Mitigating the Effect of Cadmium Toxicity on Growth and Lipid Composition of Sunflower by Foliar Application of Salicylic Acid

Abstract

Industrial emissions and human activities are the primary cause of heavy metals pollution in agricultural soils. An experiment was conducted for the investigation of healing effects of SA in sunflower growth and fatty acid composition on Cd exposure. This experiment was conducted according to factorial design. Sunflower plants were subjected to five different concentrations of Cd and subsequently treated with three treatments of salicylic acid via foliar spraying. Seven days after the application of final treatments of SA, plants of sunflower were collected and their roots, leaves and stem were separated, and growth parameters were measured. A Soxhlet system was used for the extraction of leaf oil, and fatty acid composition was analyzed by using gas chromatography. Statistical analyses revealed that growth parameters (length of roots and stems, number of leaves, and leaves fresh weight) were reduced when Cd concentration was increased, while application of SA enhanced these parameters as compared to controlled plants. The most prominent reduction in these parameters occurred at 0 μmol of SA and 200 μmol Cd. Cd exposure led to alterations in fatty acid composition, which resulted in an increase in saturated fatty acids and a reduction in the content of unsaturated fatty acids in sunflower leaves, whereas these effects were ameliorated on the foliar application of SA. Specifically, SA notably decreased the percentage of palmitic acid and increase linoleic acid. These findings suggest that by preserving membrane integrity through lipid esters, SA could serve as a potential growth regulator offering enhanced plant resistance to Cd stress and protection against oxidative stress induced by Cd.