Effects of Pseudomonas fluorescens on the disease severity, physiological, and biochemical traits in the tubers of potato cultivars infected with Rhizoctonia solani under greenhouse conditions

To evaluate the effects of Pseudomonas fluorescens on potato production in the presence of Rhizoctonia solani, a three replicated greenhouse experiment was conducted in a completely randomized factorial design containing three strains of Pseudomonas fluorescens including UTPF5 (P5), P. fluorescens UTPF68 (P68) and P. fluorescens UTPF74 (P74), Rhizoctonia solani AG3 and Agria and Sante cultivars of potato provided by the seed and plant certification and registration institute. Disease severity, root dry weight, stolon length and dry weight, tubers number, dry weight and fresh weight, Antioxidant activity (GPX,
-1, 3-glucanase), proline content, MDA and soluble sugar content were determined in different treatments. The results showed that Pseudomonas fluorescens treatment had a significant effect on all traits in the presence of fungus (pathogeninfected condition). The fungal virulence was also significantly decreased in this treatment compared to the control. P5 and Sante variety combined treatment showed highly significant effect on the measured traits than the other combined treatments, so that the highest amounts of dry weight of root, stolon length and dry weight, tubers dry and fresh weight and the number of stolon were observed in this treatment with 0.62, 0.86, 1.40, 2.31, 1.37 and 0.63 folds increase respectively compared to the control. Results also indicated that in P5 treatment Antioxidant enzyme activity, (GPX,
-1, 3-glucanase), proline and soluble sugar content were increased by 1.32, 0.61, 2 and 2.6 and folds respectively and lipid peroxidation was decreased by 53% in comparison with the control.