耐高氮优良大豆根瘤菌株的筛选与鉴定

Screening and Characterization of Superior Nitrogen-Tolerance Soybean Rhizobia

采用高氮平板与蛭石盆栽相结合的方法,以黑龙江省农业科学院1979年设立的黑土长期定位试验7种不同施肥处理中分离到的254株大豆根瘤菌为材料,筛选耐高氮的优良大豆根瘤菌。高氮平板结果显示:随着尿素浓度的增加,可生长的菌株数量逐渐减少,其中严重抑制菌株生长的尿素浓度为5 g·L-1,该浓度条件下只有11株菌能够生长,均来自连续施用氮肥的处理。进一步采用模拟高氮环境蛭石盆栽的方法,将能在5 g·L-1尿素条件下生长的11株菌进行复筛,以植株干重、植株全氮量、根瘤干重和数量作为评价指标,获得1株在高氮条件下具有结瘤固氮能力的菌株5841。经16S r DNA序列系统发育分析,初步确定该菌株属于日本慢生大豆根瘤菌(Brandyrhizobium japonicum)。

The superior nitrogen-tolerance rhizobia strains were screened from 254 strains of rhizobia,which were isolated from7 different fertilization treatments in long-term black soil fertility and fertilizer efficiency experiment station adopting high-concentration nitrogen plate method and vermiculite pot. The black soil fertility and fertilizer efficiency experiment station were constructed by Heilongjiang Academy of Agricultural Sciences in 1979. The results obtained from high-concentration nitrogen plate method indicated that increasing urea concentration had an increased bacteriostatic effect. Urea concentration which could seriously inhibit growth of strains was 5 g·L^- 1,only 11 strains could grow in this urea concentration,which were all isolated from continuous application of nitrogen fertilizer. In the subsequent high-concentration nitrogen vermiculite pot experiment,the best strain 5841 were selected according to the plant dry weight,number of nodules,dry weight of nodules and total N content of the plant,which had the ability of nodulation nitrogen fixation in high-concentration nitrogen. Based on 16 S r DNA sequence phylogenetic analysis,the strain 5841 was identified as Brandyrhizobium japonicum.