Antagonistic Effect of Plant Growth Promoting Rhizobacteria (PGPR ) as Biocontrol of Plants Damping-Off.

Abstract

In the rhizosphere can be found that different groups of plant growth promoting rhizobacteria (PGPR). These bacteria including variety genera of nitrogen fixation and potassium silicate minerals solubilization in soils which can promote the growth of plant. In the present work, nine cotton and sugar beet rhizospheric soil samples were collected from two governorates in Egypt.Twenty three bacteria were isolated and screening for antagonism to soil borne fungi i.e.,Fusarium oxysporum and growth on potassium- silicate medium, indole acetic acid (IAA) , ammonia productions , cyanid hydrogen (HCN),catalase as biofertilizers and bioagents to soil borne fungi. Four bacterial isolates showed highly antagonistic effects for pathogenic fungus (F.oxysporum) and three of them were positive for growth on potassium-silicat medium . IAA production was shown by all the bacterial isolates. Three isolates were positive for ammonia production. Two isolates were positive for HCN production and all isolates were found to be catalase positive. These bacterial isolates as maximum antagonistic for pathogen and growth promotion for plants were identified on the basis colonies morphology on silicate medium, Gram staining , spore formation , capsule forms and biochemical tests as Bacillus spp. (B.subtilis, B.amyloliquefaciens, B.weihensteephanensis and B.pseudomycodies). As PGPR and bioagents are environmental friendly to increase production of crops and health. Therefore, these isolates can be utilized for biofertilizer and biological control under agroclimatic conditions of Egypt.