Inoculação de Fusarium oxysporum f. sp. phaseoli em sementes de feijoeiro através de restrição hídrica

Abstract

The objective of the present work was to test methodology of inoculation of bean seeds with Fusarium oxysporum f. sp. phaseoli using water restriction technique. For that, three solutes, sucrose, potassium chloride and manitol, added to the medium potato-sucrose-agar, PSA at three water potentials (-0.8, -1.0, -1.2 MPa) and four duration periods of the exposition of seeds to the fungus (36, 72, 108 and 144h) were used. The effects of the fungus on the performance of the seeds and emerged plants were evaluated looking at germination and health (blotter-test). The mycelial growth of the fungus in vitro, was not reduced by any osmotic treatment. Higher growth of the fungus was observed at osmotic potentials of -0.8 e -1.0 MPa. At longer durations of exposition of the seeds to the pathogen, 108 e 144h, mycelial growth of the fungus was higher and affected seed performance. The greatest mean incidence of Fusarium oxysporum f. sp. phaseoli (64%) was detected on seeds in wich KCl was used. At 144h of inoculation period on that solute, the incidence was of 70%.