Abstract
Twenty sorghum seed samples were collected in 2015 from sorghum fields in southern region of Saudi Arabia and investigated for seed-borne fungi. Thirteen fungal genera and twenty-one fungal species were recorded on sorghum seeds using agar plate technique. Fusarium verticillioides was the most common pathogenic fungus in the present survey. In a trial to find out dual-purpose microorganisms, which able to stimulate sorghum growth and control its pathogens with friendly environmental impact 6 species of Trichoderma were evaluated. One of them was selected and identified as T. harzianum 1-SSR. The high production of indole-3-acetic acid (IAA, 52.57 mu g/ml), and total phenols (53.30 mu g/ml) as well as the reasonable amount of gibberellic acid (AG3, 34.80 mu g/ml) during fermentation process and the reduction of the final culture pH (4.6) compared to other Trichoderma isolates introduced explanation for such choice. Under laboratory, Trichoderma bioactive compounds (TBA) reduced total infection on sorghum seeds, especially F. verticillioides that was completely inhibited and colonized by T harzianum. Inoculation with T. harzianum and/or its TBA reduced the pre- and post-emergence damping-off, increased growth and phenol content of sorghum seedling. This in turn may encourage the practical application of such dual-purpose fungus on large scale.