Growth and phosphate-dissolving ability of strain SL01 under different storage temperatures and calcium phosphate levels

The growth rate and phosphate-dissolving ability of phosphate-dissolving rhizobium SL01 in different calcium phosphate Ca₃(PO₄)₂2 content of substrate and storage temperatures were determined. Based on solid culture, the results indicate enhanced colony growth with increasing levels of Ca₃(PO₄)₂. Colony diameter of treatment with 8.0 g·L^?1 Ca₃(PO₄)₂ is respectively 16.9%, 27.7%, 30.1% and 32.7% higher than that of 5.0 g·L^?1, 3.0 g·L^?1, 1.0 g·L^?1 and 0.5 g·L^?1 Ca₃(PO₄)₂ treatments. At Ca₃(PO₄)₂ range of 0~8.0 g·L^?1, the phosphate-dissolving ability of the strain is not obviously different. It is therefore more suitable to use D/d (phosphate-dissolving ring diameter to colony diameter) ratio in measuring phosphate-dissolving ability of strains in solid surrounding such as soil. Bacteria liquid is best preserved under 15 ℃, followed by 4 ℃. Phosphate-dissolving ability of SL01 under different storage temperatures is -18 ℃ > -10 ℃ > 4 ℃ > 15 ℃ > 28 ℃ > 35 ℃. The order of SL01 colony diameter under different storage temperatures is 4 ℃ > 15 ℃ > -18 ℃ > 28 ℃ > -10 ℃ > 35 ℃. Order of viable bacteria amount of strain preserved for 60 d under different temperatures is 15 ℃ > 4 ℃ > 28 ℃ > -10 ℃ > 35 ℃ > -18 ℃.