2.3 Inhibition of hyphal growth and spore germination in vitro The hyphal growth of C. gloeosporioides in the presence of the yeast I. orientalis was observed. Three 7-mm-diameter agar discs taken from a 10-day-old PDA culture of C. gloeosporioides were transferred to 20 mL of potato and dextrose broth (PDB) in Petri dishes. Yeast cell suspension at a concentration of 2.8×108 cells/mL, prepared from 4-day-old PDA culture, was then added into the Petri dishes at different volumes (0.1, 0.5 and 1.0
mL). Sterile distilled water was used in the control treatment. There were ten replicated Petri dishes in each treatment. The Petri dishes were incubated at room temperature for 15 days. Dried weight of hyphal mass was collected from each treatment and compared to the control treatment. Inhibition of spore germination of C. gloeosporioides by the yeast I. orientalis was evaluated. Spore suspension of C. gloeosporioides was prepared from 10-day-old PDA culture at concentration of 6.4×108 spores/mL. A cell suspension of the yeast I. orientalis was prepared from 4-day-old PDA culture at a concentration of 3.3×108 cells/ mL. These two suspensions were then added, 1 mL spores and 0.2 mL yeast, into a flask containing 10 mL of PDB. There were 3 replications for each treatment. After 12 h of incubation at room temperature, spore germination of C. gloeosporioides was counted using a haemacytometer (BOECO, Germany) under light microscope (National, model 173MS, China)