Functional compatibility of two arbuscular mycorrhizae with thirteen fruittrees in Senegal

Functional compatibility between thirteen tropical fruit trees (Afzelia afr icana Smith., Adansonia digitata L., Aphania senegalensis Radlk., Anacardiu m occidentale L., Cordyla pinnata (Lepr. ex A. Rich.) Milne-Redhead, Dialiu m guineensis Wild., Landolphia heudelottii A.DC., Sclerocarya birrea (A,Roc h.) Hochst., Saba senegalensis (A. DC.) Pichon and four reference hosts Bal anites aegyptiaca (L.) Del., Parkia biglobosa (Jacq.), Tamarindus indica L. and Zizyphus mauritiana Lam.) and two arbuscular mycorrhizal fungi (AMF) ( Glomus aggregatum Schenck and Smith emend. Schenck and Glomus intraradices Schenck and Smith), was investigated. Marked differences were found between them in terms of mycorrhizal formation, root colonization, relative mycorr hizal dependency (RMD) and phosphorus concentrations in shoot tissues. A. a fricana, L. heudelottii and S. senegalensis did not form symbiotic associat ions, and the growth of A. africana decreased following mycorrhizal inocula tion, while L. heudelottii and S. senegalensis showed no dependency. In con trast, A. digitata, A. senegalensis, A. occidentale, B. aegyptiaca and S. b irrea were well colonized with AMF, but did not significantly increase in b iomass production. Five fruit trees did, however, show dependency by a posi tive interaction with G. aggregatum, the most effective AMF. Z. mauritiana was found to be very highly dependent (RMD > 75%), T. indica was highly dep endent (50-75% RMD), and D. guineensis, P. biglobosa and C. pinnata were mo derately dependent (25-50% RMD). Phosphorus absorption probably contributed to this dependency more than the absorption of potassium. These results in dicate that some tropical fruit trees do derive benefits from AM inoculatio n, while others do not.