Determination of Spore Germination Inhibition Activity

Spore germination of P. microspora was detected with minor modifications as described by Pane et al. (2016). A volume of 20 μL of spore suspension containing 1 × 10⁶ spores mL⁻¹ was incorporated into PDA mediums with 100 μL various concentrations of GO at 0, 2, 4, 6, 8, 10, and 12 μL per mL propylene glycol, respectively, and then cultured at 28°C for 7 h. The spore germination was observed by microscopy. The germination was determined when the length of a germ tube exceeded half of the small-end diameter of the spore, and at least 200 spores were examined in each visual field before determination. Spore germination rate was expressed as percentage of the germinated spores to the total calculated spores, and the inhibitory rate of spore germination was calculated by the following formula:

where IR_sg was the inhibitory rate of spore germination, %;

IR_t and IR_c were represented as the inhibitory rate of spore germination at control and at GO treatment, respectively.

Each replicate consisted of three observations, and three replicates were performed for each treatment.