Screening of highly-effective rhizobial strains of ‘Gongnong No.1' alfalfa in Jilin

We collected root nodules of 74 alfalfa plants in four different ecological regions in Jilin Province to survey rhizobia resources of‘Gongnong No.1'alfalfa.The results showed that root nodules were generally located in 10 cm below the fibrous roots.The nodule number and the nodule weight in various places were influenced by the implantation time,the ecological type,and the soil type.81fast-growing isolates from the root nodules were obtained.Eight rhizobial strains such as bc8,bc18,gzl59,da80,etc.were screened out by the tieback nodulation water culture,which were used to screen high efficient strains for‘Gongnong No.1'alfalfa in the greenhouse study.The results showed that the after 75 days of greenhouse cultivation,most of nodules distributed in 10 to 30cm of the roots;the stem length,root length,number of leaves,dry weight and nodule number per plant of alfalfa inoculated with rhizobia were all increased significantly(P0.05).Compared to the control,the stem length increased by 60.17%and 59.86%,and the number of leaves increased 97.92%and 95.92% by inoculated with yj34 and bc94,respectively;The root length was raised up 64.32% by gzl59;The dry weight of the plant was 288.24% and 157.14% higher than the control inoculated with gzl59 and bc54,respectively;Besides,the inoculated strains increased the nodule number per plant as well,the alfalfa plant formed more nodules by inoculated with strain yj34 than other test strains.Among 8strains selected,strains bc18,yj34,bc94 and gzl59on alfalfa were more effective than others;Of the four strains,the performance of three indigenous strains bc94 and gzl59from its host of alfalfa grew in sandy loam soil in Baicheng and Gong Zhuling,yj34 from its host of alfalfa grew in dark brown soil in a ravine of Yanji exceeded the other strains estimated by plant growth.They are the highly-effictive rhizobial strains on‘Gongnong No.1'alfalfa in Jilin Province.