盐碱地小麦根际联合固氮菌数量分布研究

结合气相色谱仪和乙炔还原(ARA),采用最可能计数法(MPN)和荧光抗体(FA)染色法对盐碱地小麦根际联合固氮菌及优良固氮菌株Pseudomonassp.ChW1和Zoogloeasp.ChW6数量分布进行了测定。结果表明:小麦根际各部位均存在联合固氮菌类群,但数量相对较小、差异较大(102～106个g-1干土或根),分布趋势呈RP>RS>NRS>HP;菌株Pseudomonassp.ChW1是一种相对广谱的联合固氮菌株,在小麦根际不同部位均有分布,数量除在根系表面(RP)较多(105个g-1干根)外,其它部位较少(102～103个g-1干土或根);Zoogloeasp.ChW6菌株是一种分布谱相对较窄的联合固氮菌株,只分布于根表土壤(RS)和根系表面(RP),数量102～104个g-1干土或根。自然状况下,小麦根际固氮菌数量较少,有必要通过使用联合固氮菌接种剂提高小麦根际固氮菌种群数量,增强种群竞争力,增加根际微生物固氮总量。

Enumeration of Associative Symbiotic Nitrogen Fixation Bacteria in the Rhizoshpere of Wheat in Saline Soil

The present study was to enumerate associative symbiotic nitrogen bacteria (ASNB) which colonized on rhizosphere and in histoplant of wheat in saline soil by using Most Probable Number (MPN) and Fluorescent Antibody (FA) staining methods. The results show that there are ASNB strains exist in root - soil system, amount of the strains vary with fractions (NRS, RS, RP and HP) and rather low (10~2-10~6 bacteria /g dry soil or root) distribution tendency of the ASNB strains is as RP>RS>NRS>HP Strains Pseudomonas sp.ChW1 is widely distributed compared with strains Zoogloea sp.ChW6, and easily isolated from different fractions except for HP. Enumeration of the strains in different fractions is low (10~2～10~3 bacteria g~(-1) dry soil or root, except RP, 105 bacteria g~(-1) dry soil or root). Zoogloea sp.ChW6 strain can be isolated only in the fractions RS and RP (10~2-10~4 bacteria g~(-1) dry soil or root) of wheat. Although under natural condition, there are ASNB strains in root-soil system, and the enumeration is rather low, therefore, it is necessary to inoculate proper inoculums to increase ASNB quantity so as to improve competition of ASNB strains.