POTENTIAL OF Trichoderma viride AND Rhizobium leguminosarum IN COMBINATION WITH TOPSIN M70 FUNGICIDE FOR MANAGEMENT DAMPING-OFF DISEASE OF PEA PLANTS CAUSED BY Rhizoctonia solani

Abstract

Efficacies of Trichoderma viride, Rhizobium leguminosarum and the fungicide Topsin M70% individually and/or their mixtures were tested in vitro and greenhouse conditions to control damping-off and root rot diseases of pea plants (Pisum sativum L., cv. Master P) caused by Rhizoctonia solani. The ability of tested Rhizobium leguminosarum and Trichodermia viride to exhibit plant growth promoting rhizobacteria (PGPR)-properties including ability to solubilize-P and production of IAA, as well as production of siderophores, hydrocyanic acid (HCN) and secretion of cell-wall degrading enzymes (chitinase and protease) were investigated. Also, under in vitro conditions the effect of Topsin M70% on growth of R. solani and T. viride, R. leguminosarum and their mixtures was determined. The fungicide effective concentration was found to range from 10 to 50 ppm for R. solani and T. viride mycelial growth being 83.30, 100, 76.08 and 100% at 40 and 50 ppm of Topsin M70%. The same trend was obtained with R. leguminosarum that showed maximum tolerance at 40 and 50 ppm of Topsin M70% with the average of 52.19 and 59.85% inhibition over control, respectively. Additionally, greenhouse conditions were conducted on sandy clay soil at Etay El Baroud Agricultural Research Station, Beheria Government, Egypt to study the singly effect of seed soaking in T. viride, R. leguminosarum or their mixtures with the soil drench fungicide in pots after sowing of pea cv. Master P in concern. Significant decrease of damping-off and root rot of pea was obtained. Numbers of survived plants, shoot length as well as, fresh and dry weight were recorded. The combined treatments R. leguminosarum + Topsin M70%, T. viride + Topsin M70% and R. leguminosarum + T. viride + Topsin M70% were the most effective ones resulting the least percentage of total dampingoff and the highest percentage of healthy plants being 96.67 and100.00%, respectively. Seed treatment with T. viride, R. leguminosarum and drenched fungicide individually or in mixture improved plant growth as indicated by the increased growth parameters and the physiological activities (phytosynthetic pigments, peroxidase and polyphenol oxidase), especially in combined treatments. Peroxidase and polyphenol oxidase activities were increased in the different treatments-even, the fungicide drench treatment. Reduction in total damping-off was positively correlated with both peroxidase (R 2 = 96.70, P ˂ 0.005) and polyphenol oxidase (R 2 = 89.60, P ˂ 0.005) activities.