ALTERNATIVE FOR ARBUSCULAR MYCORRHIZAL FU NGI INOCULUM PRODUCTION IN AEROPONIC CULTURE

The generalized use of arbuscular mycorrhizal fungi (AMF) has been qui te limited, due to obligatory biotrophic character of these microorgan isms, which demand the use of metabolically active roots for their mul tiplication. The present work was conducted to evaluate the possibilit y of AMF inoculum production using an aeroponic system constituted by a tank with 200 l of nutritive solution pulverizing the root plants th rough various micro-irrigation nozzles. The initial results showed tha t, during the first 28 days of cultivation, the plants suffered an ada ptation stress, with a significant reduction of the root colonization rate and spore number. However, after this adaptation period, the AMF colonization rates increased significantly, stabilizing at 56 to 72 da ys in sweet potato plants inoculated with Entrophosphora colombiana, w ith 72% of colonization. The number of spores recovered in the root sy stem of plants infected with E. colombiana was surprising, with values of 5,082 and 156,336 spores per gram of root dry matter at 70 and 98 days, respectively. However, with Gigaspora margarita and Glomus etuni catum, these values were lower than expected, showing the need of an a daptation of the aeroponic technique for these species.