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作 者 ：宋未,徐瑞姬,吴天云,尤崇杓

期 刊 ：核农学报 1988年 2卷 03期 页码：177-183

关键词：红萍；固氮；分子氮；

Keywords:azolla, nitrogen fixation, molecular hydrogen,

摘 要 ：本工作研究了分子氢对不同生长条件下三种红萍:细绿萍(Azollsa filiculoides),卡洲萍(Azolla caroniana)和小叶萍(Azolla microphylla)的固氮活性的支持作用,结果表明,在5000—20000lx不同光照强度下,分子氢对红萍固氮活性均有支持作用,当光照强度为10000lx时,10％的分子H_2可使红萍的固氮活性增加30—80％,在5000lx弱光条件下,相同浓度分子氢使红萍固氮活性增加的幅度比10000lx光照时大。在相同的光照条件下,大叶萍的固氮活性较高,分子氢对其固氮活性的支持作用也较强,说明了在萍藻共生体系中,光能利用、固氮效率与分子氢利用效率呈正相关。同时,分子氢对于红萍固氮活性受尿素毒害所致的抑制也有减慢作用。在培养液中尿素浓度超过5ppm时,红萍的固氮活性受到抑制,当尿素浓度达到50ppm时,其固氮活性抑制率达50—60％,但20％的分子氢可使其固氮活性恢复到正常培养下的70％以上。在一定的尿素浓度范围内,红萍固氮活性受抑程度愈大,分子氢对其减慢的作用也愈强。

Abstract:Azolla filiculoides, Azolla caroliniana and Azolla microphylla have been used for studies on the effects of H2 on nitrogen fixing activity at different light intensities and different urea concentrations in the midia.The results indicated that the H2 could promote nitrogen fixation of Azolla at different light intensities. 10.% of H2 concentration in the gas phase stimulated the acetylene reduction activity(ARA)of Azolla, ARA was increased up by 30-80% at 10,000 lx of illumination, while . the same concentration of H2 could promote the Azolla ARA more effeciently at 5,000 lx of rather weak illumination.The ARA of Azolla microphylla was higher than, the other two species and the H2 promoting ARA of A.microphylla was also more effecient at the same illumination level.It is suggested that the utilization availability of light energy and H2 are positively correlative with nitrogen fixing rate in Azolla-Anabaena symbiotic association.The H2 could derepress the Azolla ARA repressed by urea of which the concentration in the medium were over 5 ppm.50 ppm of urea repressed Azolla ARA by 50-60%. However the adding of 20% of H2 in the gas phase could make the Azolla ARA up to 70% of normal one. The more repressing the urea on Azolla ARA, the more derepressing of H2 within a certain urea concentration range.

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