In vitro SELECTION OF MOROCCAN PHOSPHATE SITES’ Trichoderma ISOLATES ACCORDING TO THEIR ANTAGONISM AGAINST THE WHEAT AND BARLEY ROOT ROT PATHOGENS

The biocontrol abilities of Trichoderma isolates isolated from soil and roots collected from adjacent sites to the Khouribga and Benguerir Phosphate mines (Morocco) were tested in vitro by dual culture against different pathogens responsible for root rots in wheat and barley plants (Bipolaris, Curvularia and Fusarium) in the in vitro assays. Under in vitro conditions, Trichoderma isolates T1; 1TH; TR-EM 2; TR-B 98 (1); TR-B 98 (2); TR-B 98 (3) were more efficacious and they give significant inhibition of both mycelial growth and germination of the seven pathogens studied through the production of volatile metabolites and mycoparasitic capacity. A maximum percentage exceeding 70% was recorded. Moreover, direct confrontation tests showed a great ability of five isolates of Trichoderma species to colonize the medium in competition with pathogenic fungi exhibiting colonization percentages in the range of 49.33 to 75.43%. However, all pathogen isolates were comparatively less inhibited by all the species of Trichoderma by producing diffusible no-volatile compounds with percentages of growth and germination inhibition lower than 29.5 and 20.5% respectively.