大叶油草及其主要伴生杂草狗牙根、马唐光合特性的研究

通过对地毯草及其伴生种杂草狗牙根和马唐进行光照梯度的模拟试验，分析大叶油草及其伴生种狗牙根和马唐的净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和水分利用率（WUE）对光合有效辐射（PAR）增强的响应。结果表明，大叶油草Pn、Tr、Gs均低于狗牙根和马唐；大叶油草和狗牙根的WUE相近，但马唐的WUE高于大叶油草和狗牙根的1倍。大叶油草的水分利用能力相对较低，若不加强管理，大叶油草在与杂草竞争中有可能被马唐和狗牙根等杂草取代。

A Comparative Study of Photosynthetic Characteristics Among Axonopus Compressues, Cynodon Dactylon and Digitaia Sanguinalis

Through the experiment of different photosynthetic active radiation(PRA), the photosynthetic physiological characters of Axonoupus compressures, Cynodon dactylon and Digitaia sangunalis are measured. A comparison of the responses of net photosynthesis rate(Pn), stomatal conductance(Gs), transpiration rate(Tr) and water use efficiency (WUE) to the enhancement of PAR is made. The result is summarized as follow: under present atmosphere CO2 concentration, Pn, Gs, Tr and WUE of the Axonopus compressus is lower than the Cynodon dactylon and Digitaia sanguinalis, WUE of the Digitaia sanguinalis is more than one time WUE of the Axonopus compressus. We consider that a study of the responses of photosynethetic physiological characters of Axonopus compressus, Cynodon dactylon and Digitaia sanguinalis to the enhancement of PAR will contribute to revealing and comparing different plants adapted to the environments. In view to the lower WUE of the Axonopus compressus, management should be strengthened, otherwise Anoxopus compressus could be replaced by weed like Cynodon dactylon and Digitaia sanguinalis.