Salicylic acid alleviates the toxicity effect of cadmium on germination, seedling growth, and amylase activity of rice

Cadmium (Cd) is a toxic heavy-metal pollutant in the environment. Salicylic acid (SA) is an essential component of plant resistance to pathogens and also plays an important role in mediating plant responses to some abiotic stresses. In the present investigation, the potential effects of SA in alleviating Cd toxicity during seedling stage of rice were studied. Seeds of rice (Oryza sativa L. cv. Xiushui 11) were sterilized and divided into two groups. Half of the seeds were pre-soaked in 0.1 mM SA solution for 24 h, then both groups were allowed to germinate under various Cd concentrations for 7 d. Cadmium treatments caused a gradual decrease in vigor index, root length, a-amylase activity, and the mitotic index of root tips. However, pretreatment with SA partially alleviated the negative effect of Cd on germination parameters and increased enzyme activity and mitotic index. Cadmium uptake by seedlings increased with increasing Cd concentration and followed Michaelis-Menten kinetics. Salicylic acid pretreatment of seeds influenced the Cd level in the seedlings by decreasing V-max. The results suggest that SA plays a positive role in rice-seed germination and early seedling growth by protecting it against Cd toxicity.