Salicylic acid induces amelioration of chromium toxicity and affects antioxidant enzyme activity in Sorghum bicolor L.

Chromium (Cr(VI)) would inflict serious morphological, metabolic, and physiological anomalies in plants ranging from chlorosis of shoot to lipid peroxidation and protein degradation. Cr(VI) toxicity is often associated with oxidative stress, caused by the excessive formation of reactive oxygen species (ROS). In response, plants are equipped with a repertoire of mechanisms to counteract heavy metal (HM) toxicity. Salicylic acid (SA) plays a key role in the signal transduction pathways of various stress responses, demonstrating the protective effect of SA against abiotic stress factors. So, the present investigation was carried out to study the amelioration of pernicious effects of different concentration of Cr(VI) (0.0, 2.0, and 4.0 mg Cr(VI) kg^-1 soil in the form of potassium dichromate) by treatments of salicylic acid solution viz. pretreatment and foliar spray via antioxidative enzymes and their metabolites.

With different treatments of salicylic acid solution, the reinstatement from ill effects of Cr(VI) toxicity was contemplated but the most conspicuous effect was observed when salicylic acid solution was supplied through the foliar spray (0.50 mM). This was accompanied with an increase in ascorbate peroxidase activity and hydrogen peroxide content and decrease in peroxidase activity and ascorbic acid content.This study suggests that salicylic acid when applied through pre-treatment of seeds or through a foliar spray can be used to ameliorate the toxic effects of chromium (VI). Salicylic acid has the great potential for reducing the toxicity of heavy metals without negatively impacting the growth of the plants.