Resistance status of mint to meloidogyne enterolobii and utilization of mycorrhizal fungi as a control strategy.

Abstract

Mint (Mentha spicata) is an important aromatic and medicinal crop used raw or processed into oil for a variety of consumption purposes. Medicinal plants play a critical role in providing medications for humans, particularly in poor countries, where communities depend on such medicinal plants for traditional medicinal use. However, with global climate change, root-knot nematodes are often considered to be among the most devastating pests in agriculture, resulting in a major decline in productivity of such medicinal plants which are found to be susceptible to root knot nematodes. The objectives of the study were to determine host status and host sensitivity of Mentha spicata to Meloidogyne enterolobii and the evaluation of whether Arbuscular Mycorrhizal Fungi (AMF) will reduce M. enterolobii in the event the test plant is susceptible. A micro plot and shade net experiment was conducted in 2025. To assess the host status and sensitivity, M. spicata seedlings were inoculated with the following treatment levels; 0, 25, 50, 125, 250, 625, 1250 & 3125 eggs and J2s of M. enterolobii, with the treatments laid in a Randomized Complete Block Design (RCBD). At 56 days after initiating treatment, plant and nematode variables were measured. The nematode reproductive factors (Rf) were greater than one in all treatment levels under micro plot setting, while under the shade net it was above one at the lower treatment levels and below unity as the treatment levels increased. Results showed that plant parasitic nematodes negatively reduced number of branches, plant height, and chlorophyll content with relative impacts (RI) ranging from 13 to 42%, 12 to 69% and 30 to 93% in microplot setting. While for a shade net setting only plant height was reduced with a RI of 8 to 41%. The test plant was susceptible to root knot nematodes; therefore no assessment of resistant was necessary, AMF was utilized as potential bio-control strategy. Each mint seedling was inoculated with 3000 eggs+ J2s of M. enterolobii. At 56 days after nematodes inoculation, AMF treatment levels of 0, 10, 20, 30, 40g were initiated arranged in RCBD. The fungus employed was RRHIZ-UP, and the isolates identified in the product were Funneliformis coronatum, Funneliformis mosseae, Claroideoglomus etunicatum, and Rhizophagus irregularis species. All the Arbuscular Mycorrhizal Fungi (AMF) treatment levels reduced nematodes infestation. The results of the study indicated that AMF improved plant parameters such as plant height, stem diameter, chlorophyll content, and fresh shoot weight under micro plot settings with relative impact ranging from 22 to 79%, 19 to 88%, 83 to 219% and 25 to 69%. While under shade net settings stem diameter was improved by 12 to 43%. On nematode variables, AMF had significant effect, reducing plant parasitic nematodes with relative impact of 13 to 30% on root galls, 17 to 31% in J2 in roots, 20 to 31% for eggs in roots, 25 to 35% for J2 in soil, 31 to 46% for eggs in soil and 18 to 27% for the final population (Pf).While for shade net settings nematodes were reduced by 16 to 33% on root galls, 12 to 28% in J2 in roots, 12 to 25% for eggs in roots, 6 to 38% for J2 in soil, and 9 to 24% for the final population (Pf). In conclusion, mint was a host to M. enterolobii and AMF controlled nematode population densities. Arbuscular Mycorrhizal Fungi could be used as potential bio-control strategy to manage root knot nematodes infestation in plants.