汞对毛苕——根瘤菌共生固氮的影响

本文以浓度梯度法研究了重金属离子二价汞对豆科根瘤菌和寄主毛苕生长结瘤固氮酶活性的影响。研究表明,根瘤菌各菌株间对Hg~(2 )的忍耐程度有差异。当Hg~(2 )浓度为2ppm时,多数菌株仍能正常生长;5ppm时,受不同程度的抑制;10ppm时,受到严重抑制,有些菌株完全不能生长;20ppm以上,所有供试菌株完全不能生长。在水培条件下,当Hg~(2 )达10ppm、土培为50ppm时,毛苕的结瘤固氮受影响;水培20ppm、土培200ppm以上时,植物根部完全不结瘤。本工作初次阐明了汞对某些根廇菌-寄主毛苕的毒害,为鉴别污染程度和农业环境质量评价提供了科学依根。

EFFECT OF MERCURIC ION ON SYMBIOTIC NITROGEN FIXATION OF VETCH (VICIA VILLOSA)

The effect of Hg²⁺on nodulation and nitrogen fixation of rhizobium and vetch host has been studied. The result shows that the tolerant degree to Hg²⁺ among various rhizobia strains are different. Most strains grow normally in 2 ppm of Hg²⁺. They are, however, inhibited at different degree when the rhizobia strains are in 5 ppm. And they are seriously inhibited in 10 ppm, with only a few strains which can stand 20 ppm. All the rhizobium strains tested can not grow in 30 ppm of Hg²⁺.The investigation of vetch shows that nodulation of vetch will be effected when Hg²⁺ goes up to 10ppm under water culture and 50 ppm in soil culture. In case Hg²⁺ goes up to 20 ppm in water culture and runs high over 200 ppm in soil culture, all the nodule will not be formed.