The present work was carried out to study effect of adding some biocontrol agents, are used to control root rot disease in broad bean and soybean plants, on non-target beneficial microorganism. These studies were carried out under laboratory, greenhouse and field conditions to confirm correlate scientific facts with application in field.
Lab. studies showed that the most dangerous effects of Rhizoctonia solani and Sclerotium rolfsii have occurred at pre and post-emergence damping off of seedlings. All tested antagonists and their cultural filtrates at concentration 50%, at the age cultural of 10 and 3 days for antagonistic fungi and bacteria, respectively on pH 7.2 caused significant reduction in the linear growth of both R. solani and S. rolfsii. The two tested antagonists (Trichoderma harzianum and Bacillus subtilis) caused malformation and changed color in the growing hyphae of both S. rolfsii and R. solani pathogens.
Greenhouse and field studies showed that all tested antagonist-treatments “(Trichoderma harzianum, Gliocladium virens and Bacillus subtilis)”combined with the beneficial bacteria “Rhizobium or Azotobacter” at the rate of 4g/kg seeds have reduced the incidence of pre-emergence and post-emergence damping off and increased significantly the percentage of plant survivals and the total nitrogen content in both breoad bean and soybean plants compared to the control. All tested antagonists each alone or combined Azotobacter or Rhizobium when used as seed dressing at the rate of 4g/kg seeds were the most effective in increasing the populations of Azotobacter bacteria in soil, the number and weight of Rhizobium nodulation by increasing plant age and also increasing the fresh and dry weight of shoots and roots, respectively. In addition increased the yield parameters "weight of pods/plant and dry weight of 100 seeds" in both broad bean and soybean plants compared with control treatment.
Key words: Broad bean, soybean plants, biocontrol agents, beneficial bacteria, damping off and root rot diseases.
Reference:
Ahmed, M.F.A. (2005). Effect of adding some biocontrol agents on non-target microorganisms in root diseases infecting soybean and broad bean plants. M.Sc. Thesis. Faculty of Agriculture Moshtohor, Benha Univ., pp 137.