Unravelling the Morphological, Physiological, and Phytochemical Responses in Centella asiatica L. Urban to Incremental Salinity Stress

Abstract

Centella asiatica L. as a traditional medicinal plant is popular in several Asian countries and characterized by the presence of phytochemicals, such as phenolics and flavonoids. Soil salinity can affect the growth and phytochemical composition in this plant species. In this study, the effects of incremental soil salinity (0, 25, 50, 75, and 100 mM NaCl) on growth, physiological characteristics, total phenolic and total flavonoid contents, including the antioxidant activity of Centella asiatica L., were evaluated under greenhouse conditions. Salinity stress reduced growth, biomass production, and total chlorophyll contents, while increasing electrolyte leakage, Na⁺ and Cl^- contents in the shoots and roots. With the increase of salt concentration, total phenolic, total flavonoid content and antioxidant activities were increased. The results showed that centella can tolerate saline conditions up to 100 mM NaCl. Na⁺ exclusion from the roots, and that increases of phytochemical content in the shoots were related to the salt tolerance of this species.

Keywords: Na+ content; antioxidant activity; centella; phenolics; total flavonoid.

Figure 1

Total chlorophyll content of Centella asiatica L. as affected by different salinity levels. The experiment was carried out in triplicate. Different letters represent significant differences at the p < 0.05 (FW: fresh weight).

Figure 2

Electrolyte leakage of Centella asiatica L. as affected by different salinity levels. The experiment was carried out in triplicate. Different letters represent significant differences at the p < 0.05.

Figure 3

Hydrogen peroxide of Centella asiatica L. as affected by different salinity levels. The experiment was carried out in triplicate. Different letters represent significant differences at the p < 0.05.

Figure 4

(a) Shoot and (b) root Na⁺ content of Centella asiatica L. as affected by different salinity levels. The experiment was carried out in triplicate. Different letters represent significant differences at the p < 0.05.

Figure 5

(a) Shoot and (b) root Cl⁻ content of Centella asiatica L. as affected by different salinity levels. The experiment was carried out in triplicate. Different letters represent significant differences at the p < 0.05.

Figure 6

(a) Total phenolic, (b) total flavonoid (b) of Centella asiatica L. as affected by different salinity levels. The experiment was carried out in triplicate. Different letters represent significant differences at the p < 0.05. (GAE: gallic acid; QE: quercetin; DW: dry weight).

Figure 7

Antioxidant activity of Centella asiatica L. as affected by different salinity levels. The experiment was carried out in triplicate. Different letters represent significant differences at the p < 0.05.