Application of Endophytic Pseudomonas fluorescens and a Bacterial Consortium to Brassica napus Can Increase Plant Height and Biomass under Greenhouse and Field Conditions

Abstract

Plant associated bacteria with plant growth promotion (PGP) properties have been proposed for use as environmentally friendly biofertilizers for sustainable agriculture; however, analysis of their efficacy in the field is often limited. In this study, greenhouse and field trials were carried out using individual endophytic Pseudomonas fluorescens strains, the well characterized rhizospheric P. fluorescens F113 and an endophytic microbial consortium of 10 different strains. These bacteria had been previously characterized with respect to their PGP properties in vitro and had been shown to harbor a range of traits associated with PGP including siderophore production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and inorganic phosphate solubilization. In greenhouse experiments individual strains tagged with gfp and Kmr were applied to Brassica napus as a seed coat and were shown to effectively colonize the rhizosphere and root of B. napus and in addition they demonstrated a significant increase in plant biomass compared with the non-inoculated control. In the field experiment, the bacteria (individual and consortium) were spray inoculated to winter oilseed rape B. napus var. Compass which was grown under standard North Western European agronomic conditions. Analysis of the data provides evidence that the application of the live bacterial biofertilizers can enhance aspects of crop development in B. napus at field scale. The field data demonstrated statistically significant increases in crop height, stem/leaf, and pod biomass, particularly, in the case of the consortium inoculated treatment. However, although seed and oil yield were increased in the field in response to inoculation, these data were not statistically significant under the experimental conditions tested. Future field trials will investigate the effectiveness of the inoculants under different agronomic conditions.

Efficient colonization of the endophytes Herbaspirillum huttiense RCA24 and Enterobacter cloacae RCA25 influences the physiological parameters of Oryza sativa L. cv. Baldo rice

“…In recent years, a large deal of literature has been produced on co‐inoculation (consortium) of agriculturally beneficial microorganisms and in many cases benefits have been observed compared with the single inoculation (Akintokun and Taiwo, ; Sahu et al ., ; Molina‐Romero et al ., ; Lally et al ., ; Orozco‐Mosqueda et al ., ; Sahu et al ., ). The present study shows that the beneficial endophytes E. cloacae RCA25 and H. huttiense RCA24 can be promising strains to improve, directly or indirectly, nitrogen fixation in rice plants under greenhouse conditions.…”

Metabolic manipulation by Pseudomonas fluorescens: a powerful stratagem against oxidative and metal stress

“…It produces a soluble green pigment, pyoverdine responsible for its fluorescence. The microbe has the ability to grow in diverse environments, utilizes a wide range of carbon sources, tolerates disparate temperatures and proliferates in pH ranging from 4 to 8 [18][19][20]. These characteristics have been tailored naturally in order to render P. fluorescens suitable for bioremediation, in pathogen control and as biofertilizers.…”

Is the Application of Plant Probiotic Bacterial Consortia Always Beneficial for Plants? Exploring Synergies between Rhizobial and Non-Rhizobial Bacteria and Their Effects on Agro-Economically Valuable Crops

“…For instance, Camacho et al [119] showed that a Bacillus strain, considered a proper PGPR, was beneficial in the R. tropici-Phaseolus vulgaris symbiosis, but had deleterious effects when interacting with the B. japonicum-Glycine max relationship. Table 1 also shows some other examples in which the effects on plant growth and yield derived from inoculation of PPB consortia in field tests were not always beneficial or did not produce significant increases of yield or quality [87,88,[110][111][112][113][114][115]. These negative findings might be due to the enormous variety of factors affecting crops, especially in the field, where microbiomes and plants are subjected to biotic and abiotic stresses.…”