Activation of Tomato Plant Defense Response Against Fusarium Wilt Disease Using Trichoderma Harzianum and Salicylic Acid under Greenhouse Conditions

Defense system of the plant against pathogen attach is the ultimate goal of any controlling process of the pathogen. Biological control and hormonal inducers represents an interesting strategy to stimulate the defense system of the plant especially when applied together. In the present work Trichoderma.Harzianum, salicylic acid and low dose of thiophanate methyl as recommended fungicide were used as a new strategy to enhance tomato defense response against wilt disease caused by Fusarium oxysporum f. sp. Lycopersici under greenhouse conditions. Changes in various physiological defenses including enzymes like polyphenol oxidase (PPO), peroxidase (POD) and acid invertase (AI); total soluble phenols; protein and chlorophyll content were investigated. In the present study, tomato plants infected by Fusarium oxysporum f. sp. Lycopersici one week after inoculated with Trichoderma Harzianum (TH) fungi (seedling root dipping and/ or soil treatment) and/ or sprayed daily for one week with hormonal inducer (SA). Plants were harvested at 35 days after pathogen infection. All applied treatments completely protected tomato seedlings against Fusarium wilt. Disease index percentage (DI%) was highly significantly reduced up to zero%. Level of all the determined physiological parameters greatly changed in tomato plants in response to Fusarium oxysporum (FO), TH fungi and hormonal elicitor and reflected many components of defense signals which leading to the activation of power defense system in tomato against pathogen attack. Application of Trichoderma harzianum and salicylic acid stimulated all these parameters not only to reach but also exceed their content in healthy control.