The role of four bioagents, i.e. Bacillus subtilis, Pseudomonas fluorescens, Saccharomyces cerevisiae and Trichoderma viride in controlling damping-off disease of bean (Phaseolus vulgaris L.) caused by Sclerotium rolfsii was evaluated under greenhouse and field conditions. Greenhouse experiment indicated that all the tested bioagents significantly reduced the incidence of the disease compared with control treatment. In addition, the most effective treatments were B. subtilis, T. viride and P. fluorescence, which reduced disease incidence more than 83.7 and 74.5% for pre- and post-emergence damping-off, respectively and increased the survived plants to 90.3, 86.1 and 87.6%, respectively compared with 26.3% in untreated plants. Also, they significantly increased dry and fresh weight of bean shoot & root as well as resulted in considerable increase to the activity of peroxidase, polyphenol oxidase and chitinase activity more than 260.0, 109.0 and 218.3%, respectively. Under field conditions during 2009 and 2010 growing seasons, data revealed, also, that all the tested bioagents significantly reduced disease incidence with considerable increase to the survived plants and the produced seed yield compared with control treatment. As for the first season, the most effective treatments were B. subtilis, T. viride, S. cerevisiae and P. fluorescens, which reduced disease incidence more than 61.3 and 41.3% than the control for pre- and post-emergence damping-off, respectively. The corresponding percentages of survived plants were 78.2, 79.0, 75.2 and 76.8%, respectively viz. 38.5% for the control. On the other hand, the most effective treatments for increasing seed yield was S. serivisae followed by P. fluorescens, being 894.95 and 748.1 kg/feddan viz. 269.2 kg/feddan for the control. The other two bioagents showed moderate effect. The same trend was obtained during the second season. It could be suggested that such bioagents might be promising as alternatives to control bean damping-off caused by S. rolfsii.
Keyword: Bean, bioagents, enzymes, fresh and dry weight, Sclerotium rolfsii, seed yield. |
