Abstract

Aluminum stress is considered as a restricting factor for plant products. Therefore, many compounds have been applied to minimize the harmful effects of stress. Recently, the mitigating role of Silicon (Si) in Aluminum (Al) stress has received some attention. Si is known to increase tolerance in higher plants. Si in plants provides structural support and improves tolerance to diseases, drought and metal toxicity. We investigated the role of Si in alleviating Aluminum tolerance in Borago officinalis. Plants were grown in hydroponic culture and housegreen condition. When the seventh leaf appeared, plants were treated with five levels of Si: 0, 0.5, 1, 1.5 and 2 mM Si, after which they were treated with four levels of Al³⁺: 0, 20, 40 and 60 mM Al³⁺. Thereafter, the interaction effects of Silicon and Al stress on some physiological and biochemical parameters of Borago plants were investigated. Our results indicated that Al³⁺ significantly increased malondialdehyde (MDA), other aldehydes, proline content and proteins. Al³⁺ also caused a decrease in phenolic compounds. Silicon offset the negative impacts and increased tolerance of Borago to Al stress by enhancing phenolic compounds and proline contents compared to the control. Based on our observations that pretreatment with Si caused a decrease in peroxidation of lipids.

Key words: Borago, Silicon, Aluminum, malondialdehyde (MDA), proline, phenoli compounds, protein.