Occurrence of vesicular-arbuscular mycorrhizal fungi in citrus in the states of Bahia and Sergipe,Brazil

Abstract

The occurrence of vesicular-arbuscular mycorrhizal (VAM) fungi was evaluated in rhizosphere samples of citrus in nine orchards and seven nurseries distributed among the three main producing areas in the states of Bahia and Sergipe, Brazil. The orchard plants of 'Pêra' Sweet orange (Citrus sinensis L. Osbeck) grafted on Rangpur lime (C. limonia Osbeck) rootstock were six to eight years old and the nursery plants were eight to ten months old. Multiple random samples of rhizospheric soil were taken to assess the chemical and physical properties, as well as VAM spore density, and rootlets samples were collected to estimate the intensity of mycorrhizal colonization. In general the rootlets colonization and spore density were higher in low fertility soils. The relative occurrence of species decreased in the following order: Acaulospora scrobiculata, Acaulospora spinosa, Glomus occultum, Glomus etunicatum, Acaulospora longula, Gigaspora margarita, Acaulospora appendicula, Acaulospora morrowae, Scutellospora heterogama, Scutellospora pellucida. The occurrence of some species of VAM fungi was influenced by chemical characteristics and textural classes of the soil.