2.3. In vitro antifungal assays
In order to evaluate the inhibitory effects of extracts on in-vitro growth of A. alternata, each filtrate was poured onto 0.1 Czapek Dox solid medium (Czapek Dox Broth 3.4 g L1, Agar 15 g L1), to reach the final concentrations of 5, 10 and 25 mg mL1, into Petri dishes (3 cm diameter).
A fungal plug (0.5 cm diameter) from a Czapek fungal growing sub-culture was placed upside down on the centre of each plate.
Non-amended plates were used as controls.
Plates were inoculated in triplicate and incubated in the dark at 25 C.
The radius of each colony was measured when the fungi reached the edge of the control plates.
Fungal growth under treatments was expressed as a percentage with respect to that observed in untreated control plates, calculated with the formula: Fungal growth % ¼ 100 [radius on the treatment/radius on thecontrol].
The effects of extracts on A. alternata conidial germination were assessed by a liquid microculture method. Each filter-sterilized extract was diluted into 0.1 Czapek Dox Broth (3.4 g L1) to reach the final concentrations of 5, 10 and 25 mg mL1; 100 mL of these suspensions were then pipetted in each well (96-well microplate) for three replications.
Non-amended Czapek Dox Broth was used in untreated control wells. Afterwards, 10 mL ofconidial suspension (1 105 conidia mL1) were inoculated into all the wells.
After 24 h-incubation at 25 C, at least 100 spores were observed microscopically to determine the germination rate.
Conidia germination under treatments was expressed as a percentage of that observed in untreated control wells, calculated with the formula: Germinated conidia % ¼ 100 [germination rate on the treatment/germination rate on the control].
The experiments were performed twice.