Effects of volatile compounds emitted by plant growth promoting rhizobacteria (PGPR) on the biomass of Basil plants (Ocimum basilicum L)

BOGINO, P.; GIORDANO, W.; BANCHIO, E.

Rosario, Santa Fé

Congreso; V Congreso Argentino de Microbiología General; 2008

Sociedad Argentina de Microbiología General

The study of biotic interactions mediated by chemicals is one area of knowledge that most new developments has been presented in recent years. These interactions are variable between species, as well as the effects caused; that are associated with induced or constituent metabolites in response to different stimulus. These compounds, mainly secondary metabolites produce morphological and behavioral changes in the involved organism, whether plant, animal or microorganisms. There are microorganisms with beneficial effects on the ground that may have considerable potential as biocontrol agents and/or biofertilizers; this specific group of bacteria that promote growth in plants is known as "plant growth promoting rhizobacteria" (PGPR). The application of rhizobacterias has resulted in an increase in the emergency, biomass, developing root systems and increases in crop production of commercial interest. So far, there are not recorded studies on the direct effects of volatile compounds emitted by these bacteria in aromatic and medicinal plants. In this regard, studies were conducted in double partitioned Petri dishes, where in one area were inoculated with the rhizobacteria Bacillus subtilis GB03 and in the other were placed sterile basil seeds (Ocimum basilicum); in these way, there were no physical contact between bacteria and plant. After 15 days total fresh weight, leaf surface, shoot and root dry weight, stem and root length was registered. Overall, it was noted that plants in contact with the volatile compounds emitted by the PGPR strain doubled the leaf surface regarding control plants. The total fresh weight of both the stem and root showed the same trend, reflecting the effect on the dry weight. These results suggest that the volatile compounds emitted by rhizobacterias increase production of biomass. The use of these microorganisms as biofertilizers particularly in this kind of crop would bring great benefits, since they have positive effects on plants and do not produce any detrimental ecological impact on the environment or human health.