Table 1. Examples of PGPB used as inoculants or bacterial culture of different plant species in soil experiments.
| Plant | Experimental conditions | Microorganism (s) | Main PGP-traits3 | Main results | References |
|---|---|---|---|---|---|
| Chickpea1 | Field: liquid culture applied to seed | Pseudomonas jessenii PS06, Mesorhizobium ciceri C-2/2 | N2-fixing (C-2/2), P-solubilizing (PS06) | Plants inoculated with C-2/2, in single or dual inoculation, produced higher nodule fresh weight, nodule number and shoot N content, while PS06 had no significant effect on plant growth. However, the co-inoculation ranked highest in seed yield and nodule fresh weight. | Valverde et al. (2006) |
| Pot and field: liquid culture applied to seed | Rhizobium spp., B. subtilis OSU-142, Bacillus megaterium M-3 | N2-fixing (Rhizobium, OSU-142), biocontrol activity (OSU-142, M-3), P-solubilizing (M-3) | In the field, all the combined treatments containing Rhizobium were better for nodulation than the use of Rhizobium alone. Nodulation by native Rhizobium population was increased in single and dual inoculations with OSU-142 and M-3. | Elkoca et al. (2008) | |
| Maize | Pot: liquid culture applied to seed or soil | Burkholderia ambifaria MCI 7 | Siderophore, antifungal activity | The inoculation method influenced the plant growth: seed-applied liquid culture promoted increase on shoot fresh weight as the control, while soil-applied liquid culture reduced plant growth markedly. | Ciccillo et al. (2002) |
| Pot: liquid culture applied to seed | Pseudomonas alcaligenes PsA15, Bacillus polymyxa BcP26, Mycobacterium phlei MbP18 | N2-fixing, antifungal activity (BcP26 and MbP18), IAA (PsA15 and MbP18) | Bacterial inoculation had a much better stimulatory effect on plant growth and NPK content in nutrient-deficient soil than in nutrient-rich soil, where the bacterial inoculants stimulated only root growth and N, K uptake of the roots. | Egamberdiyeva (2007) | |
| Pot and field: liquid inoculant applied to seed | A. brasilense Ab-V5 | N2-fixing, IAA | In pot trials with clay soil, plant growth was increased when Ab-V5 was applied at full dose. In sandy soil, nutrients and Ab-V5 were needed for a significant increase in the maize response. In the field, the grain production was increased when Ab-V5 and N were added, compared to N fertilization alone. | Ferreira et al. (2013) | |
| Pea | Field: peat powder, granular, and liquid inoculant applied to seed or soil | Rhizobium leguminosarum bv. viciae | N2-fixing | The effects of inoculant formulation on nodule number, N accumulation and N2-fixation were: granular peat powder liquid = uninoculated. Soil-applied inoculant improved N nutrition of field pea compared to seed-applied inoculation, with or without applied urea-N. | Clayton et al. (2004) |
| Pot: liquid culture applied to seed | P. fluorescens ACC-5 (biotype G) and ACC-14, P. putida Q-7 (biotype A) | ACC-deaminase | Rhizobacteria containing ACC-deaminase significantly decreased the “drought stress-imposed effects”, although with variable efficacy at different moisture levels. Strain ACC-5 greatly improved the water use efficiency at lowest soil moisture level. | Zahir et al. (2008) | |
| Peanut2 | Pot and field: liquid culture applied to seed | P. fluorescens PGPR1, PGPR2, and PGPR4 | ACC-deaminase, IAA, siderophore, antifungal activity | Pod yield and NP contents in soil, shoot and kernel were significantly enhanced in treatments inoculated in pots, during rainy and post-rainy seasons. The PGPRs also significantly enhanced pod yield, haulm yield and nodule dry weight compared to controls, in 3 years of field trials. | Dey et al. (2004) |
| Rice | Field: peat inoculant applied to soil and seedling | Pseudomonas spp., B. amyloliquefaciens, B. subtilis,soil yeast | Not described | Inoculation significantly increased grain and straw yields and total N uptake, as well as grain quality in terms of N percentage. Inoculation was able to save 43 kg N ha−1, with an additional rice yield of 270 kg ha−1 in two consecutive rainy seasons at the experimental site. | Cong et al. (2009) |
| Pot and field: liquid culture applied to seedling | Azospirillum sp. B510 | N2-fixing, IAA | The field experiment indicated that inoculation with B510 increases tiller number, resulting in an increase in seed yield at commercial levels when compared with uninoculated plants. | Isawa et al. (2010) | |
| Field: liquid culture applied to seedling | Azospirillum sp. B510 | N2-fixing, IAA | Growth in terms of tiller numbers and shoot length was significantly increased by inoculation. The application of Azospirillum sp. B510 not only enhanced rice growth, but also affected minor rice-associated bacteria. | Bao et al. (2013) | |
| Soybean | Field: granular and peat inoculant applied to seed and in-furrow | Bacillus cereus UW85 (granular) and B. japonicum (peat) | Not described | The inoculation with UW85 resulted in stimulations in shoot dry weight, increased seed yield and seed N content, but the effect was site-specific. The stimulation in growth and N parameters by UW85 treatment was proportionally greater in the absence of B. japonicum inoculation than in the presence of the rhizobial inoculant. | Bullied et al. (2002) |
| Field: liquid inoculant applied to seed and in-furrow | B. japonicum SEMIA 5079 and SEMIA 5080, A. brasilense Ab-V5 and Ab-V6 | N2-fixing, IAA | Inoculation of seeds with rhizobia increased soybean yield by 8.4 %, and co-inoculation with A. brasilense in-furrow by an average 16.1 %. Seed co-inoculation with both microorganisms resulted in a mean yield increase of 14.1 % in soybean compared to the uninoculated control. | Hungria et al. (2013) | |
| Pot: liquid culture applied to seed | B. amyloliquefaciens sks_bnj_1 | Siderophore, IAA, ACC-deaminase, antifungal activity, phytases | Inoculation significantly increased rhizosphere soil properties (enzyme activities, IAA production, microbial respiration, microbial biomass-C), and nutrient content in straw and seeds of soybean compared to uninoculated control. | Sharma et al. (2013) | |
| Sugarcane | Pot and field: liquid culture applied to seedlings | B. vietnamiensis MG43, G. diazotrophicus LMG7603, H. seropedicae LMG6513 | N2-fixing | Biomass increase due to MG43 inoculation reached 20% in the field. The inoculation of three strains was less effective than inoculation by a single MG43 suspension. | Govindarajan et al. (2006) |
| Field: liquid culture applied to stem cuttings | G. diazotrophicus VI27 | N2-fixing, siderophore, IAA, P-solubilizing | The strain showed a significant increase in the number of sets germinated, in the amount of soluble solids, and in the yield of sugarcane juice compared to control. | Beneduzi et al. (2013) | |
| Wheat | Field: liquid inoculant applied to seed | A. brasilense INTA Az-39 | N2-fixing, IAA | The inoculated crops exhibited more vigorous vegetative growth, with both greater shoot and root dry matter accumulation. Positive responses were found in about 70% of the experimental sites (total: 297 sites), independently of fertilization and other crop and soil management practices. | Díaz-Zorita and Fernández-Canigia (2009) |
| Pot: liquid culture applied to soil | B. subtilis SU47, Arthrobacter sp. SU18 | IAA, P-solubilizing | Sodium content was reduced under co-inoculation conditions but not after single inoculation with either strain or in the control. Plants grown under different salinity regimes and PGPR co-inoculation showed an increase in dry biomass, total soluble sugars and proline content, and reduced activity of antioxidant enzymes. | Upadhyay et al. (2012) | |
| Wheat and maize | Field: peat and liquid inoculant applied to seed | A. brasilense Ab-V5 and Ab-V6 | N2-fixing, IAA | Inoculants increased maize and wheat yields at low N fertilizer starter at sowing by 27% and 31%, respectively. A liquid inoculant containing a combination of the strains proved to be as effective as peat inoculant carrying the same strains, in both maize and wheat. | Hungria et al. (2010) |
1
Cicer arietinum L.
2
Arachis hypogaea L.
3
When the characteristic is not displayed by all strains, those that present it are shown in parenthesis.