Physiological Mechanism of Salt Tolerance in Maize as Affected by Rhizobacteria of Maize Rhizosphere and the Bacteria from Produced Water

The present study was aimed to evaluate the role of Bacillus thuringiensis and Cytobacillus oceanisediminis isolated from rhizosphere of maize irrigated with 90% diluted high total dissolved solid (TDS) bearing produced water. Two other bacteria Ralstonia picketti and Brevibacillus invocatus were isolated from produced water alone and in combination with salicylic acid (SA). Inoculation effects of these isolates were studied on growth and physiology of maize cv. Kashmir gold irrigated with produced water having electrical conductivity (EC) and TDS greater than sea water. The control plants were irrigated with 90% diluted TDS water supplemented with 5 mL LB media. The inoculated plants were irrigated with 90% diluted TDS water supplemented with 5 mL LB broth of inoculum of respective bacterium. After one week, 10–5 M solution of salicylic acid (SA) was sprayed. The EC, TDS and COD (chemical oxygen demand) of produced water were determined. Growth parameters viz. root/shoot fresh and dry weight, shoot/root length and shoot/root dry weight ratio were also increased in plants inoculated with B. thuringiensis and significant increases in protein, proline, sugar, flavonoids, phenolics, chlorophyll (a and b), carotenoids, superoxide dismutase, peroxidase and catalase in inoculated plants was observed. Combined treatment of isolated bacteria with SA, B. thuringiensis (BT + SA) and C. oceanisediminis (CO + SA) were more effective than R. picketti (RP + SA) and B. invocatus (BI + SA). The BT + SA increased soil organic matter and essential nutrients Ca, Mg, K and P significantly concomitant with significant decrease in the COD and BOD (biological oxygen demand) value of produced water over control is noteworthy for successive plantation.