Extensive use of fertilizers and pesticides led to dangerous ecological effects and therefore the biological approaches
have been widely recommended to prevent further deterioration for the environment. The current
study was conducted to explore the potentiality of using single or combined inoculations by mycorrhizae,
Bacillus subtilis and Pseudomonas fluorescence for controlling the infection of common bean plants with Sclerotium
rolfsii on one hand and as bio-fertilizers for improving plants nutritional status on the other hand. The soil of
study was mildly infected with S. rolfsii and contained high total-P content. Thus, minimal P inputs were added
to the inoculated soil in the form of rock phosphate. Activities of plant defense enzymes i.e. chitinase, peroxidase
and polyphenol oxidase were determined under the greenhouse conditions and the results obtained herein indicated
that activities of such enzymes increased significantly owing to bio-agent inoculations. In this concern,
combined treatments resulted in further significant increases over the single ones. A field study was then conducted
for two successive years and the results reveal that single inoculations increased straw and green pod
yields as well as the uptake of P and Fe by plants as compared with the non-inoculated treatment. Combined
inoculants recorded further significant increases in these parameters even when compared with the fungicide
treated plants. Generally, straw and pod yields obtained from the second growing season were significantly
higher than those attained in the first growing one. Our study confirms the success of the used bio-treatments in
minimizing soil pollution through fertilizer and/or pesticide inputs. |
