Beneficial microorganisms in growth promotion and stress tolerance in petunia plugs

Abstract

Petunia is a specie usually propagated by plugs, being used commercially in pots and flowerbeds, presenting variety of colors and abundant flowering. To improve plugs production, the use of plant growth promoting bacteria (PGPR) can improve growth and resistance to plants. With this purpose, we highlight the bacteria of genus Pseudomonas spp., specially the auxin and ACC deaminase producers for growth promotion and reducing stress symptoms caused by ethylene. Thus, the objective was to identify and evaluate the use of strains of Pseudomonas spp. in growth promotion and water stress in petunias plugs. Strains of Pseudomonas spp. were selected for the detection of ACC deaminase activity, identification of the best application time and effect of the application of these bacteria in growth promotion and resistance under water stress conditions. Greater activity of ACC deaminase was observed for P. putida UW4 +, P. poae 29G9 and P. brassicacearum Delaware. The spraying of the solutions containing these bacteria applied at sowing and third day after sowing promoted greater development of shoots and root system of the plugs. Among the studied strains, no resistance promoting effect was observed for plants submitted to stress in plugs stage. However, the use of Pseudomonas strains contributed to the development of plugs, accelerating flowering and producing more flowers in plants that were not submitted to stress in the plugs stage.