Interação entre fungos micorrízicos arbusculares e Pratylenchus coffeae na produção de mudas de gravioleira (Annona muricata)

The sudden death of soursop (Annona muricata), caused by the lesion nematode Pratylenchus coffeae is an important disease in Northeastern Brazil. Transplanting health young soursop trees is one of the control measures recommended; however, early mycorrhizal inoculation of seedlings in the nursery could protect the young trees and reduce the severity of the disease in nematode-infested fields. The objective of this work was to evaluate the interaction between arbuscular mycorrhizal fungi (AMF) and P. coffeae on soursop var. Morada seedlings under greenhouse conditions. The experiment was carried out in a completely randomized design with factorial of 4 (control without AMF; inoculation with 200 spores/pot of Glomus etunicatum, Acaulospora longula, and AMF indigenous in the rhizosphere of soursop) x 2 (control and inoculation of 3200 juveniles plus adults of Pratylenchus coffeae), with five replicates. The nematode was inoculated 90 days after AMF inoculation. Evaluations were carried out sixty days after nematode inoculation based on plant height, fresh root mass, fresh and dry shoot matter, root colonization, AMF spore density and number of nematodes in the roots and in the soil. The growth of soursop seedlings was not affected by P. coffeae. In the treatments without nematodes, the seedlings associated to AMF presented significant increase on height and root and shoot mass. In the presence of the nematode, the native AMF induced growth increase, when compared to control. Root colonization by AMF was not affected by the nematode; but AMF sporulation sometimes increased in presence of P. coffeae. The AMF did not suppress nematode reproduction in roots and soil.