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水稻根圈的生物固氮能力高于非根圈,原因可能是植物根放出较多的有机物。为进一步搞清这一点,用乙炔还原法测定了根圈、根面、非根圈的生物固氮能力。同时用~(14)C示踪法对根放出的有机物作了测定。此外,为了比较,对C_3作物玉米也进行了同样实验。试验结果小结如下。 1.水稻的生物固氮能力高于玉米,但两者都是根面>根圈>非根圈。 2.水稻根圈的生物固氮能力,虽在幼穗形成期显得很高;但玉米根圈的固氮能力和生育期之间并无固定的变化趋势。 3.置于暗处,生物固氮能力立即减退,减退的程度因植物种类及生育期不同而有差异。 4.~(14)C光合作用示踪测定发现,根圈放出物的水溶部分中,水稻的糖组分含量最高,玉米的有机酸组分最高。 5.生物固氮能力与根圈中糖和有机酸含量之间,相关性较高,但与氨基酸含量无明显相关。
The biological nitrogen fixation ability of rice rhizosphere was higher than that of non-rhizosphere, which may be due to the release of more organic matter from plant roots. To further clarify this point, with the acetylene reduction method to determine the root circle, root surface, non-root circle biological nitrogen fixation capacity. At the same time ~ (14) C tracer method to determine the release of organic matter root. In addition, the same experiment was conducted on C_3 crop corn for comparison. The test results are summarized as follows. 1. The biological nitrogen fixation ability of rice is higher than that of corn, but both are root surface> root ring> non-root ring. The bio-nitrogen fixation ability of rice rhizosphere was very high at panicle formation stage, but there was no fixed change trend between corn rhizosphere nitrogen fixing ability and growth period. 3 placed in the dark, biological nitrogen fixation immediately diminished, the extent of decline due to plant species and growth period vary. 4. ~ (14) C photosynthesis tracing assay found that the root circle of the water-soluble part of the output, the highest content of sugar components of rice, corn, the highest organic acid components. There was a high correlation between biological nitrogen fixation ability and the content of sugar and organic acid in root circle, but no significant correlation with amino acid content.