Valorization of turmeric leaf waste for the management of banana burrowing nematode (Radopholus similis)

Abstract

Turmeric (Curcuma longa L.) foliage, typically discarded before rhizome harvest, was evaluated as a soil amendment for managing the banana burrowing nematode Radopholus similis. Ground turmeric leaf powder (GTLP) was assessed through in vitro toxicity assays, GC–MS profiling with molecular docking, pure-compound validation, glasshouse evaluation, and field trials. GTLP caused significant dose and time-dependent nematode mortality. GC–MS identified labda-8(17),12-diene-15,16-dial, curcumenol, 2-carene, isopulegol, and eucalyptol as major constituents. Docking suggested strong to moderate binding of key compounds to FAR-1, suggesting their possible involvement in parasitism-related processes and cuticle-associated functions. Pure-compound assays confirmed the high lethality of labda-8(17),12-diene-15,16-dial and isopulegol. In glasshouse and field studies, GTLP at 50 g plant⁻¹ (three applications) reduced nematode populations by 53–56%, enhanced beneficial nematode communities, improved plant growth, and increased yield by 24%, with a cost–benefit ratio of 1:2.3–2.4. These results demonstrate turmeric leaf waste as a sustainable and cost-effective strategy for managing R. similis in banana.