Effect of phosphate solubilizing fluorescent pseudomonads on cadmium uptake by corn in contaminated soil

Cadmium, because of the long half a lifetime in the human and animal body and its toxicity, has great importance in agriculture. Today, plant growth-promoting rhizobacteria (PGPR) are used to increase the bioavailability and uptake of heavy metals in polluted soils. This study aimed to investigate the effectiveness of cadmium-tolerant fluorescent pseudomonads with inorganic phosphate solubilizing ability on the cadmium uptake by maize plants in contaminated soil. For this purpose, a greenhouse experiment was conducted in factorial based on a completely randomized design with four replications. Treatments were included four levels of bacteria (without bacteria (P0) and inoculation with three isolates P1, P169, P108) and four levels of time after planting (3, 6, 9, and 12 weeks). The soils were artificially spiked with cadmium (13 mg kg−1) as Cd(NO3)2. The results showed that the inoculation of maize with the selected isolates significantly increased shoot and root dry weights and shoot cadmium uptake in comparison to non-inoculated plants. The maximum shoot dry weight observed in plants inoculated with P169 and 12 weeks (31.22% more compared to non-inoculated plants). In the 12th week after planting, there was not any significant difference among P1, P108, and P169 isolates in shoot dry weights. P1 and P108 enhanced shoot dry weights by 23.81 and 22.21 percent in comparison to control, respectively. The maximum uptake of cadmium in plant shoot was found in inoculation with P169 and 12th week. In the 12th week, P169 increased cadmium uptake of the shoot by 150 percent in comparison to the control and 13.81 and 37.75 percent, compared to P1 and P108, respectively. Although all of the isolates used in the greenhouse experiment significantly increased cadmium uptake by maize plants but the effectiveness of P169 was more evident than other isolates.