The effect of inundation levels on secondary metabolites accumulation in Avicennia marina (Forsk.) roots under different salinity regimes

Salinity and inundation are factors that affect secondary metabolites. This research aims to study the range of typical secondary metabolite content in Avicennia marina growing at different salinity levels, analyze the level of inundation that causes peak stress, and examine the impact of inundation stress on A. marina under different salinity regimes. This study used a 2-factor factorial complete randomized design, namely salinity level (15, 20, 25, 30, and 35 ppt), and inundation level (10, 15, and 20 cm). The parameters measured were tannin content, total alkaloids, and total phenols in A. marina roots analyzed by spectrophotometry method. Data were analyzed by ANOVA and further tested with DMRT test. The concentration range of tannins, total alkaloids, and total phenols was 14.29–18.45%, 0.893–1.331 mgQE/g, and 62.7–8.75 mgGAE/g, respectively. Peak stress-induced by inundation in A. marina indicated by high secondary metabolite contents was differentiated based on the salinity regime. Peak secondary metabolite content was obtained from the combination of salinity and inundation of 25 ppt + 20 cm, 20 ppt + 15 cm, and 15 ppt + 10 cm for tannin, total alkaloid, and total phenol content with values of 18.26±0.17%; 1.301±0.021 mgQE/g; and 83.98±2.02 mgGAE/g. The research found that simultaneous effect of salinity and inundation impacted for all metabolites. Our result suggests that salinity has underlying effect on total alkaloid and total phenol concentration in A. marina roots, but not tannin. Inundation significantly affects tannin content, amplifying its effects on total alkaloid and total phenol content.