Plant parasitic nematode populations on upland and hydromorphic rice in Côte d'Ivoire: Relationship with moisture availability and crop development on a valley slope

Abstract

The influence of underlying hydrology and overhead irrigation on plant parasitic nematode populations in upland and hydromorphic rice was examined during three successive seasons on a valley slope at the West Africa Rice Development Association station, Côte d'Ivoire. Nematode population densities and species composition were clearly affected by hydrology. Nematode populations in hydromorphic rice were characterised by Basiria spp., Coslenchus spp. and Filenchus spp. (combined) and Paratrichodorus minor. Upland rice was characterised by Scutellonema clathricaudatum, Pratylenchus zeae, and Mesocriconema tescorum. Rotylenchulus spp. and Heterodera sacchari being concentrated in the lower upland rice area whereas Helicotylenchus spp. and Meloidogyne incognita, were distributed over the hill slope. For many species peak population density shifted, relative to the slope, between sowing and harvest. Excepting the disappearance of rarer species, only H. sacchari population densities were correlated with time, increasing with duration of the experiment. There was little evidence that overhead irrigation had any influence on nematode species composition, but it influenced population densities of ectoparasitic nematodes and had a strong positive influence on yield. Yield was also positively correlated with proximity to the water table and declined as the experiment progressed. Because of the complexity of nematode communities it was difficult to determine the effects of individual species on plant growth characters or yield. © 2001 Elsevier Science B.V.