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Suppression of root  diseases and enhancement of  VA mycorrhizal population in  sunflower and tomato  by the mycorrhizospheric fluorescent Pseudomonas  
S. EHTESHAMUL-HAQUE (1), S. S. Bokhari (2), S. A. Ali (3), V. Sultana (4), J. Ara (5). (1) Department of Botany, University of Karachi, Karachi, Pakistan; (2) Department of Botany, University of Karachi, Karachi, Pakistan; (3) HEJ Research Institute of Chemistry, University of Karachi, Karachi, Pakistan; (4) Department of Biochemistry, Univ

The vesicular arbuscular mycorrhizal (VAM) fungi, are obligate symbionts, improved  uptake of nutrients by plants especially   phosphorus. Several investigations  have indicated that  mycorrhizosphere bacteria may affect  VAM fungi and their host plant. In this study, efficacy of some isolates of mycorrhizospheric fluorescent  <i>Pseudomonas </i>  (MRFP) that have shown significant activity against root rotting fungi (<i>Macrophomina phaseolina, Rhizoctonia solani, Fusarium solani, F.oxysporum</i>) and root knot nematode (<i>Meloidogyne javanica</i>)<i> in vitro  </i>was evaluated in pots and in field plot experiments using sunflower and tomato as test  plants. Most of the test MRFP showed significant biocontrol potential against soilborne pathogens  by reducing the infection of root rotting  fungi and gall formation by  root knot nematode. The application of mycorrhizospheric fluorescent <i>Pseudomonas </i>significantly increased VAM population  around the roots and   in most of the cases  showed better uptake of phosphorus by the plants.  However, mixed application of  VAM and fluorescent <i>Pseudomonas </i>did not show any added advantage. MRFP caused pronounced effect on sunflower by producing taller  plants with greater fresh shoot weight both in screen house and field plot experiments.  Fruit weight of tomato and flower weight of sunflower  were also found significantly  higher in most of the bacterized treatments as  compared to control plants. .

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