Sensibilité du haricot Phaseolus vulgaris à la concentration en aluminium des sols de la région des grands lacs

Abstract

Sensibility to soil aluminium concentration of the common bean Phaseolus vulgaris in the African "Great Lakes" region. The climate of the African region around the "Great Lakes" induces a strong process of soil weathering which eventually leads to a strong aluminium saturation of the absorption complex, as expressed by the "m" index of Kamprath. The response to aluminium toxicity of the common bean cv. Diacol Calima, a widely grown variety in Burundi, has been studied in pot trials in two ways : (1) Using superficial soil samples of "humiferous high elevation kaolisols" whose "m" index varied between 4 and 92 ; (2) On culture condition consisting of an inert substrate complemented with a nutritional solution to which a serie of soluble aluminium concentrations were added. Under soil condition, biomass produced after a period of 25 days of growth, decreased as from "m" = 33. The number of Rhizobium nodules decreased drastically with aluminium toxicity becoming negligible at "m" - 33. On culture media, rising concentration of aluminium affected growth adversely as well, although root growth inhibition was less pronounced than under soil condition.