Consortia of Plant-Growth-Promoting Rhizobacteria Isolated from Halophytes Improve the Response of Swiss Chard to Soil Salinization

Abstract

Inadequate fertilization or the indiscriminate use of water with high salt concentrations have led to salinization of agricultural soils. In this context, biofertilization with plant-growth-promoting rhizobacteria (PGPR) is an environmentally benign strategy to stimulate plant growth, even under salt stress. Thus, we studied the use of isolated PGPR consortia from halophytes to enhance Swiss chard growth under saline conditions. Growth, photosynthetic apparatus response, nutrient status, pigment concentrations, and secondary metabolites with antioxidant activity were determined in Swiss chard plants grown at 0 and 85 mmol L−1 NaCl. In general, inoculation of plants with PGPR has been shown to be an effective strategy to stimulate the growth of Swiss chard and improve its tolerance to salt stress. Inoculated plants watered with 85 mmol L−1 NaCl showed higher values of leaf dry weight than control plants. Furthermore, PGPR inoculation reduced electrolyte leakage and Na+ uptake and improved chlorophyll a fluorescence parameters, chlorophyll and carotenoid concentrations, stomatal conductance, and antioxidant capacity of Swiss chard. Finally, our findings highlight the potential of isolated PGPR from halophytes to counterbalance the deleterious effect of salinity and stimulate crop growth.

Biofertilization with PGP Bacteria Improve Strawberry Plant Performance under Sub-Optimum Phosphorus Fertilization

“…Finally, it should be noted that other consortium strains, such as SMT38 and S110, have the capacity to produce ACC, which is capable of reducing the plant ethylene level [21], helping to overcome the potential growth inhibition induced by environmental stress factors [17,18,50], and therefore, preventing the level of ethylene from becoming growth inhibitory [65], which would allow greater development of the above-ground and belowground biomasses, which we were able to verify in our experiment.…”

“…The strains were named: Variovorax paradoxus (S110), Pseudomonas sp. (SDT3), Bacillus velezensis (SMT38), Pseudarthrobacter oxydans (SRT15), and Bacillus zhangzhouensis (HPJ40); for the isolation, characterization, identification, and conservation details, see our previous studies [18,[31][32][33][34]. Bacterial strains were selected because they had growth self-compatibility and exhibited high multi-stress resistance and a variety of complementary plant growth-promoting (PGP) properties, aspects that make them an ideal inoculum to be adapted to and employed in several agronomic management contexts and environmental conditions, thus being able to improve fertilization process efficiency in strawberry crops.…”

“…Bacterial strains were selected because they had growth self-compatibility and exhibited high multi-stress resistance and a variety of complementary plant growth-promoting (PGP) properties, aspects that make them an ideal inoculum to be adapted to and employed in several agronomic management contexts and environmental conditions, thus being able to improve fertilization process efficiency in strawberry crops. Table 1 shows the PGP properties that were analyzed in several of our previous studies [18,[31][32][33][34]. For the inoculum preparation technical details, see Navarro-Torre et al [35] and Flores-Duarte et al [36]…”

“…However, despite this progress, strawberry cultivation still uses a large number of agrochemicals, which contribute to maintaining high production levels but entail high economic costs for producers, not to mention the aforementioned obvious environmental risk. In this way, positive rhizospheric interactions due to microbiota naturally present in the soil or supplied in the form of biofertilizers positively affect soil quality [13][14][15] and can be exploited as an alternative to agrochemicals to improve crop yield and reduce chemical input [16][17][18].…”

Bioaugmentation Improves Phytoprotection in <em>Halimione Portulacoides </em>Exposed to Mild Salt Stress: Perspectives for Salinized Soil Restoration

“…Effective PGPR usage is constrained by a number of variables such as climate, water, soil characteristics, target species, etc. [24], and it is understood that these bacteria have growth conditions where they can be more or less effective, for example, it was found that some PGPR with increasing salinity, and with no relation with bacterial death, did not display their plant-growth promoting attributes [25]. Nonetheless, several studies have not only identified salt tolerate PGPR but also associated PGPR consortia specific for salt-stressed plants [21,23].…”