云雾山铁杆蒿茎叶浸提液对封育草地四种优势植物的化感效应

为了揭示铁杆蒿群落在植被演替中的作用,通过研究铁杆蒿茎叶浸提液对铁杆蒿草地4种优势植物(百里香、大针茅、本氏针茅和赖草)的种子萌发及幼苗生长的干扰,结果表明:高浓度的铁杆蒿浸提液(甲醇浸提液和水浸提液)使得百里香、大针茅、本氏针茅和赖草的种子发芽指数降低,发芽率、芽长和根长低于对照,种子平均发芽时间延长达1.13-2.16 d。而低浓度浸提液(0.005 g/mL)使得百里香的发芽要高于对照11.63%(水浸提液)、15.12%(甲醇浸提液)。在幼苗生长期,铁杆蒿浸提液对4种受试植物幼苗芽和根的生长受到不同程度的抑制,不同浓度的浸提液对植物的化感作用强度不同,随浓度的增加,抑制作用越强,0.1 g/mL相对其他浓度有显著性差异;其中0.005 g/mL浸提液对本氏针茅和赖草的幼苗生长有促进作用,幼根生长高出对照19.00%、16.06%,水浸提液对幼芽促进了2.33%、9.06%,在0.1 g/mL浓度下,本氏针茅或大针茅的生长完全受到抑制,芽长和根长抑制率为100%;同一浓度下的不同浸提液对植物的抑制作用也不同,其中百里香对铁杆蒿浸提液的敏感度是最低的;甲醇浸提液的化感作用要强于水浸提液。在封育过程中,百里香群落向铁杆蒿群落的过渡,铁杆蒿的化感作用是该草地演替的一个重要影响因子。

Allelopathic effect of extracts from Artemisia sacrorum leaf and stem on four dominant plants of enclosed grassland on Yunwu Mountain

We studied the allelopathic effects of Artemisia sacrorum on vegetation succession in an A. sacrorum grassland, a typical grassland on Yunwu Mountain. We tested three different concentrations(0.005 g/mL, 0.01 g/mL and 0.1 g/mL) plus controls of both water and methanol extracts from leaves and stems of A. sacrorum on seed germination and seedling growth of four dominant or accompanying species (Thymus mongolicus, Stipa grandis, S. bungeana, and Leymus secalinus). Higher concentrations of both methanol and water extracts reduced seed germination rates as well as seedling root and shoot growth in all four species relative to controls. Seed germination times were prolonged by 1.13-2.16 d. At low extract concentrations (0.005 g/mL), however, the germination rate of T. mongolicus was 11.63% higher with water-extract treatment and 15.12% higher with methanol-extract treatment. The allelopathic effects of A. sacrorum extracts were concentration-dependent, with a larger inhibitory effect at greater concentrations. The inhibitory effect at 0.1 g/mL was significantly different compared with other concentrations. Extracts of 0.005 g/mL accelerated seedling growth of S. bungeana and L. secalinus; their radicles were 19.00% and 16.06% longer than control groups, respectively. The 0.005 g/mL water extract enhanced S. bungeana and L. secalinus by 2.33% and 9.06% in the shoot length respectively. The growth of both Stipa species was restrained by 0.1 g/mL extracts, with 100% inhibition of some growth parameters (the root length and the shoot length). The methanol extracts had greater effects than the water extracts. Of the four species tested, T. mongolicus was the least sensitive to A. sacrorum extracts, suggesting that the A. sacrorum influences the community structure after replacing T. mongolicus community. The allelopathy of A. sacrorum is a very important factor in vegetation succession on Yunwu Mountain.