Asian Journal of Research in Biosciences

Medicinal values of plant based nematicides are more often attributed to the phytochemicals they contain. In vitro and screen house experiments were conducted to investigate the bio-nematicidal efficacy of alkaloids of J. curcas plant parts on the root-knot nematode, Meloidogyne incognita on okra (Abelmoschus esculentus). Efficacy of alkaloids was evaluated against nematode juveniles (J2s) after 24, 48 and 72 hours of incubation at 0, 5 and 10 ml in in vitro conditions. Although, nematode mortality was highest (99.3 %) after 72 h incubation period at 10 ml rate of application, there was no statistical difference with mortality ( 98.9 %) obtained at 5 ml. Under screen house conditions Alkaloids at 0,1,2,3,4 and 5 ml were applied to potted okra plants inoculated with 1,200 infective (J2) larvae of M. incognita. These were later laid out in a 3x6 factorial experiments arranged in Completely Randomized Design with five replications. Results showed that alkaloids applied at 5 ml /pot significantly (P=0.05) reduced root-galls and increased plant growth parameters on application of root and seed alkaloids than the untreated control in 2019 and 2020 years of study respectively. Root and seed alkaloids also increased Okra pod weight by 71 % (4.02 g) and 67 % (4.26 g) in both years. Leaf alkaloids gave least performance in growth and yield of Okra. These findings elucidated the potential of J. curcas alkaloids as possible good alternative for the control of root-knot nematode on okra. There is however, need for further studies in identifying new classes of bio-pesticides from natural plants to replace the synthetic chemicals used at present.