ISHS Acta Horticulturae 635: XXVI International Horticultural Congress: Managing Soil-Borne Pathogens: A Sound Rhizosphere to Improve Productivity in Intensive Horticultural Systems
EVALUATION OF PAENIBACILLUS POLYMYXA PKB1 FOR BIOCONTROL OF PYTHIUM DISEASE OF CUCUMBER IN A HYDROPONIC SYSTEM |
| Authors: | J. Yang, P.D. Kharbanda, M. Mirza |
| Keywords: | Bacillus polymyxa, bacterium, biocontrol agent, seedless cucumber, root rot |
| DOI: | 10.17660/ActaHortic.2004.635.7 |
| Abstract:
Seedling blight and root rot caused by Pythium spp. is an important disease in greenhouse cucumber plants. Growers suffer considerable economic losses due to the disease every year. Effectiveness of the bacterium Paenibacillus polymyxa PKB1 was evaluated for its ability to protect cucumber plants against Pythium spp. in vitro and in hydroponic systems in a greenhouse. In the in vitro test, P. polymyxa PKB1 showed inhibitory effect against nine Pythium strains isolated from cucumber roots, on potato dextrose agar and nutrient agar plates. P. polymyxa PKB1-coated cucumber seeds had significantly higher germination and survival rates than un-coated seeds when tested against Pythium spp. on water agar plates. In the greenhouse test, the bacterium was added at the rate of 1 x 106 - 1 x 108 spores ml-1 to the circulated and non-circulated hydroponic systems. The bacterium survived in the nutrient solution, colonized plant roots, rockwool blocks and significantly reduced the disease severity of cucumber plants in both the systems. The yield of bacterium-treated cucumber plants was significantly higher than those of Pythium-treated or untreated control plants. In the treatment containing P. polymyxa PKB1 alone without Pythium-inoculant, the bacterium also protected the plants from opportunistic fungal infections and the cucumber plants had higher yield. The results of present study demonstrate that P. polymyxa PKB1 has a potential as a protective biocontrol agent in greenhouse cucumber industry. | |
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