Effect of soil cadmium pollution on some physiological parameters of Hyoscyamus plant in presence/absence of growth-promoting microorganisms

Plant growth promoting microorganisms enhance plant growth and yield by virtue of direct and indirect mechanisms. In this study the effects of plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) on plant height, yield, chlorophyll a, b, relative water content (RWC), carbohydrate and proline content of Hyoscyamus plant were evaluated. The soil was polluted with different concentrations of cadmium (0, 10, 30 and 100 mg kg-1 soil), and experiment was done in a factorial with randomized complete block design with three levels of microbial inoculation including fluorescent Pseudomonads as PGPR (P. putida, P. fluorescence and P. aeruginosa), fungal inoculation with Glomus species as AMF (G. mosseae, G. intraradices and G. fasciculatum) and control condition (no inoculation). The results indicated that the experiment treatments increased significantly (P≤ 0.05) plant height, shoot dry weight compared to control condition. Furthermore, as cadmium concentration raised in soil the contents of chlorophyll a, chlorophyll b, and relative water significantly decreased. However, plants inoculated with PGPR and AMF showed considerable amount of chlorophyll a, b as well as RWC. Under Cd contamination, the contents of soluble sugar and proline increased in inoculated plants in comparison to control plants. Cd addition also significantly decreased (73% compared to Cd0) mycorrhizal root colonization. It is concluded that at the presence of Cd, inoculation with PGPR and AMF could sustain and promote plant growth.