Isolation，screening and application of peanut rhizobia

【Objective】To isolate and screen peanut rhizobia of efficient nodulation and nitrogen fixation effects，and to provide theoretical basis and candidate strains for promotion and application of peanut rhizobia in field.【Method】Rhizobia were isolated and purified from soil samples collected in field by plant capture method，and their 16S rDNA sequences were amplified for molecular identification. Excellent rhizobia strains and optimal symbiotic combination were screened by reinoculation and matching tests，and effects of inoculation with the excellent strains were investigated through soil pot field tests.【Result】Fifteen strains of peanut rhizobia were isolated and purified，all belonging to Bradyrhizobium of α-proteobacteria. Two strains of peanut rhizobia，GDHS-5 and GDHS-14，with excellent symbiotic nitrogen fixation traits were screened through the reinoculation test. The matching test showed that these 2 strains had broad-spectrum nodulation，and matching Yueyou 901 with GDHS-5 produced the best effects，followed by matching it with GDHS-14. Under soil pot culture conditions，inoculation with GDHS-5 significantly increased above-ground part height，root nodule number and root nodule fresh weight of Yueyou 901（P<0.05，the same below），but no significant difference was found between strains inoculated with GDHS-14 and non-inoculated control（CK）（P>0.05，the same below）. Pod number per plant，yield and sucrose content in peanut were significantly increased by 35.82%，9.92% and 165.88% respectively after inoculation with GDHS-5 under field conditions，and no significant difference was found between strains inoculated with GDHS-14 and CK.【Conclusion】Peanut rhizobia GDHS-5 and GDHS-14 boast excellent symbiotic nitrogen fixation. GDHS-5 can efficiently fix nitrogen and has broad-spectrum nodulation and can significantly increase pod number per plant and yield of peanuts under field conditions，so it has great potential for application in field.