Pathogenicity of <i>Meloidogyne incognita</i> in selected groundnut varieties and its management with aqueous leaf extracts of wild sage (<i>Lantana camara</i> L.) and locust bean (<i>Parkia biglobosa</i> Jacq.)

Abstract

Meloidogyne incognita, on four groundnut (Arachis hypogaea L.) varieties. The efficacy aqueous leaf extracts of Lantana camara and Parkia biglobosa in the management of M. incognita infecting the groundnut varieties was also investigated. A preliminary study was first carried out from November 2014 – January 2015 in a screen house to access the pathogenicity of M. incognita on the four varieties of groundnut. Results obtained from soil and root nematode population led to field trials which involved the management of M. incognita using botanicals. The field experiment which was a 4x3 factorial fitted into Randomized Complete Block Design (RCBD) commenced in August, 2015. The effects of treatment on plants’ height, number of leaves, weight of fruits and on the population of root and soil nematodes were determined. Phytochemical screening of the active components in the test plant extracts was also conducted. Data collected were subjected to analysis of variance (ANOVA) and significant means were separated using Fisher’s protected LSD. Results from the study revealed that the growth parameters, yields and nematode population were significantly higher (p < 0.05) for the treatment combinations of L. camara and P. biglobosa than the control L. camara leaves extract at 100% performed better than P. biglobosa with respect to all the data measured. Phytochemical analysis revealed the presence of alkaloids, saponin, tannin, flavonoids, phenol and glycosides as the active chemical components in the test plants. This bio–active components were responsible for the nematotoxic effect of the leaf extracts. However results indicate that both aqueous extracts of L. camara and P. biglobosa can be used to manage the root-knot nematodes and increase the yield of groundnut without any toxic effects on the plants.

Keywords: Lantana camara, Parkia biglobosa, Meloidogyne incognita, Aqueous leaf extract and Pathogenicity