3种旱生禾草内生固氮菌的分离及促生性能测定

以3种多年生典型旱生禾草新农一号狗牙根(Cynodon dactylon‘ Xinnong No.1’)、沙生冰草(Agropyron de-sertorum)、偃麦草(Elytrigria repens)为材料,从根、叶组织中分离内生固氮菌株,测定其固氮酶活性、溶磷性及分泌生长素的能力,为禾草多功能促生菌剂的菌种筛选...

Isolating Endophytic Diazotrophic Bacteria from Three Xerophil Gramineae Grasses to Determine Their Nitrogen Fixation and Plant Growth-Promoting

Endophytic diazotrophic bacteria may contribute to the nitrogen nutrition and stress tolerance of host plants.In this paper,endophytic diazotrophtes were isolated from the leaf and root tissues of three typical xerophil gramineae grasses,Cynodon dactylon ’Xinnong No.1’,Agropyron desertorum(Fisch.) Schult.,Elytrigria repens(L.) Nevski,and the characteristics of nitrogenase activity,phosphate-solubilizing power and auxin(IAA) producing were investigated to screen strains for developing plant growth-promoting inocula.Results indicated that fifty eight isolates had been obtained using N-free medium and acetylene reduction assays(ARA).Nitrogenase activities differed significantly from different strains,ranging from 464 to 2338 nmol C2H4·d-1·mL-1.Nitrogenase from the strains of A.desertorum had higher activity than that from C.dactylon and E.repens.Seventeen strains out of all isolated strains showed inorganic phosphate solubilizing capacity varying from 49.93 mg·L-1 to 225.48 mg·L-1 based on the measurement of phosphate-solubilizing circle and plasma atomic emission spectrometry.Twenty-four strains had an ability to produce auxin IAA with levels of 0.61~18.54 μg·mL-1 detected.Thirty-two strains(55.2% of total tested strains),have beneficial effects on plant growth including nitrogen fixation,solubilizing phosphate and indole acetic acid production.XGEB4,XGEB26,XGEB30,XGEB64 and XGEB65 have greater potential as bio-fertilizer inocula.