Biomanagement of Fusarium solani and Rhizoctonia solani causing root rot anddamping off diseases in common bean (Phaseolus vulgaris L.) via innovativerhizobacterial formulations

摘要

A cultivation-based approach was adopted to monitor the antagonistic potential of seven biopreparates towards Fusarium solani and Rhizoctonia solani causing root rot and damping off for common bean (Phaseolus vulgarius L.). The field-grown legume plant did receive the bioformulations as seed treatment and soil drench simultaneously in presence of pathogen infestation. In the first field trial, pre-damping off of seed-treated beans averaged 19.2% against 16.8% in case of soil drench; the corresponding estimates for post-damping off were 9.4 and 7.7%. The bioproduct efficiency to restrict the pathogenicity of fungi hardly exceeded 18% with seed treatment and 31% adopting soil drench method. Among the bioformulations, Rhizo-N entrapping Bacillus subtilis was the superior (30.2%) while Bio-health WGP was the inferior (19.9%). Soil treated beans survived better than seed-soaked ones, respective survival percentages of 74.3 and 70.6 were scored. No significant differences in bean survival were attributed to bioformulation inoculum size. The pioneeric four bioproducts of the first field experiment were applied as seed together with soil treatment in pathogen-infested soil in the second field experiment. In parallel with disease reductions, the legume plant survival was the best (average of 83.4%) when Rhizo-N was introduced into bean-soil system. Bean survival percentage positively correlated (r = 0.997) with the inocula levels of biopreparates. At harvest (120 days), the tallest plants (74.4cm) were those received the bioagent Symbian-N followed by Rhizo-N (71.9cm). Untreated beans hosted 23 nodule-like structures per plant on their root system, these spontaneously produced outgrowths increased due to bioformulation application. Plants received no biopreparates yielded 1.83 kg pods plant -1, increases in bioagent-treated beans approximated 77%