European Journal of Sustainable Agroecosystems

Background: Ralstonia solanacearum is the causative agent of bacterial wilt, one of the most severe diseases of tomato (Solanum lycopersicum L.) worldwide, which causes substantial economic losses. Endophytic bacteria especially Pseudomonas fluorescens have antimicrobial and plant growth promoting properties to inhibit pathogenic bacteria as well as to enhance host defense mechanisms and plant productivity. Thus, providing a sustainable alternative to chemical disease control.
Objective: This research investigated the potential of a native endophytic isolate of Pseudomonas fluorescens for the biocontrol of bacterial wilt, enhancement of the physiology of plants, improvement of soil biological activity, and higher yield of tomato under greenhouse and field conditions.
Methods: For the purpose of finding out the effectiveness of Pseudomonas fluorescens and strain on controlling Ralstonia solanacearum in tomatoes, greenhouse and field experiments were conducted using Chosen tomato seedlings treated with Pseudomonas fluorescens in three different methods. All of the above-mentioned parameters like disease incidence, severity, wilt reduction percentage, and biocontrol efficiency were evaluated. Furthermore, growth status and morphology, SOD, CAT, POD and APX, PAL, PPO, chitinase and β-1,3-glucanase were assessed in addition to the effect on rhizosphere microbes, soil enzymes and fruit yield and quality.
Results: The use of Pseudomonas fluorescens resulted in a reduction of bacterial wilt incidence by 56% to 72% and disease severity by 63% to 78% as compared to the control treated with no bacteria. The plants that were treated showed an increase in plant height, leaf area, shoot and root weight, and the total of dry matter. The physiological tests conducted proved that the amount of chlorophyll increased, relative water, and proline amounts appeared to increase, thus confirming that the plants can endure the stress. The capacity of the antioxidant enzymes as well as other enzymes related to the immunity was increased showing that the plants were prepared to resist the disease. The quantity of the microbes in the soil and activities of the enzymes increased as well. The amount of fruits increased by 45% to 58% as well as the quality of the fruit in comparison to the gardening.
Conclusion: The isolate of indigenous endophytic Pseudomonas fluorescens managed to suppress the bacterial wilt disease and stimulate the plant defense mechanisms, soil biological activity as well as the productivity of tomatoes. The capacity of Pseudomonas fluorescens to trigger systemic resistance and foster positive rhizosphere processes and the crop performance proves its ability to serve as an environmentally sustainable biocontrol agent that can be used in the implementation of tomato production processes and the management of bacterial wilt.