Effect of fertilization rates on metabolites of duckweed (Wolffia globosa) as potential pharmaceutical resource

Due to the presence of numerous beneficial metabolites, wolffia (Wolffia globosa) has been utilized as possible medicinal resource. Therefore, the aim of this study was to determine how fertilization rates affected W. globosa metabolites including DPPH free radical scavenging activity, flavonoids, carotenoids, and ascorbic acid. The metabolites in W. globosa were examined in a 12-day growth trial with a reference fertilization rate (RF) of 173.6 mg/liter N, 40.3 mg/liter P, 100 mg/liter K, and 0.6 g/liter mineral mixture, along with five other different RFs [RF/2, RF/4, RF/8, RF/16, RF/20, and Control (no fertilizers)] NPK fertilization rates. The various treatments showed a significant variation in the metabolites of W. globosa (P <0.05). The outcome revealed that in the later stages of the experiment, RF/8 showed the greatest value of DPPH free radical scavenging activity (88.50±1.15%). The control group W. globosa had higher flavonoid concentrations (7.76±0.03 mg quercetin equivalent (QE)/g dry weight). Similarly, higher total carotenoid content (1117.09±0.77 μg/g dry matter in RF/8) as well as ascorbic acid (vitamin C) contents (141.41±11.66 mg/100 g dry matter in RF/4) were observed in the later on of the trial, representing opposite correlations with fertilization. The results revealed that it is suggested to avoid using an excessive amount of fertilizer during their growing in order to obtain the highest quantities of these metabolites and minimize adverse impacts on the quality of W. globosa.