Modulation of cytotoxic effects of wastewater on barely seedlings by Aloe vera extract

Aim: This study was conducted to assess the mitigation effect of A. vera leaf ethanolic and water extracts on plant growth, MDA and protein content, and mitotic index of barley seedlings irrigated with sewage water. Methodology: The experiment was conducted in a green house in Al-Ahsa, Saudi Arabia, in plastic bags containing air-dried loam soil and compost (1:1). Wastewater samples were collected from Al-Ahsa Sewage Treatment Plant/Al-Ahsa/Saudi Arabia. Seeds of barley were exposed to the following treatments for three weeks: 100% treated wastewater, treated wastewater mixed with: 0.05 g ml(-1) A. vera alcoholic extract (Alc Ext) or 0.05 g ml(-1) A. vera water extract (Wat Ext), 0.15 g Alc Ext or 0.15 g ml(-1) Wat Ext. Similar test doses were prepared for untreated wastewater. A separate set of seeds was prepared using distilled water as a control. Germination rate, fresh and dry weight, protein content, MDA content and mitotic index were determined. Results: Untreated wastewater caused significant reduction in fresh weight while both treated and untreated wastewater showed insignificant decrease in dry weight of barley. No significant change in MDA contents were observed in all treatments, except for addition of 0.15 A. vera water extract to untreated wastewater. Protein content showed an increase in both treated wastewater (insignificant) and untreated wastewater (significant). Addition of A. vera extracts increased accumulation of protein in both shoot and root. A. vera alcoholic extract promoted significant increase in both root and shoot protein of treated wastewater, but only shoot protein of untreated wastewater. A significant reduction in mitotic index was induced by wastewater, while addition of A. vera extracts stimulated significant increase in mitotic index. Interpretation: A. vera possess reactive oxygen species scavenging ability and enzyme conservation activity in addition to stimulatory effects on cell proliferation and cell-cycle process that add a modulation credit on protein content and mitotic index of barley.