Abstract: Phosphate-solubilizing bacteria are important for the nutrient supply and performance of legume plants because they can not only increase the available phosphorus in soils but also improve the nodulation and nitrogen fixation of rhizobia.In the present paper,characteristics of IAA secretion and phosphate dissolving of 5 strains of phosphate-solubilizing bacteria and the effect of inoculation of phosphate-solubilizing bacteria on alfalfa growth were studied using broth culture method and pot culture experiment,respectively.The results show that all the strains test could solubilize phosphate with great capability difference among strains.The strain LM18 showed the maximum capacity to solubilize phosphate(300.3 mg·mL^-1).All the strains had the ability to produce IAA detected by colorimetric method.The maximum secretion amount was 17.95 μg·mL^-1(LM12)while the minimum was 3.75 μg·mL^-1(LH6).Every strain showed great benefit to alfalfa height,stem diameter,dry weight,dry weight to fresh weight ratio,and the leaf to stem ratio of alfalfa in comparison with control.In summary,strains LM12 and LM18 showed strong capability in phosphate dissolving and IAA secretion and could be used as potential strains for biofertilizer manufacture.

Key words: Phosphate-solubilizing bacteria, IAA secretion, Phosphate dissolving capacity, Alfalfa

摘要： 植物根际溶磷菌不仅可以提高植物对土壤磷素的利用率,同时可以促进根瘤菌的结瘤和固氮作用。利用液体培养法对5株溶磷菌的溶磷特性和分泌IAA能力进行研究,并通过盆栽试验研究接种溶磷菌对苜蓿(MedicagosativaL.)生长的影响。结果表明:各供试菌株溶磷能力差异较大,溶磷能力最强的是LM18(300.3 mg/mL);菌株都有分泌IAA特性,最大分泌量为17.95μg/mL(LM12)。接种溶磷菌后苜蓿株高、茎粗、干重、干鲜比和叶茎比都比对照明显增加。因此,溶磷能力和分泌IAA能力较强的菌株(LM12和LM18)可作为研制微生物肥料的优良菌株。

关键词: 溶磷菌, 分泌IAA, 溶磷量, 苜蓿