## 4 Discussion
The EPS produced by bacterial strains help in binding the soil particles, improves soil structure, increase moisture retention capacity of soil and help in biofilm formation by the bacterial strains [68]. The PGPR increase crop tolerance to Cd-stress due to production of exopolysaccharides, siderophores, and plant hormones along with other PGP traits [69; 70]. The PGPR strains used in our study also have potential to solubilize inorganic phosphate along with IAA and EPS production ability that might have helped them to proliferate more in the root zone that enhanced their colonization. The solubilization of phosphate in turn enhanced their survival efficacy under stress [71] subsequently helping in plant growth promotion. [PERSON] et al. [72] reported that the rhizobacterial strain _Ralstonia mannitololytica_ KUCd7 effectively removed Cd from Cd-amended media, solubilized inorganic phosphate, and produced siderophores in addition to 1-aminocyclopropane-1-carboxylic acid (ACC)-deaminase activity. They also observed that the inoculation of _Brassica juncea_ L. with this bacterium improved plant growth through reduction in Cd-uptake. In our study, inoculation with Cd-tolerant, IAA-producing rhizobacterial strains reduced the negative effects of Cd-stress on physiological parameters thus improved the SPAD value and RWC of _Brassica juncea_ (L.) plants under Cd-stress over control. The improvement in plant physiology under Cd-stress might be due to EPS and IAA production ability of these strains. Similarly, [PERSON] et al. [71] reported the improvement in SPAD value and relative water content due to inoculation with PGPR strains having the ability to produce IAA along with ACC-deaminase activity [73]. Several other PGP traits of bacterial strains are also involved in improving the growth and physiology of inoculated plants [74; 75]. Improvement in RWC of plants is a good indicator of reliving stressed conditions. Inoculated plants showed more RWC because these strains increased the size of the root system by initiating secondary roots. Solubilization of phosphate by these strains might also have helped generate more root proliferation [70] thus enabling plants to explore more soil for water and nutrients. The SPAD value represents the chlorophyll value that is a way of non-destructive leaf chlorophyll contents measurements that correlated the crop nitrogen status to chlorophyll contents. In previous studies, increase in chlorophyll contents after inoculation with PGPR under Cd-stress has been reported [76]. Increased chlorophyll content due to inoculation might happen as a result of enhanced Mg\({}^{2+}\) that accelerated the production of photosynthates [76]. The increase in chlorophyll content is also correlated to improvement in nutrient uptake by crop plants due to phosphate solubilization, siderophores production and IAA production by inoculated strains [77; 78]. Plants use several adjustments under stressed environments to cope with negative effects of these stresses. Production of proline under stress is one of those adjustments [71]. Accumulation of proline and other organic metabolites occurs in plants for osmotic adjustment under stress [79]. Production of higher levels of proline by crop plants under Cd-stress has been reported [29; 80]. The higher concentration of proline under acts to adjust intercellular osmotic potential in crop plants [81] that requires additional metabolic energy. This additional energy is met by shifting the normal metabolic processes and thus plants experience stressed conditions [82]. In our study, inoculation with Cd-tolerant, IAA-producing rhizobacterial strains having the potential of EPS production decrease the production of proline that might be due to reduction in negative effects of Cd-stress due to IAA, EPS and siderophores production by these strains. These results are supported by the previous work conducted by several scientists under stressed conditions [29; 31; 71; 83; 84].