沙蒿(Artemisia ordosica)水浸提液对4种伴生草本植物的化感作用

以生长在我国荒漠和半荒漠地区的特有植物沙蒿为供体植物,沙米、虫实、草木樨状黄芪、狗尾草为受体植物,研究了沙蒿根、茎、叶、种子水浸提液对受体植物种子发芽、幼苗生长以及根对NH~+_4和K~+吸收的化感效应的差异,为沙区植被恢复中伴生杂草种类的选择提供理论依据。结果表明:沙蒿水浸提液对4种受体植物种子发芽和幼苗生长均具有显著的化感效应,沙米、虫实、草木樨状黄芪表现为抑制作用,狗尾草表现为促进作用。不同部位沙蒿浸提液的化感作用不同,根浸提液对沙米、虫实、狗尾草的化感效应最强,茎浸提液对草木樨状黄芪的抑制最强。不同植物种及植物的不同发育时期对化感作用的敏感性也不同,在4种受体植物中,沙米受抑制最强,其次为虫实、草木樨状黄芪,且随浸提液浓度增加而显著增强,而狗尾草具有一定的耐受力,表现为促进作用。沙蒿浸提液对受体植物根长的影响最强,其次是种子发芽、苗高和幼苗干质量。浸提液显著降低沙米、虫实、草木樨状黄芪根对NH~+_4和K~+的吸收,增加狗尾草根对NH~+_4和K~+的吸收。研究结果表明雨水淋溶是沙蒿向环境中释放化感物质的途径之一,化感作用在增强沙蒿生存竞争力,扩大种群过程中起着不容忽视的作用,可能是沙蒿单优势种群落形成的原因之一。

Allelopathic effects of aqueous extracts from Artemisia ordosica on four associated herbaceous plants

We selected Artemisia ordosica as the donator species, which is an endemic plant in the desert and semi-desert regions of China. Furthermore, we selected Agriophyllum squarrosum, Corispermum hyssopifolium, Astragalus melilotoides, and Setaria viridis as the receptor species. To find suitable associated herb species, which can co-occur, we compared the different effects of the aqueous extracts of all A. ordosica tissues (root, stem, leaf, and seed) on receptor plants, including seed germination, seedling growth, and root absorption of NH₄⁺ and K⁺. The results showed that A. ordosica aqueous extracts produced significant allelopathy effect on seed germination and seedling growth of the four receptor plants. The extracts caused inhibitory effects on A. squarrosum, C. hyssopifolium, and A. melilotoides, but S. viridis was promoted. Extracts of different parts of A. ordosica exerted different allelopathic effects on the four herbs. Root extracts had the strongest allelopathic effects on A. squarrosum, C. hyssopifolium, and S. viridis, and stem extracts had the strongest inhibitory effects on A. melilotoides. The sensitivity of different plant species and developmental stages to allelopathic effects varied. A. squarrosum was the most inhibited and followed by C. hyssopifolium and A. melilotoides of the four receptor plants. With increasing concentration of A. ordosica extracts, seed germination and seedling growth significantly decreased. Conversely, S. viridis had a certain degree of A. ordosica extract resistance and was promoted. The extracts of A. ordosica had the strongest influence on root length, followed by seed germination, shoot height, and seedling dry mass, and significantly decreased the root absorption of NH₄⁺ and K⁺ in A. squarrosum, C. hyssopifolium, and A. melilotoides, but enhanced the root uptake of NH₄⁺ and K⁺ in S. viridis. Our finding indicated that rain eluviation was one of the means by which A. ordosica released allelochemicals. Allelopathy plays an important role in A. ordosica invasion and might be responsible to the formation of mono-dominant communities.