Abstract: Nutrient characteristics of soils collected from five main plant species in Potentilla acaulis degraded grassland were analyzed and the allelopathy of P. acaulis ethanol extract on the seedling growth of four dominant species receptors (Stipa krylovii, Artemisia frigida, Leymus chinensis and Agropyron cristatum) in P. acaulis degraded grassland were determined. The allelopathic ability of P. acaulis was discovered. The reason of P. acaulis becoming the dominant plant of degraded grassland was explained from the aspect of chemical ecosystem. Results were as follows: only available nitrogen content was lower in soils under P. acaulis than that beneath A. frigida, whereas others were higher. Allelopathic activities were related to extract concentration, test species and extract source. Ethanol extract of whole P. acaulis plant strongly inhibited the shoot and root growth of S. krylovii, and the inhibition was strengthened with extract concentration increasing. However, extracts showed a "low-promotion and high-inhibition effect" on the shoot growth of L. chinensis and A. frigida. The critical concentration value of extracts was 0.004 g·mL^-1. Extracts of P. acaulis aboveground parts presented strong promotion on A. cristatum’s seedling growth at 0.002 g·mL^-1 concentration. Allelopathy of P.acaulis underground parts were stronger compared with aboveground parts. Root growth had higher sensitivity than the shoot growth of all tested species seedlings. The greatest inhibition for seedling growth occurred in S. krylovii, followed by L. chinensis, A. frigida, and then A. cristatum.

Key words: Potentilla acaulis, Ethanol extracts, Ecology related species, Allelopathy

摘要： 用土壤营养成分分析法及室内生物检测方法,研究星毛委陵菜(Potentilla acaulis)退化草地主要植物斑块土壤的营养成分,以及星毛委陵菜地上、地下部分的乙醇浸提物对4种受体植物克氏针茅(Stipa krylovii)、羊草(Leymus chinensis)、冰草(Agropyron cristatum)和冷蒿(Artemisia frigida)幼苗生长的影响,以期从化学生态学角度阐明星毛委陵菜作为草原沙化的阻击者,对典型草原优势植物种群存在的化感作用。结果表明:星毛委陵菜斑块土壤的营养成分除有效氮含量低于冷蒿斑块土壤外,其他营养成分含量均最高;星毛委陵菜地上、地下部分乙醇浸提物的化感效应因受体植物和浸提物浓度不同而存在显著差异。星毛委陵菜地上、地下部分浸提物均显著抑制克氏针茅幼苗的生长(P＜0.05),且随着浸提物浓度的增大抑制作用增强;对羊草和冷蒿幼苗生长具有"低促高抑"的效应:浓度≤0.004 g·mL^-1时促进羊草和冷蒿幼苗苗的伸长生长,浓度＞0.004 g·mL^-1时则表现为抑制作用;浓度为0.002 g·mL^-1时,地上部分浸提物能够促进冰草幼苗苗和根的伸长生长。星毛委陵菜乙醇浸提物对受体植物幼苗根生长的抑制作用要大于对幼苗苗生长的作用,并且星毛委陵菜地下部分的化感作用大于地上部分的。对星毛委陵菜化感作用最敏感的植物是克氏针茅,其次是羊草、冷蒿和冰草。

关键词: 星毛委陵菜, 乙醇浸提物, 生态相关种, 化感作用