Alfalfa growth promotion by bacteria grown under iron limiting conditions

This investigation has been conducted to compare and contrast, the impact of 18 potentially plant growth-promoting bacterial strains, cultured in rich and iron-deficient minimal media, on alfalfa seed germination and seedling vigor. Our results showed that,seed germination was improved by all of the bacterial strains grown in iron-deficient minimal medium. We also found that all the seeds inoculated with the bacterial strains grown in iron-deficient minimal medium produced seedlings with larger roots (55-66 mm) than the roots of uninoculated control plants (54.9 mm). Furthermore, most of the strains cultivated in iron-deficient minimal medium generated seedlings with larger roots than those seeds inoculated with microbial cells grown in iron-rich medium (37-59 mm). Overall, seeds inoculated with the strain U cultivated in iron-deficient minimal medium gave rise to plantlets, with the greatest length (81 mm). On the other hand, seeds inoculated with bacterial cells grown under iron-rich media show significantly higher stem and root dry weight, which is an indication of the influence of the growth conditions on the plant growth-promoting ability of these microorganisms. (C) 2002 Elsevier Science Ltd. All rights reserved.