氮素波动对反枝苋和大豆最大净光合速率和光合氮利用效率的影响

The Effects of Nitrogen Fluctuation on the Maximum Net Photosynthetic Rate and Photosynthetic Nitrogen Use Efficiency of Redroot Pigweed(Amaranthus retroflexus) and Soybean(Glycine max)

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研究了反枝苋和大豆(Glycine max)最大净光合速率(Pmax)和光合氮利用效率(PNUE)的变化情况。结果表明,无论在何种氮素波动条件下,苗期反枝苋的Pmax均显著高于大豆,而开花结荚期大豆的Pmax则略高于反枝苋;无论苗期还是开花结荚期,反枝苋的PNUE均高于大豆;说明在入侵初期,反枝苋能够保持高的光合能力,对氮素资源进行高效利用,这很可能是其迅速抢占生态位,从而成功入侵的原因之一。

In order to study the adapting mechanism of invasive weed,Amaranthus retroflexus response to the mtrogen fluctuations, the competition mechanism between Amaranthus retroflexus and crops in the process of invading agro-ecosystem, the maximum net photosynthetic rate （Pmax） and photosynthetic nitrogen use efficiency （PNUE） of A. retroflexus and Glycine max response to nitrogen fluctuations were studied based on the method of imitating different nitrogen fluctuations. The results showed that the Pmax. of A. retroflexus was significantly higher than that of G. max in the seedling stage regardless of N fluctuations types, whereas the Pmax of G. max was slightly higher than that of A. retroflexus in the flowering and podfill stage. The PNUE of A. retroflexus was higher than that of G. max in the two stages. In the early period of invasion process ,A. retroflexus had high Pmax and PNUE ,which might be one of the reasons to explain why it could occupy the niche quickly, and successfully invaded the agro-ecosytsem.