Effects of arbuscular mycorrhizal fungi on severity of root rot of bananas caused by Cylindrocladium spathiphylli

The interaction between four arbuscular mycorrhizal (AM) fungi, #Glomus sp.#, #G. proliferum#, #G. intraradices# and #G. versiforme#, and the root-rot fungus #Cylindrocladium spathiphylli#, and subsequent effects on growth and phosphorus nutrition of banana (#Musa acuminata#, AAA, cv. 'Grande Naine') were investigated under glasshouse conditions. Overall, root infection by #C. spathiphylli# reduced the growth of banana plants, but preinoculation with AM fungi significantly attenuated this detrimental effect. Lower disease severity, stimulation of growth and increase of shoot P content were observed for the plants inoculated with one of the four AM fungi. #Glomus sp.# and #G. proliferum# induced the largest increase in growth parameters and shoot P content as compared to #G. intraradices# and #G. versiforme#, in the presence as well as in the absence of #G. spathiphylli#. Root damage caused by #C. spathiphylli# was decreased in the presence of AM fungi, but the inoculation of mycorrhizal plants with #C. spathiphylli# also decreased the intensity of AM fungal root colonization, indicating a clear interaction between the two organisms. (Résumé d'auteur