Resumo

CORTES-SARABIA, J et al. Seasonality and Rhizosphere Microorganisms of Ilama (Annona diversifolia Saff.) in Natural Orchards in the Dry Tropics. Terra Latinoam [online]. 2009, vol.27, n.1, pp.27-34. ISSN 2395-8030.

The ilama (Annona diversifolia Saff.) is a native tropical plant from Southwestern Mexico and Central America of great regional importance due to the high quality of their fruit. Despite its importance, rhizosphere microorganisms and mycorrhizal fungi of ilama have not been studied. Furthermore, studies related to the influence of seasonality on rhizosphere microorganisms in tropical areas are insufficient. In the present study, the populations of rhizosphere microorganisms, including arbuscular mycorrhizal fungi, associated with three plant ages and four seasons of the year were evaluated. The populations of nitrogen fixing and P-solubilizing bacteria were higher in the months with the highest precipitation. In contrast, the populations of fungi and actinomycetes were higher in the dry season. The highest mycorrhizal colonization in ilama plants was observed in the month with the highest precipitation (August) in 1 to 8 month-old and 4 to 20 year-old plants. The highest density of spores was observed in the season without precipitation and with low temperature. This is the first study of rhizosphere microorganisms associated with Annona diversifolia and one of the few studies where the influence of seasonality on rhizosphere microorganisms is analyzed in tropical trees. This study shows that the populations of rhizosphere microorganisms were differentially affected by seasonality and by nutrient demand of plants.

Palavras-chave : defoliation; arbuscular mycorrhiza; microbial communities; Annonaceae; abiotic factors.