Assessment of the antioxidant and nematicidal activities of an aqueous extract of Chromolaena odorata (L.) King and Robins against Radopholus similis infestation in Cavendish banana plants: An in vitro and in vivo study

Here, we investigated the antioxidant and nematicidal activities of the aqueous leaf and stem extract of Chromolaena odorata (L.) (AECO) against Radopholus similis, a nematode pest of banana plants. In vitro antioxidant analysis involved testing AECO at concentrations ranging from 50 to 300 µg/mL in 2,2-diphenylpicrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging assays. Both in vitro and in vivo experiments were performed using doses of 780, 1,560, 3,120, 6,250, and 12,500 mg DW/L AECO. We assessed the egg hatching inhibition and juvenile survival rate of R. similis, content of antioxidant compounds in banana roots, dry weight of the aerial parts and roots, and the nematode density in the soil. In vitro antioxidant assays revealed substantial DPPH-scavenging (59.67-92.13%) and ABTS radical inhibition (37.26% at 300 µg/mL) activities. In vitro experiments using 12,500 mg DW/L AECO exhibited significant inhibition (p < 0.05) of R. similis egg hatching (26.98%, 55.25%, and 82.92% at 24, 48, and 72 h, respectively) and reduced juvenile survival (p < 0.05). In vivo experiments demonstrated a significant decrease (p < 0.05) in malondialdehyde concentration and an increase (p < 0.05) in antioxidant pro-duction (glutathione, catalase, and superoxide dismutase) in banana roots after AECO treatment. Plant biomass showed significant differences (p < 0.05), with the highest values (15.38 ± 0.13 g the aerial part dry weight and 29.32 ± 0.15 g the root dry weight) recorded in the AECO12500 treatment. Notably, R. similis density was significantly decreased (p < 0.05) in the soil after AECO treatment, with maximum inhibition obtained using 12,500 mg/kg. These findings emphasize the potential of AECO for pest management and its relevance to the cultivation of Cavendish bananas.