Effects of green synthesis of sulfur nanoparticles from Cinnamomum zeylanicum barks on physiological and biochemical factors of Lettuce (Lactuca sativa).

In this study, the effect of green synthesized sulfur nanoparticle (SNP) at different concentration (0, 0.01, 0.1, 1 and 10 mg/ml) on some physiological, phytochemical and biochemical traits of lettuce plants was investigated. For the first time, SNP were green synthesized using Cinnamomum zeylanicum barks extract. Our results indicated that the treatment of lettuce plants with 1 mg/ml of SNP improved the growth and photosynthetic parameters of lettuce plants than related control. Some other physiological parameters such as proline, glycine betaine and soluble sugars levels along with some phytochemical parameters like anthocyanin, total phenol, flavonoids and tannin contents were enhanced after treatment of the plants with same concentration of SNP. On the other hand, specific activity of antioxidant enzymes (catalase, ascorbate peroxidase and polyphenol oxidase) and stress markers level, MDA and H₂O₂ were reduced in the same treated lettuce plants. However, a concentration of 10 mg/ml of SNP exhibited toxicity on lettuce plants with inducing oxidative stress markers (H₂O₂ and MDA) and consequently reducing plant growth and biomass. This oxidative stress tend to diminish some physiological, phytochemical and biochemical parameters in treated lettuce plants. Overall, it can be concluded that the green synthesis SNP at an optimal concentration of 1 mg/ml improved physiological parameters in the lettuce plants making them potent to tolerate stressful conditions. However, higher concentration of SNP (10 mg/ml) indicated toxic effects on all of the physiological parameters.