Dynamics of rhizoplane bacterial communities subjected to physicochemical treatments in hydroponic crops

A highly manageable hydroponic system based on the nutrient film technique was designed to provide accurate regulation of the physicochemical and microbiological environment of roots to investigate the rhizoplane microbial dynamics of rose plants. Bacterial communities adhering to roots were subjected to pH and active free chlorine regulation, to determine up to what point they were established. PCR-single-strand conformation polymorphism (PCR-SSCP) fingerprinting showed that pH was a potentially strong stabilisation factor for root microbial communities. Active free chlorine had no quantitative effect when applied at a concentration of 0. 15 mg l(-1), but did have a selective effect on well-established bacterial communities, which were resistant to this strong physicochemical perturbation. Thus, for the control of soil-borne diseases, the established community should be investigated, to determine its prior resistance to inoculation or to manage its physicochemical environment, increasing its robustness and excluding biological perturbation. (C) 2007 Elsevier Ltd. All rights reserved.