Free-living nematodes associated with kiwifruit and effect of soil chemical properties on their diversity

Kiwifruit (Actinidia species), a temperate plant, is becoming one of the most important crops in tropical regions of high altitudes at Limpopo Province, South Africa. During a survey on free-living nematodes in five kiwifruit orchards, 19 nematode species were identified from the soil samples across five kiwi orchards at Limpopo Province. Overall, the most prevalent nematodes encountered were Rhabditis species, followed by Cephalobus persegnis and Aporcelaimellus with 46.37, 45.12 and 18.29% frequency of occurrence, respectively. Prominence Values (PVs) of Rhabditis sp. (17834.40) and C. persegnis (14329.70) were higher when as compared to those of other free-living nematode species. The results indicated no significant correlation between the free-living nematode species and pH, except for Plectus aquatilis. However, Ca% had a significant positive correlation with C. persegnis, Acrobeles complexus, Clarkus papillatus, Trypilina, Diptherophora, Prismatolaimus and Aporcelaimellus. In contrast, Na and Ca exhibited a significant positive correlation with P. rigidus. In conclusion, the high altitude-kiwifruit-producing regions suggested the existence of a considerable range of free-living nematodes, with the highest nematode diversity in Nooyenskopje orchards.