Screening for Bacterial Strains Promoting Seed Germination of Tobacco and Study of Their Growth-Promoting Characteristics

In order to screen for bacterial strains which promote seed germination, seeds of tobacco K326 were soaked with seven bacterial strains, which come from Bacillus sp., Cupriavidus sp., Pseudomonas sp. and Agrobacteria sp., and germination related indexes, including germination rate, germination potential, germination index and vigor index, were measured growth-promoting characteristics of two strains were determined. Soluble phosphorus contents were measured by molybdenum blue colorimetry. IAA contents and siderophore secreting capacity were measured by the methods of Salkowski and CAS, respectively. The results showed that germination related indexes of tobacco seeds were obviously increased after treated with two highly effective ammonifying Bacillus strains isolated from tobacco-planting soil in Guizhou. Bud length of these two treated groups was much higher than control. Phosphorus-dissolving contents of Bacillus toyonensis AMM-2 and Bacillus mobilis AMM-5 were 26.26 and 26.80 mg/L, IAA contents were 21.57 and 7.40 μg/mL, and siderosphere relative contents were 35.08% and 8.64%, respectively. So these two highly effective ammonifying Bacillus strains had good growth-promoting characteristics and significant effects on increasing seed germination of tobacco. They could be used for floating system and providing basis for developing growth-promoting organic fertilizers.