关键词: 黄芪, 镉胁迫, 生长发育, 矿物营养元素, 次生代谢

Abstract: The experiment was conducted to study the effects of different concentration Cd treatments on the growth, the adsorption and translocation of mineral elements, and the secondary metabolism of Astragalus membranaceus(Fisch.) Bunge(A. membranaceus), a traditional Chinese herb by employing a hydroponic system. The treatments of 25-200 μmol·L^-1 Cd significantly inhibited the biomass growth and induced the increasing of malondialdehyde(MDA) content in whole plant and the decreasing of photosynthetic pigment contents in the new leaves, obviously exhibiting adverse effects. The Cd adsorbed by the plant dominantly accumulated in the roots. The greatest proportion of the shoots Cd was accumulated in its underpart, and orderly followed by the middle and the upper parts. It suggested that the seedlings took the advantage of Cd compartmentalization to minimize the adverse impact on the growing tissues of the shoots. Cd exposure hindered the adsorptions and translocations of a variety of mineral nutrition elements. However, the contents of Ca and Mg markedly enhanced by the Cd treatments in the upper and under shoots, respectively. We presumed that this might play positive roles in reducing the harms of Cd in the growing and old leaves. Furthermore, the contents of four isoflavonoids were elevated by the Cd treatments in roots of the seedlings. On the contrary, the contents of astragaloside Ⅰ-Ⅳ were depressed. It was implied that the isoflavonoids rather than astragalosides helped the seedlings of A. membranaceus to counteract Cd stress in their roots.

Key words: Astragalus membranaceus, cadmium stress, development, mineral nutrition element, secondary metabolism