Role of growth promoting substances producing microorganisms on tomato plant and control of some root rot fungi
Abstract: A number of 261 bacterial isolates were obtained from different plants rhizosphere. High percentage of these isolates produced indole acetic acid (IAA), siderophores and hydrogen cyanide. Only 31 isolates in-vitro antagonized R. solani or F. solani, the causative agents of tomato root rot, but varied greatly in their in-vivo antagonistic activities and effects on shoot and root dry weights. Most efficient four isolates against R. solani and F. solani had also the potential to produce considerable amounts of IAA, gibberellins, siderophores and hydrogen cyanide. These isolates were identified as strains of Bacillus subtilis (three strains 47, 82 and 104) and Pseudomonas synxantha (one strain 95).
Optimization of carbon, nitrogen sources, aeration and incubation period for mass production by selected strains were studied. Highest growth yield for B. subtilis 47, 82, 104 strains was obtained when grown on King’s medium (containing glycerol and peptone), supplemented with 0.1 g/L tryptophan, at 30 ºC for 72 h, initial pH 7.2 and shaking speed 150 rpm. The same growth conditions favoured highest mass production by Ps. synxantha 95 except that peptone of the medium was replaced by yeast extract.
In a pot experiment, inoculation with selected strains- in soil infested with root rot fungi- antagonized R. solani and F. solani and promoted tomato growth and fruit yield. Such beneficial effect was more pronounced by repeated inoculation up to four times. These treatments favoured highest survival rates, greater proliferation of rhizosphere microflora, higher dehydrogenase activity in the rhizosphere, and considerable enhance in nutrients (NPK) uptake. It is recommended to use these strains as a common biocontrol practice in agriculture.
Publication year 2005
Organization Name
Country Egypt
Department Agricultural Microbiology Research
Author(s) from ARC
Agris Categories Seed production and processing
AGROVOC
TERMS		 Auxins. Gibberellic acid.
Proposed Agrovoc Plant growth promoting rhizoba;biocontrol agent;root rot fungi;indole acetic acid;B. subtilis;Psuedomonas synxantha;
Publication Type PhD Thesis
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