Biological and mathematical description of the growth pattern of Fusarium oxysporum in a sterilized soil

The population dynamics of 4 F. oxysporum strains incubated in sterilized soil have been studied for 35 days. Enumeration of fungal propagules was carried out by the soil dilution plate technique. The qualitative variations of the populations were viewed by epifluorescent microscopy after staining the fungal propagules in soil with Calcofluor. A logistic model was used to describe population dynamic parameters. The predominant mode of growth of F. oxysporum in sterilized soil involved abundant production of conidia during the exponential phase. The increase of the propagules resulting from mycelial development during the lag phase was not taken into account by the logistic model. By determining the density of the population at the end of the lag phase, growth parameters of different F. oxysporum strains have been identified allowing the saprophytic competence of each strain to be characterized.