Silicon Alleviates Arsenic Toxicity in Maize Seedlings by Regulating Physiological and Antioxidant Defense Mechanisms

Arsenic (As) is a toxic heavy metal, found abundant in the environment, especially in industrial waste and pesticide formulations. The present study was conducted to evaluate the role of silicon (Si) application and its mechanism in the alleviation of toxic effects of As in maize (Zea mays L.) seedlings. The treatments consisted of four levels of As (0, 4, 8, and 12 mg kg(-1) of soil) factorially combined with three levels of Si (0, 50, and 100 mg kg(-1)) applied in the earthen pots placed in a triplicate completely randomized design. Results have shown a significant correlation of morphological and biochemical traits, which depicts that accumulation of Si-enhanced antioxidant defense mechanism which alleviates the As toxicity. Application of Si improved plant growth and gas exchange attributes by reducing the accumulation of As in plant tissues and reactive oxygen species production and by improving the membrane stability (lower malondialdehyde), synthesis of chlorophyll pigments, antioxidant enzymatic activities (superoxide dismutase, peroxidase, catalase), and proline accumulation. Application of Si at 100 mg kg(-1) of soil may be proved best for sustainable maize production under As toxicity. This will not only improve plant growth and development but also have positive impact on the environment.