YA8703固氮菌的鉴定及应用研究

从云南宣威土中分离到一株YA8703固氮菌,经鉴定为褐球固氮菌云南变种(Azotobacter chroococcum var.yunnansis nov.var.)。用该菌制成的固氮菌肥作田间试验,在玉米和水稻上比同等肥力的对照增产10％～20％以上,投入产出比1∶30～1∶60。

The Identification of Azotobacter YA8703 and Its Applied Studies

The Azotobacter Strain YA8703 was isolated from gramineous plants rhizosphere soil samples collected in Xuanwei, Yunnan, China. Owing to the characteristics of large ovoid cells, rapid growth. Gram-reaction negative. G+C content of DNA 64%, forming thick-walled cysts, producing extracellular slime, motile with peritrichous flagella, it is considered to belong to Azotobacter chroococcum. However, the strain YA8703 differ from Azotobacter chroococcum Beijerinck in the utilization of starch, and, is named as Azotobacter chroococcum var. Yunnansis nov. var. Azotobacter YA8703, made nitrogen-fixing bacterial fertilizer, can not only increase the dry matter accumulation amount in wheat and maize, but also increase the grain yield about 20% to maize, above 10% to wheat and rice respectively in field tests for either mixed with these gramineous seeds or inoculated to the roots of these crops. Meanwhile, the rapid available N and P amounts in the soil were promoted obviously. The beneficial ratio of the output to investment is 1 : 30~ 1 : 50.