Fusarium verticillioides inoculum potential influences soybean seed quality

F. verticillioides (FVE) is an important Fusarium species that has been recovered from soybean seeds. In other crops, such as maize, it has the potential to decrease seed germination and vigor. The objective of this study was to evaluate the influence of seed inoculum potential (amount of inoculum present in seeds) of FVE on soybean seed quality, as measured by germination of artificially inoculated seeds. Seeds were inoculated with 2.5 x 10(6) FVE conidia/ml for one minute as the low inoculum potential seed treatment. For the high inoculum potential seed treatment, inoculated seeds were inoculated with the same conidia suspension, but osmoconditioned on potato dextrose agar +8% mannitol for 48 h. Two soybean genotypes, 'AG3039' and 'KSU3406' were tested. Analysis of seeds inoculated with the low inoculum potential treatment showed that none of the FVE isolates tested and only the positive controls were able to significantly reduce soybean seed germination (P < 0.001) when compared with the mock-inoculated control for both genotypes tested. Under the high inoculum potential treatment, all three FVE isolates were able to decrease seed germination when compared with the mock-inoculated control treatment for both genotypes. This study suggests that F. verticillioides has the potential to reduce soybean seed quality, depending on the amount of inoculum present in seeds (inoculum potential), which affects pathogenicity and negatively influences soybean seed germination as well as the establishment of a uniform and healthy stand in the field.