The host status of selected soybean cultivars to Meloidogyne enterolobii under field and greenhouse conditions

Abstract

Soybean is a popular oilseed crop in South Africa with an increase in prodution and hectares that doubled in last 10 years. Crop production is predicted to increase with 41% by 2030. The crop is infected and damaged by a series of pests and diseases of which plant parasitic nematodes are among the most important pests. In South Africa, root-knot nematodes (RKN), Meloidogyne spp., are the most serious pests of soybean, and growers who have a RKN problem find it difficult to control the nematode and its damage. In the Mpumalanga region, soybean farmers suffer from serious yield losses due to infection of soybean by RKN. Among the different Meloidogyne spp., the more pathogenic Meloidogyne enterolobii, that is difficult to control, was previously found in maize and potato in the Mpumalanga region. The study's objectives are to identify the RKN species present at the field trial site using morphological and molecular techniques, to determine the host status of selected soybean genotypes commonly grown in the Highveld region of the Mpumalanga province to the RKN species occurring in a field site with a high natural infestation and verify the results in a glasshouse trial where inoculation with the RKN species took place. The soybean genotypes evaluated under field conditions, at intervals of 30, 56 and 100 days after planting confirmed the results of the glass house studies terminated at 56 days after RKN inoculation. Yield of the genotypes at the field plot was also analyzed to determine whether some genotypes were tolerant to M. enterolobii. Results showed that genotype P61T38R and P48T48R were able to suppress the reproduction of RKN under greenhouse conditions significantly compared to the susceptible control while in the field trials, genotype P48T48R had a significantly lower infestation compared to the susceptible control. Genotype P59T33R showed tolerance as it produced a good yield even under high M. enterolobii population densities in the field site. Informing farmers about soybean genotypes that are poor hosts or tolerant to M. enterolobii and that can be cultivated to reduce its population densities, can be a great shift in ensuring food security.