of chelated zinc (0, 0.1, and 0.3 g L⁻¹), and three concentrations of silicon (0, 1, and 3 g L⁻¹), resulting in 18 treatment combinations. Each treatment was replicated three times, giving a total of 54 experimental units. The results revealed that lead contamination significantly reduced leaf chlorophyll, nitrogen, potassium, and phosphorus contents, while significantly increasing leaf proline and lead concentrations. Foliar application of chelated zinc significantly improved chlorophyll content and the studied nutrient elements, while reducing the accumulation of proline and lead in the leaves. Likewise, silicon application enhanced the investigated physiological and nutritional characteristics by increasing leaf chlorophyll, nitrogen, potassium, and phosphorus contents and reducing proline and lead accumulation. Furthermore, significant effects were observed for both the two-way and three-way interactions among the experimental factors for most of the studied traits. The combined treatment of 150 mg kg⁻¹ lead + 0.3 g L⁻¹ chelated zinc + 3 g L⁻¹ silicon produced the highest mean values of leaf chlorophyll, nitrogen, potassium, and phosphorus contents, while recording the lowest values of leaf proline and lead contents. Based on the obtained results, it can be concluded that the foliar application of zinc and silicon represents an effective strategy for mitigating the toxic effect of lead contamination and enhancing the physiological performance and nutritional status of Swiss chard plants under environmental stress conditions.

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