Comparative Evaluation of Nematicidal and Phytotoxic Activities of Essential Oils From Different Parts of <i>Alpinia malaccensis</i>

Plant essential oils (EOs) are gaining importance as eco-friendly alternatives to synthetic pesticides. This study evaluated chemical composition, nematicidal, and phytotoxic potential of EOs extracted from distinct parts (rhizome, leaves, fruits, and flowers) of Alpinia malaccensis. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that monoterpenes dominated EOs, with key compounds α-terpinolene, camphene, and p-cymene. Nematicidal activity of EOs was evaluated against Meloidogyne incognita via mortality and egg hatchability bioassays. The fruit and flower EOs exhibited the highest nematicidal activity, with LC₅₀ and IC₅₀ values of 0.96 and 0.07 µL/mL at 96 h, respectively. In phytotoxicity bioassay against wild radish (Raphanus raphanistrum) and chicory (Cichorium intybus), all EOs exhibited concentration-dependent inhibitory effects. Against radish seeds, phytotoxic impact of EOs was moderate. However, it was higher against radish seeds, where flower EO showed seed germination inhibition ranging from 90% to 100% and seedling growth inhibition from 94.14% to 100% at 1.00 µL/mL concentration. Molecular docking studies of selected EO constituents with five nematode target proteins identified 1-naphthalenol and cis-calamenene as the most promising candidates, exhibiting strong binding affinities. These findings highlight potential of A. malaccensis EOs as natural nematicidal and phytotoxic agents, providing valuable insights for sustainable pest and weed management strategies.