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.

Keywords

• anthocyanins
• <i>Beta vulgaris</i> L.
• chlorophyll fluorescence
• flavonoids
• gas exchange
• halophilic rhizobacteria