Changes of Polyphenols Contents, PPO and PAL Activities of Fresh Tobacco Leaves under NaCl Stress

A pot experiment with flue-cured tobacco NC89 planted in sand and three treatments (0, 350, 700 mmol/L NaCl with 1/3 Hoagland nutrient solution) was carried out to study the effect of NaCl stress on polyphenols of tobacco leaves and changes of polyphenols contents. The results showed that the flavonoid content increased significantly after 2 days of NaCl stress and the chlorogenic acid content began to increase after 6 days of NaCl stress. The rutin content increased significantly after 8 days of NaCl stress. The anthocyanin content first increased and then decreased. In different stress concentrations, the contents of chlorogenic acid, flavonoid, rutin, and anthocyanin were the highest in 350 mmol/L NaCl solution. PAL activity gradually increased, and had high significantly positive correlation with chlorogenic acid content and had positive correlation with rutin content at 350 mmol/L NaCl solution stress. PPO activity gradually increased and had correlation with chlorogenic acid. In general, the content of polyphenols increased and was closely related to change of PAL activity under the moderate NaCl stress treatment.