无机磷溶解菌的分离筛选及其对 扁穗雀麦生长的影响

对扁穗雀麦根际溶磷微生物进行分离筛选,测定其溶磷、分泌IAA能力及对扁穗雀麦的促生效果。结果表明,不同菌株对不同无机磷底物具有选择性,以磷酸钙为磷源时,筛选的溶磷菌株都有溶磷活性,其中Br17的溶磷活性最高;以磷酸铝为磷源时,只有Br1、Br7与Br8具有溶磷活性,其中Br7溶磷活性最高。IAA测定结果显示Br4、Br8、Br17与Br24具有较强IAA分泌能力,添加生长素前体物质色氨酸时菌株分泌IAA能力增强。对培养基pH分析发现,筛选的8株溶磷菌株都为产酸型微生物。将纯化后的溶磷菌接种到扁穗雀麦无菌苗,对根长、根数、株高以及生物产量等性状考察发现接种Br8、Br13、Br17与Br24菌株对扁穗雀麦的根系影响较大,主要表现为主根变短,根数变多。接种Br7、Br8、Br13与Br24菌株促进扁穗雀麦株高增高、产量增加。综合分析,Br24在贵州地区的应用潜力最大。

Isolation and screening of inorganic phosphate-solubilizing bacteria and their effect on the growth of Bromus cartharticus

We screened rhizosphere microorganisms of bromegrass (Bromuscartharticus)and isolated bacteria with phosphate-solubilization activity.The isolated bacteria were further analyzed to quantify their phosphorus-solubilization activity,indole acetic acid (IAA)secretion capacity,and their ability to promote the growth of bromegrass.The isolated microorganisms showed differences in their ability to utilize different inorganic phos-phate substrates.All the selected strains had phosphate solubilization activity with calcium phosphate as the phosphorus source,whereas only strains Br1 ,Br7 and Br8 were able to solubilize phosphate with aluminum phosphate as the phosphorus source.Strain Br7 had the strongest phosphate-solubilization ability.Strains Br4, Br8,Br17,and Br24 secreted relatively large amounts of IAA,and IAA secretion was enhanced when exoge-nous tryptophan (an IAA precursor)was added.Analyses of the medium pH indicated that all eight isolated strains were acid-producing bacteria.The root length,root number,plant height,and total biomass of brome-grass inoculated with these isolated strains were measured.Strains Br8,Br13,Br17,and Br24 strongly affect-ed root growth,resulting in a shorter main root but more abundant roots.Strains Br7,Br8,Br13,and Br24 increased bromegrass plant height and biomass.These results indicate that strain Br24 has great potential to improve the growth of bromegrass in Guizhou province.