DefinePK

Abstract

ABSTRACT Plant defense response is a function of bioactive phytochemicals which confer pesticidal value or ability. The bio-nematicidal activity of Physicnut (Jatropha curcas) flavonoids on okra root-knot nematode was investigated in an in vitro and screenhouse study. Root flavonoids applied at 10ml/petri dish resulted in the highest nematode mortality (93 %) after a 72-hour incubation period and differed significantly (P<0.05) from nematode mortality (80 %) at 5 ml/pot. Although all potted plants in the screenhouse were inoculated with 1,200 second-stage nematode juveniles (J2s), results showed that, when compared to the untreated control that was severely galled (4.0), the application of leaf flavonoids resulted in a significant reduction (p<0.05) in number of galls and root-gall index on okra. The root-gall index decreased from 4.0 (severely galled) to 1.4 (rarely galled), while the seed and root flavonoids reduced galling to 2.0 (slightly galled). While improving growth and yield attributes, the highest dosage of 5 ml/pot had the greatest influence on the root-gall index and yield. There was a significant correlation (-) between yield and the root-gall index, supporting the idea that flavonoids might boost okra growth and production while reducing galling. While the application of root and seed flavonoids at a rate of 5 ml/pot resulted in the greatest 100 dry seed weight and enhanced mucilaginous properties of okra, increases in leaf areas, plant heights and okra pod weights (75% over control) were supported by the administration of root and seed flavonoids. These results demonstrated the possibility of Physicnut flavonoids as a viable alternative to synthetic nematicides for the management of M. incognita.