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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 method of combining high nitrogen plate with vermiculite pot was used to isolate 254 strains of soybean rhizobium isolated from 7 different fertilization treatments established in 1979 in Heilongjiang Academy of Agricultural Sciences. Rhizobium. The results of high nitrogen plate showed that with the increase of urea concentration, the number of viable cells decreased gradually, of which the concentration of urea which seriously inhibited the growth of the strain was 5 g · L-1, and only 11 strains could grow under this concentration, all from Continuous application of nitrogen fertilizer treatment. 11 strains of bacteria capable of growing under the condition of 5 g · L-1 urea were further screened by the method of simulating the vermiculite pot plant in high nitrogen environment. The dry weight of plant, total nitrogen of plant, dry weight and number of nodules The results showed that a strain 5841 with nodulation and nitrogen fixation under high nitrogen condition was obtained. According to the phylogenetic analysis of 16S r DNA sequences, it was preliminarily determined that the strain belonged to the Japanese strain of Brandyrhizobium japonicum.