中文摘要：

以改良的PVK培养基从玉米和象草根系及其根际土壤中筛选溶磷菌，通过其在NBRIP液体培养基中水溶性磷浓度确定菌株溶磷能力的基础上，进一步利用限菌砂培试验测定菌株在玉米根际的定殖能力，并通过盆栽试验评判该筛菌方法。结果表明：NBRIP液体摇瓶试验中，菌株X14对Ca3（PO4）：的溶解能力显著低于菌株X32和Y21，液体培养基中水溶性磷的浓度分别仅为菌株X32和Y21的22．80％和19．99％；而在限菌砂培试验中，菌株X14在玉米根际的定殖能力显著强于菌株X32和Y21，在初始接种浓度一致下，在玉米根际定殖的菌株X14较菌株X32高1个数量级；盆栽试验中接种该3株溶磷菌的处理，玉米茎粗、株高、鲜质量、地上部干质量、总干质量、地上部磷吸收量和吸磷总量均显著高于对照，但不同菌株处理间差异不显著。经过16SrDNA基因序列分析鉴定，菌株X14、X32和Y21分别为芽孢杆菌属、不动杆菌属和假单胞菌属。结论：实验室内菌株X14的溶磷能力显著弱于菌株X32和Y21，但在盆栽试验中，菌株X14对促进玉米磷吸收的效果与菌株X32和Y21相近，可能与菌株X14在玉米根际的定殖能力较强有关。溶磷菌的筛选有必要基于菌株在植物根际的定殖能力。

英文摘要：

In this study,phosphate solubilizing bacteria（PSB）were screened from rhizosphere soil and root of maize and elephantgrass using modified Pikovskaya（PVK）plate method, and phosphate-solubilizing activity of these strains was determined by measuring the soluble P concentration in National Botanical Research Institute＇s Phosphate （NBRIP）broth. In addition,3 strains designated as X14, X32, and Y21 were tested in the laboratory for their ability to colonize the rhizosphere of maize seedlings in sterile quartz sand. Finally, a pot trial was carried out in greenhouse to evaluate whether the laboratory test can predict beneficial effects of PSB on maize. The results showed that soluble P concentration in NBRIP broth of strain X14 was significantly lower than that of strain X32 and Y21 ,which was 22.80% and 19.99% of strain X32 and Y21 ,respectively. However,strain X14 was found to be a better rhizosphere colonizer than that of strain X32 and Y21, whose final population in the rhizosphere of maize seedlings expressed as CFU · g-1 was an order of magnitude higher than that of strain X32 in equal inoculum size. Under greenhouse conditions, application of PSB remarkably improved plant diameter,shoot height,fresh and dry weight, and P uptake of maize as compared to the control, but there was no significant difference between treatments inoculated with PSB. The strains X14, X32, and Y21 were identified under the genera Bacillus, Acinetobacter,and Pseudomonas using 16S rDNA sequences in comparison with GenBank database. This study showed that the phosphate-solubilizing activity of strain X14 was significantly lower than that of strain X32 and Y21 in the laboratory test, but its beneficial effect on P uptake of maize was equal to that of strain X32 and Y21 in the pot trail because of its better colonization in the rhizosphere of maize. So screening of PSB should be based on the colonization ability of strain in the rhizosphere of plant.