Effect of exogenously applied salicylic acid on cadmium chloride-induced oxidative stress and nitrogen metabolism in tomato (Lycopersicon esculentum L.)

Salicylic acid (SA) has a key role in the formation of induced systemic resistance and hypersensitive cells, but it has also been indicated to be effective in the formation of strong responses against abiotic stresses such as drought, cold, heavy metal toxicity, and osmotic stress. This study has demonstrated a connection between the total soluble protein and the nitrate reductase (NR) activity. In 20 μM CdCl2, 40 μM CdCl2 + 0.5 mM SA, and 100 μM CdCl2 + 0.5 mM SA treatments, on the 1st day following the treatment an increase was detected in the NR activity when compared to the control group (P 0.05); however, there was a decrease in the NR activity on the 3rd and 5th days of the treatment. An increase in protein amount was detected on the 1st day following the treatment whereas the amount of total soluble protein decreased on the 5th day in comparison to the control group. All concentrations of CdCl2 + 0.5 mM SA treatments caused an increase in the amounts of malondialdehyde, H2O2, and NO3 - on the 5th day of the treatment.