| Seventeen peanut rhizobial strains ware collected and purified from 8 regions of Liaoning province. In the present study, cross-inoculation experiments were preformed in cowpea and soybean, physiological and biochemical characteristics were determined,16S rDNA and nifH gene sequence analysis and the restriction fragment length polymorphism (RFLP) of 16S rDNA and 16S-23S rDNA IGS region of the bacterial isolates were then performed to analyzed the phylogenetic position of strains. Screening of one high efficient strain and application of inoculation treatments and different nitrogen fertilizer.Cross inoculation test indicates that isolates can nodulate cowpea but not soybean.The results of colony morphologies, growth rates and alkalinization primarily illustrat that the isolates are Bradyrhizobium. The cluster analysis based on physiological and biochemical characteristics is divided into three groups on the 80% level, while the isolates 4, F1, F3 and E1 did not cluster, showed the lower similarity between isolates and sites.In this study, the analysis using the 16S rDNA and nifH gene sequences of the isolates indicat that they all belong to the genus B. japonicum, in other words, B. japonicum is the dominant species of Liaoning province. The isolates are identified into four clusters based on the 16S rDNA phylogenetic analysis. While two clusters are identified in phylogenetic tree based on nifH gene sequences. There are high similarity between the two trees, group A on nifH tree corres-ponding to group Ⅰ on 16S rDNA tree, while group B on nifH tree corresponding to group Ⅱ, Ⅲ and Ⅳ on 16S rDNA tree.Thirteen polymorphism are variable across all observations in 16S rDNA RFLP, results show that besides strains in Kangping, strains with same RFLP type usually belong to the similar place; Six different IGS types are variable from the 17 isolates, the result is similar with 16S rDNA RFLP, but there are some strains from different sites belong to the same group. The result imply that there are some association between geographical factor and phylogenetic diversity of indigenous rhizobium isolates.The result of nodule amount shows that compare with the no-inoculation treatment, the inoculation treatments can significantly improve the peanut nodule number, nodule amount is not significant between the no-inoculation treatment, and the nodules are little, means less rhizobia in local soil, inoculant had a dominant position in competition with the indigenous bacteria.The results of different treatments on plant enzyme activity, soil enzyme activity, available nitrogen, phosphorus and potassium in different layers, total nitrogen, phosphorus and potassium content in plant organs show that, compare with control, all treatments are in significance level, The inoculation treatments are better. As the soil layer deepen, available nitrogen, phosphorus and potassium content is on the decline; Total nitrogen and total phosphorus content are higher in leaf than in stem, and total potassium content is higher in stem than in leaf. Taken together, applied nitrogen fertilizer is not the more the better, together with bacterial fertilizer can achieve the ideal effect.The result of different treatments on plant laboratory test and investigation of actual output in mature stage show that, compare with control, all treatments are in significance level, the treatment of N1/3J1 has the best effect on plant laboratory test, followed by N2/3J1; N1/3J1 has the highest yield,19.54% higher than control, the second is N2/3J1,11.49% higher than control. Overall, the inoculation treatments have advantage on increase the yield, excessive use of nitrogen fertilizer can’t achieve the satisfying effect. |
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