Rhizosphere soil samples were collected in a semiarid area, in the region of the São Francisco River valley, Petrolina, Pernambuco state, Brazil, to study the diversity of filamentous fungi in a soil cultivated with melon (Cucumis melo L. cv. Gold Mine) and receiving different organic amendments: Treatment 1 (control, without organic compost); T2 (77% coconut fiber, 20% goat manure and 3% K2SO4); T3 (10% Ricinus communis leaves and stems, 50% Pennisetum purpureum leaves and 40% goat manure); T4 (77% coconut fiber, 20% goat manure and 3% termophosphate); T5 (47% Pennisetum purpureum leaves, 50% goat manure and 3% K2SO4); and T6 (57% Pennisetum purpureum leaves, 40% goat manure and 3% termophosphate). Fungal isolation was carried out by the serial dilution technique to 1:1000. The Sorensen index of similarity, frequency and distribution of the fungi were evaluated. Seventy-eight species of filamentous fungi were isolated and identified, plus several Basidiomycota (04) and Mycelia sterilia (02). The predominant genera were Aspergillus and Penicillium, with 15 and 13 species, respectively. A greater number of species was found in the sowing period (49), and in relation to the organic fertilization, treatment 6 provided the greatest species diversity (43 species). Most of the species are saprobes and only a few are considered to be potential pathogens on melon plants, such as Fusarium oxysporum, F. solani and Myrothecium roridum.
semiarid; São Francisco River valley; soil amendments; microorganism
