Growth and nutrient uptake of orchardgrass (Dactylis glomerata L.) and meadow fescue (Festuca pratensis Huds.) as affected by rhizobacteria

Abstract

A diverse group of soil bacteria found in the rhizosphere which can colonize plant roots and improve plant growth are designated as plant growth promoting rhizobacteria. The aim of this study was isolation and screening of different rhizobacterial strains for plant growth promoting characteristics and their ability to improve growth of two grass species, orchardgrass (Dactylis glomerata L.) and meadow fescue (Festuca pratensis Huds.). The strains investigated, belonging to the genera Azotobacter, Bacillus, Pseudomonas and rhizobial bacteria, showed various plant growth promoting traits, such as phosphate solubilisation, siderophore production, and indole-3-acetic acid (IAA) production. Co-inoculation of meadow fescue with Azotobacter chroococcum A2 and Sinorhizobium meliloti or Pseudomonas sp., and A. chroococcum A5 with S. meliloti, significantly increased shoot dry weight (SDW)(25-33%), as well as total N (26-33%), P (24-31%) and K (26-28%) contents in plants (mg pot-1), compared to uninoculated control. In addition, inoculation of orchardgrass with A. chroococcum strain A1, as well as co-inoculation with B. megaterium and A. chroococcum A1 or A31, significantly increased SDW (51-59%) and total N (54-59%), P (51-74%) and K (49-55%) contents, compared to uninoculated control. Nitrogen percentage in SDW was slightly higher than sufficiency ranges, while K percentage was optimal in all treatments in both species. Phosphorous percentage was lower than sufficiency ranges as a consequence of very low soil P content. The results emphasize the potential of particular rhizobacteria to improve the growth of forage grasses.