Evaluation of Preplant Seed Protectants for the Management of Root-Knot Nematode of Okra in Ghana

Abstract

Root-knot nematode (Meloidogyne incognita) poses a significant threat to okra production, resulting in substantial yield losses. The objectives of this study were to assess the impact of biological seed protectants on the growth and establishment of okra plants and nematode population reduction in soil. Okra seeds were coated with 40% sesame oil, 50% neem oil, 100% citrus oil, velum at 3.8 ml/7l of water, and a control (sterilized distilled water) at different time intervals of 30 min, 60 min, 90 min, and 120 min to determine the germination percentages and vigor. The experimental setup was laid out in a completely randomized design (CRD), with three replications, utilizing a Jacobson table for the germination test. The laboratory results demonstrated significant differences ($P<0.05$) in germination percentage and vigor index across the different time intervals. Neem oil, citrus oil, and velum exhibited higher germination percentages and vigor indices at all time intervals. Notably, 30-minute time interval proved to be efficient with 100% citrus oil producing 80.33% germination and 965 vigor index and 50% neem oil producing 75% germination and 994 vigor index. Field evaluations revealed citrus at 100% concentrations as seed coating (T5) and neem at 50% concentrations as seed coating (T3), with the highest nematode reductions (90.1% and 90.4%) and least reproductive factors (RFs) of 0.05 and 0.04, respectively, at the Atomic farms. The study has revealed that treating okra seeds with 100% citrus oil and 50% neem oil has the efficacy of reducing nematode reproduction in soil, while enhancing germination and seedling vigor, together with an improvement in growth and yield. Sesame oil has a negative influence on seed germination and vigor and is therefore not recommended as a preplant protectant.