Identification of soil factors that relate to plant parasitic nematode communities on tomato and yam in the French West Indies

A soil and nematode survey of tomato and yam crops was made in Martinique (French West Indies). Each sample was divided into two parts, one for the nematode study and one for the soil analysis. The coupling of the data was made using the coinertia analysis. For tomato plants which were grown from seeds, the nematode-soil relationships were very strong. For the two varieties of yams, Dioscorea cayenensis-rotundata and D. alata, whose infested seed tubers carry nematodes into the field, the relationships were weaker and depended on the yam variety. For D. cayenensis-rotundata, which was attacked by the endemic parasite Pratylenchus coffeae, the relationship between nematode community and soil type was strong. For D. alata, this relationship was weaker because it is mainly parasitised by the exotic species, Scutellonema bradys, which is exclusively introduced into the field with the seed tuber, whatever the soil type. Soil texture was the most important factor explaining the presence of some species. However, Meloidogyne spp. and the ectoparasitic species such as Xiphinema spp. were associated with light andosols; Aorolaimus luci needed, in addition, higher levels of organic matter. P. coffeae preferred any type of soil rich in organic matter and its abundance seemed influenced by calcium and magnesium content or pH. In contrast, P. brachyurus did not appear to be sensitive to any of the measured physico-chemical soil characteristics. (C) 1998 Published by Elsevier Science B.V. All rights reserved.