Efficacy of Potassium Silicate in Suppressing Meloidogyne enterolobii on Okra (Abelmoschus esculentus L.)

Abstract

Potassium silicate (PSi) is widely recognized as a biostimulant that enhances plant growth by improving nutrient uptake, promoting root development, and stimulating vegetative growth. In addition, it has been reported to exhibit nematicidal activity against root-knot nematodes (RKN). However, information regarding its application for the control of Meloidogyne enterolobii in Thailand remains limited. Therefore, the objective of this study was to evaluate the potential of PSi in suppressing M. enterolobii under both controlled laboratory and greenhouse conditions. Second-stage juveniles (J2s) and eggs of the nematode were exposed to PSi at concentrations of 250, 500, 1,000, and 2,000 ppm, and nematode mortality and hatching were assessed after 2 and 7 days of incubation, respectively. The highest J2 mortality was observed at 2,000 ppm (56.0 ± 5.8%), showing an effect comparable to KCl (positive control). Inhibition of nematode hatching was most pronounced at 500 - 2,000 ppm, resulting in reductions of 58.4 ± 3.7% to 64.5 ± 2.8% relative to the distilled water control. Moreover, PSi concentrations above 500 ppm exhibited nematicidal activity by directly attracting J2 movement. Under greenhouse conditions, okra plants treated with 1,000 and 2,000 ppm prior to nematode inoculation showed the greatest suppression of M. enterolobii, reducing galls, egg masses, and eggs by 42.1% - 74.4%, 62.8% - 78.9%, and 54.2% - 80.6%, respectively, and lowering the nematode reproduction factor (Rf) by 3- to 4-fold compared with the RKN-inoculated control. Plant growth, particularly plant height, was also markedly enhanced. Overall, PSi application as a soil drench not only promotes plant development but also exhibits strong potential for suppressing
M. enterolobii on okra, highlighting its value as a promising component of Integrated Pest Management (IPM) strategies for sustainable RKN control.

HIGHLIGHTS

• This study was conducted to evaluate the effectiveness of potassium silicate (PSi) in controlling Meloidogyne enterolobii parasitizing okra plants under both laboratory and greenhouse conditions.
• In laboratory assays, 2,000 ppm PSi exhibited the strongest nematicidal effect on juvenile mortality, while nematode hatching was most strongly suppressed at 500 ppm. Additionally, PSi concentrations above 500 ppm attracted nematode movement.
• Greenhouse experiments consistently confirmed the nematicidal effects against enterolobii, reducing the number of galls, egg masses, and eggs, as well as Rf values, while promoting plant growth.
• PSi demonstrates considerable potential against enterolobii and could be incorporated into IPM programs to reduce the damage caused by this nematode.

GRAPHICAL ABSTRACT