RELATIONSHIPS BETWEEN ENVIRONMENTAL-FACTORS AND LEVELS OF MYCORRHIZALINFECTION OF CITRUS ON 4 ISLANDS IN THE EASTERN CARIBBEAN

Citrus root and soil samples were collected from the Caribbean islands of Barbados, Dominica, Grenada, and St Lucia. The roots were examined for the presence of vesicular-arbuscular mycorrhizal (VAM) fungi and the soil samples analysed to determine pH; percentage of organic matte r; and Ca, Mg, K, N, P, S, B, Cu, Fe, Mn, and Zn contents. The age of the trees sampled, the altitude of each site, and its annual rainfall were also recorded. The significant correlations found between measure s of VAM fungal infection and site characteristics varied between isla nds. For each island, multiple regression equations were developed to predict levels of VAM fungal colonization of the roots on the basis of site characteristics. Plant health and degree of VAM fungal infection were related; the healthiest plants were the most highly colonized.