Abstract: Phosphate-solubilizing bacteria are important for agriculture,especially for legume plants,because they increase the available phosphorus in soils and improve the nodulation and nitrogen fixation of rhizobia.In the present paper,phosphate-solubilizing bacteria in the rhizosphere of red clover(Trifolium pratense L.)were screened based on PKO culture medium and molybdenum blue method.Total 21 strains were obtained,among which,10 strains had the ability to solubilize inorganic phosphate,the ratio of D/d(diameter of phosphate-dissolving zone / diameter of bacterial clone)varied from 1.13 to 1.62.And there were 5 strains had the ability to solubilize organic phosphate on Mengjinna organic culture medium,the ratio of D/d changed from 1.07 to 1.83.Strains lhs3,lhs11,and lhs15 could solubilize both inorganic phosphate and organic phosphate.In liquid culture,the available phosphate increment by inorganic phosphate-solubilizing bacteria changed from 5.0 mg/L to 596.3 mg/L and organic phosphate-solubilizing bacteria-0.03 mg/L to 58.34 mg/L using molybdenum blue method.Strains lhs6 and lhs8 had significantly higher ability in inorganic phosphate-solubilizing than other strains and strain lhs11 had the highest ability in organic phosphate dissolving.The ability of phosphate dissolving by bacteria was correlated to pH and organic acid,but not significantly.Strains lhs6,lhs8,and lhs11 showed great potential for agricultural use in microbiological fertilizer and deserved further study.

Key words: Rhizosphere, Phosphate-solubilizing bacteria, Phosphate solubilizing ability, Trifolium pratense L.

摘要： 利用PKO培养基从兰州地区红三叶(Trifolium pratense L.)根际分离、筛选出21株菌株,其中10株具有溶解无机磷能力,其D/d值(溶磷圈直径与菌落直径比值)在1.13-1.62之间;5株在蒙金娜有机磷培养基上形成明显透明圈,其D/d值在1.07-1.83之间;3株菌株既能溶解有机磷又可溶解无机磷。对其中D/d值较高的6株溶解无机磷菌株和5株溶解有机磷菌株进行液体培养,用钼蓝比色法测定有效磷增量分别为5.0-596.3和-0.03-58.34 mg/L。lhs6和lhs8溶解无机磷能力较其他菌株强,lhs11溶解有机磷能力较其他菌株强。菌株中lhs6、lhs8和lhs11在后续微生物菌肥研制中具有较大潜力。

关键词: 根际, 溶磷菌, 溶磷能力, 红三叶