Multiple criteria-based screening of Trichoderma isolates for biological control of Botrytis cinerea on tomato

Seventy-two Trichoderma isolates were obtained from Hubei Province of China and identified to 11 species based on rDNA-ITS. The isolates were initially tested for invasive growth on Botrytis cinerea colony in dual cultures with B. cinerea on potato dextrose agar at 20 degrees C. The resulting 28 isolates were further determined for biocontrol potential using three criteria: invasive growth on Botrytis cinerea colonies at 15 degrees C, antifungal activity and promotion of tomato seed germination. Performance of the Trichoderma isolates was scored and the total scores were used to select isolates with the highest biocontrol potential. Four selected isolates (T. harzianum: T-21 and T-68; T. koningiopsis: T-35 and T-51) were evaluated for growth-promoting and resistance-inducing effects on tomato seedlings, and for sporulation-suppressing effect on B. cinerea on dead tomato leaves. All the four isolates significantly (P < 0.05) promoted tomato growth possibly through producing gibberellins and indole-3-acetic acid, and induced systemic resistance against B. cinerea. Isolates T-21, T-51 and T-68 suppressed B. cinerea sporulation by 62.8, 66.1 and 63.7%, respectively, compared to the control treatment. This study suggests that the multiple criteria-based procedure is rational for screening of Trichoderma isolates against B. cinerea, and T. koningiopsis T-51 is a promising biocontrol agent. (C) 2016 Elsevier Inc. All rights reserved.