IRON TOXICITY IN TRITICUM AESTIVUM L. SEEDLINGS: A CONCENTRATION- AND TIME-DEPENDENT ANALYSIS OF MORPHOPHYSIOLOGICAL, OXIDATIVE, AND ANTIOXIDANT RESPONSES
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Abstract
Iron (Fe) is an inevitable micronutrient essential for all living organisms; however, its excess can disrupt cellular metabolism and induce oxidative stress. This study investigated the concentration- and time-dependent effects of Fe toxicity on growth, oxidative damage, and antioxidant responses in Triticum aestivum L. (wheat) seedlings exposed to 0, 100, 200, and 500 μM Fe-EDTA for up to 14 days. Moderate Fe exposure (100 μM) promoted seedling growth, resulting in an 11.3% increase in shoot length and 18.4% increase in fresh biomass on the 12th day compared with the control. In contrast, 500 μM Fe significantly inhibited growth, causing a 23.6% reduction in root length by the 14th day. Excess Fe enhanced oxidative stress, as reflected by increased MDA (malondialdehyde) and H₂O₂ (hydrogen peroxide) accumulation. The highest MDA was recorded under 500 μM Fe, showing increases of 35.2% and 39.4% in shoot and root tissues, respectively, on the 14th day. Increased oxidative stress was accompanied by activation of antioxidant defenses, with catalase (CAT) activity increasing up to 3.67-fold and ascorbate peroxidase (APX) activity increasing by 61.5% under Fe stress. Overall, prolonged exposure to elevated Fe concentrations induced oxidative damage and growth inhibition in wheat seedlings, while enhanced antioxidant enzyme activities contributed to mitigating Fe-induced cellular injury. These findings improve our understanding of the temporal responses of wheat seedlings to excess Fe and the participation of antioxidant systems in mitigating stress-induced damage.
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