ALLELOPATHIC ACTIVITIES OF SPATHIPHYLLUM WALLISII ROOT EXTRACT ON BLOOM-FORMING CYANOBACTERIUM "MICROCYSTIS AERUGINOSA"

Harmful algae blooms (HABs) contribute to economic loss as well as the threat to human and animal health. Among various technologies developed, allelopathic algicides are considered a promising technology to control excessive algal growth. In this study, the effect on Microcystis aeruginosa with different concentrations of Spathiphyllum wallisii root extract (SWRE) was tested. Results suggested that the SWRE doses from 0.5 to 4.0 g L-1 suppressed the growth of algae in a concentration-dependent manner. After 18 days of treatment, the highest inhibition rate was up to 99.2% and the chlorophyll-a (Chl-a) concentration in M aeruginosa was 2.7 mu g L(-1 )only. Inhibition of photosynthetic activity was reflected by changing photosynthesis efficiency (alpha) and relative electron transport rate (rETRs) of M aeruginosa cells. Results also showed the activity of antioxidant enzyme Peroxidase in M aeruginosa cells was inhibited by allelochemicals from SWRE. This resulted to the reaction between highly reactive and toxic intracellular free radicals reacting with the macromolecules in the algae.