Fluorescent pseudomonads associated with vegetables under organic practices

Abstract

Diversity of fluorescent pseudomonads associated with lettuce, carrot and cucumber under organic practices was studied. The experimental design was random blocks, with three replicates. Prior to planting, 20 t/ha of cattle manure and 1,5 t/ha of thermophosphate were applied to the soil. Soil samples were separated into rhizosphere, rhizoplane, roots and phylloplane of the crops. Bacterial isolates which presented fluorescence under UV light were selected. These isolates were classified accordingly to their colony morphology. One isolate from one of the quantitatively most representative groups was identifiedby the API 20 NE system. Twenty-five isolates were selected, identified as P. putida, from ectorhizosphere, rhizoplane, phylloplane e endorhizosphere of the three plant species for RAPD characterization. The phenotypic analysis allowed the identification of certain groups of isolates associated with lettuce, carrot and cucumber. There is a high diversity of strains, revealed by genotypic and phenotypic characterization, associated with vegetables studied under organic production system.