Siderophore and ACC Deaminase Producing Bacteria Enhance the Growth of Vigna spp Under Iron Limited Saline Soils

The present study aimed on siderophore and ACC deaminase producing bacteria to mitigate salinity stress and simultaneous mobilization of nutrients. In this study, eight siderophore and ACCD producing bacterial strains selected from a previous study showed that four strains (CWTS 5, CWTS 10, KSBTS 12 and SBTS 12) enhanced mung bean and black gram plant growth in the plate assay (200 mM NaCl stress). Furthermore, evaluation in pot studies (10 g kg^− 1 NaCl stress) revealed enhanced root (170.05-237.96% and 16.83-95.74%) and shoot length (139.91-196.96% and 19.87-77.26%) of mung bean and black gram, respectively, compared to the control. Inoculated plants also enhanced the uptake of nitrogen (36.62–41.47 mg g^− 1 and 36.19–47.23 mg g^− 1), phosphorous (3.29–3.98 mg g^− 1 and 3.15–4.21 mg g^− 1), Fe (44.36–56.21 µg g^− 1 and 41.02–44.31 µg g^− 1), Na⁺ ions (40.65–45.35 µg g^− 1 and 20.18–22.11 µg g^− 1), and chlorophyll content (12.71–29.33 mg g^− 1 and 10.55–26.39 mg g^− 1) of mung bean and black gram plants. The Cl⁻ ion uptake by mung bean and black gram plants was below the toxic limit of 94.62–116.6 µg g^− 1 and 117.6-150.2 µg g^− 1 respectively. The inoculation of bacterial strains also increased the siderophore (259.53-556.05% and 267.26-304.77%) and ACCD (3.02–5.05 µmol mL^− 1 and 2.84–4.41 µmol mL^− 1) production in the soil and the enhancement was directly correlated with N, P, Fe and chlorophyll content of both the plants. In addition, the inoculated bacteria also enhanced the soil respiration activity such as dehydrogenase enzyme (112.53–167.40 µg g^− 1 and 88.92-181.28 µg g^− 1), FDA hydrolysis (31.66–44.51 µg g^− 1 and 16.94–38.20 µg g^− 1) and alkaline phosphatase enzyme (691.53–851.53 µg g^− 1 and 511.53-811.53 µg g^− 1) of mung bean and black gram soils. Overall, strains CWTS 5 (Bacillus subtilis), SBTS 12 (Rhodococcus sp.), and CWTS 10 (Bacillus albus) can be used to mitigate NaCl stress and mobilize nutrients and Fe in plants.