Synergistic effect of beneficial rhizosphere microflora in biocontrol and plant growth promotion.

Biological systems are getting more relevance than chemical control of plant pathogens as they are not only eco-friendly and economic in approach but are also involved in improving the soil consistency and maintenance of natural soil flora. Plant growth promoting rhizosphere microorganisms were isolated from three different tree rhizospheres using selective culture media. Five microorganisms were selected from each rhizosphere soil based on their efficiency and screened for their ability to promote plant growth as a consortium. Each of the developed consortium has a phosphate solubilizer, nitrogen fixer, growth hormone producer, heterotrophic member and an antagonist. The plant growth promoting ability of the microbial members present in the consortium was observed by estimating the IAA production level and also by the nitrogenase activity of the nitrogen fixers. The biocontrol potentiality of the consortium and the antagonist present in the consortium were checked by both dual plate assay and cross-streaking technique. Consortial treatments effected very good growth promotion in Lycopersicon esculentum Mill and the treated plants also developed resistance against wilt pathogen, Fusarium oxysporum f. sp. lycopersici though the effect was well pronounced with consortium developed from Santalum album. ((c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).