Effect of pre-crops on the inoculum potential of arbuscular mycorrhizal fungi and cassava yield

The effect of pre-crops on the inoculum potential (IP) of arbuscular mycorr hizal fungi (AMF) and yield of cassava was evaluated on a Red-Yellow Podzol ic soil in the field. The experiment was carried out at Embrapa-Centro Naci onal de Pesquisa de Agrobiologia (CNPAB), Seropedica, RJ, Brazil, in plots with 30 m(2) arranged in a randomised block design with four replications. As pre-crops, four legume species were used: Canavalia ensiformis, Mucuna a terrina, Crotalaria juncea and Cajanus color; and a grass Sorghum bicolor ( BR 005) in relation to plots, without plants. After a grow period of 82 day s, at the same plots, cassava stakes were planted, which were grown for eig ht months. The yield of cassava roots ranged from 12.76 to 17.20 ton ha(-1) , although no statistical significant effects were found between the treatm ents. There were 16 AMF species identified, and some of them had a signific ant frequency changement after the growing cycles. The number of infective propagules were significantly increased after sorghum crop in relation to p lots without plants. It was showed that identification of plant species cap able to increase the IP in the field soils may be a good alternative way to solve the problem of inoculum production to mycotrophic crops in the field .