陕北地区苹果根际促生菌的筛选及其促生效应

Screening of Growth-promoting Bacteria of Apple Rhizosphere Soil and Its Growth-promoting Effect in Northern Shaanxi

为进一步开发苹果根际促生菌资源,以陕北苹果树根际土壤为材料进行根际促生细菌的筛选.以溶磷、解钾和产铁载体作为标准,测定初筛菌株的多种促生能力,并通过16S rDNA序列同源分析,对筛选出的促生效果最好的菌株进行分类鉴定,并采用单菌单独接种和多菌混合接种的小麦盆栽试验,测定其促生效应.结果表明:从陕北不同产地苹果根际土壤中筛选获得131株细菌,具有溶磷能力的菌株共17株,占总分离菌株的10.68%,其中11株细菌能够溶解无机磷,6株细菌能够溶解有机磷;可产铁载体的有24株,占总分离菌株的18.32%,YS-28和YC-31具有解钾能力.基于16S rDNA序列比对和系统发育分析将其中的24株归属于芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)、白色杆菌属(Leucobacter)、红球菌属(Rhodococcus).从中筛选出属于芽孢杆菌属(LC-22、YC-31、LC-19)和假单胞菌属(LC-2)的高活性菌株的小麦盆栽试验结果表明,与对照组相比,经LC-22、YC-31和LC-19混合菌液处理,小麦幼苗鲜质量增加96.12%;经LC-22、LC-19和LC-2混合菌液处理,小麦叶绿素含量增加41.31%.可见:从苹果根际土壤中所筛选的促生菌株,可以作为微生物肥料储备菌种.

The rhizosphere soil of apple tree in northern Shaanxi area was used a saseparation material to screen growth-promoting bacteria.Based on the analys is of 16S rDNA sequences,the phylogenetic relationships of representative strains were determined,the activity of phosphorus and potassium dissolution and siderophore production were tested,and a pot experiment with a single inoculation and multi-microbe mixed inoculation was conducted to determine their growth-promoting effect.The re-sults showed that a total of 131 strains of bacteria were isolated from apple rhizosphere soil in fourd if-ferent counties and districts in northern Shaanxi,and the growth-promoting ability were measured.Among them,17 strains had phosphorus-soluble ability,accounting for 10.68% of the total isolates,11 strains could dissolve organic phosphorus and 6 strains could dissolve inorganic phosphorus.24 strains could produce siderophores,accounting for 18.32%.In addition,strains YS-28 and YC-31 could dis-solve potassium.Subsequent 16S rDNA sequence alignments and phylogenetic analyses revealed that these strains could be categorized into 4 genera(Bacillus,Pseudomonas,Leucobacter and Rhodococ-cus).4 highly active strains were screened out,in which LC-22,YC-31,LC-19 belonged to Bacillu,and LC-2 belonged to Pseudomonas.Compared with the control,under mixed treatment of LC-22,YC-31 and LC-19,the fresh mass of wheat seedlings increased by 96.12%;under mixed treatment of LC-22,LC-19 and LC-2,the chlorophyll content in wheat seedlings increased by 41.31%.In conclusion,the growth-promoting bacteria screened out from rhizosphere soil of apple tree have a strong potential to promote rice growth,and can be used as a microbial fertilizer reserve for bacteria.This study laid a solid foundation for the further development of microbial fertilizer.