氮素资源波动对反枝苋与大豆硝酸还原酶活性的影响

为探讨外来杂草反枝苋(Amaranthus retroflexus)在入侵农田生态系统过程中对氮素资源波动的适应规律及与作物的竞争机制,采用人工模拟不同氮素波动条件的方法,比较研究了反枝苋和大豆(Glycine max)体内氮素同化关键酶——硝酸还原酶活性的变化情况。结果表明,大豆和反枝苋不同器官的硝酸还原酶活性均能对环境中的氮素添加作出快速的响应,这可能与硝酸还原酶是一种诱导酶有关;大豆硝酸还原反应主要在叶和根部进行,而反枝苋则主要在茎和繁殖器官中进行;无论是大豆还是反枝苋,在单栽其各器官的硝酸还原酶活性均大于混栽,说明种间竞争作用要明显大于种内竞争,种间竞争会显著降低植物体内氮代谢的水平。

The Effects of Nitrogen Resource Fluctuation on Nitrate Reductases Activities of Redroot Pigweed(Amaranthus retroflexus) and Soybean(Glycine max)

In order to study the adapting mechanism of invasive weed,Amaranthus retroflexus response to nitrogen fluctuations,and the competition mechanism between Amaranthus retroflexus and crops in the invading agro-ecosystem,the nitrate reductase(one of the key enzymes of nitrogen assimilation) activities of Amaranthus retroflexus and Glycine max response to different nitrogen fluctuations were studied based on the method of imitating different nitrogen fluctuations.The results showed that the nitrate reductase activities in different organs of Glycine max and Amaranthus retroflexus could respond to nitrogen fluctuation rapidly,which may be due to nitrate reductase belong to a kind of inducible enzymes.Nitric acid reduction reaction of Glycine max carried out mainly in leaves and roots,while that of Amaranthus retroflexus mainly carried out in the stems and reproductive organs.Both the nitrate reductase activities of Glycine max and Amaranthus retroflexus were greater in mono-cropping than in mixed-cropping,implying that the interspecific competition was more severe than intraspecific competition,and interspecific competition would significantly reduce the level of nitrogen metabolism in Glycine max and Amaranthus retroflexus.