Changes in phenolic profile, soluble sugar, proline, and antioxidant enzyme activities of Polygonum equisetiforme in response to salinity

This study intended to focus on the effect of different levels of NaCl (0–400 mM, at regular intervals every 100 mM) on the growth, secondary metabolites, and antioxidant enzyme activities of Polygonum equisetiforme, a wild plant with medicinal and industrial uses, which often grows in harsh environmental conditions. Our results showed that biomass production significantly decreased with salinity, while the leaf relative water content declined only at high levels of NaCl concentration (300–400 mM). In contrast, these higher doses of salt resulted in a significant increase in malondialdehyde (MDA) content. Both proline and soluble sugar (e.g., fructose, glucose, and sucrose) contents were enhanced under saline conditions. The methanolic extracts of the shoots included 10 flavonoids and 9 phenolic acids.