Screening test for antagonism
Trichoderma spp. Isolates and Fusarium oxysporum f.sp. lycopersici were cultured in order to observe the interaction between them. They were cultivated separately for 5 days on PDA culture medium, then colonies of Trichoderma spp. and Fusarium oxysporum f.sp. lycopersici were point inoculated in pairs 3 cm apart from each other on PDA plates. The controls consisted of pure Fusarium oxysporum f.sp. lycopersici cultures. The experiment was performed three times, the plates were placed in an incubator at 28 °C ±1 °C, and the development of the colonies was observed until the controls covered the whole potato dextrose agar (PDA) surface.
Statistics
The coefficient of antagonism was calculated using the following formula:
N = (LC - LP) / LC
Where, N is the coefficient of antagonism, LC is the radius of the control colony and LP is the radius of Fusarium oxysporum f.sp. lycopersici in dual culture colony.
Morphological identification of Trichoderma spp. isolates
The Trichoderma spp. isolates were cultured on PDA for 7 days at 28 °C ±1 °C. The colonies morphology and feature were observed, which include spore morphology, length of conidiophores and conidia. Slides were sealed with nail polish and examined under microscope.