Bionematicidal efficacy of Chrysanthemum coronarium L. against Meloidogyne incognita

Root-knot nematodes (Meloidogyne incognita) are major plant pathogens and the environmental hazards associated with synthetic nematicides necessitate the development of eco-friendly alternatives. This study assessed the genotype-dependent bionematicidal potential of Chrysanthemum coronarium L. (Pusa 15-16 White, Cream and Yellow) using aqueous extracts of fresh and lyophilised leaves and flowers under in vitro conditions and correlated nematicidal activity with metabolite profiling through ultra-performance liquid chromatography-time-of-flight mass spectrometry (UPLC-TOF-MS). Second-stage juveniles (J₂) obtained from a pure culture maintained on tomato cv. Pusa Ruby were exposed to graded extract concentrations (20–100 %) and observations on mortality, immobilisation and revival were recorded at different exposure periods. The results revealed a significant increase in nematode mortality with increasing concentration and time of exposure. Among the genotypes, Pusa 15-16 White exhibited the highest efficacy, with fresh leaf extract causing 100 % mortality at ≥80 % concentration within 24 hr and at 60 % after 96 hr, while the overall maximum mean mortality (66.32 %) was recorded at 96 hr. Lower concentrations showed nematostatic effects as evidenced by revival test, whereas marigold root extract predominantly induced reversible immobilisation. UPLC-TOF-MS analysis detected pyrethrins, cinerins, jasmolins and flavonoids such as luteolin, quercetin and myricetin, which are likely responsible for observed nematicidal activity. This study provides the first evidence of flower colour-based genotypic variation in C. coronarium linked to its bioactive metabolite composition and highlights Pusa 15-16 White as a promising source of eco-friendly nematicidal compounds for sustainable nematode management.