紫茎泽兰叶片凋落物对入侵地4种草本植物的化感作用

摘要

为了明确紫茎泽兰叶片凋落物对入侵地草本植物的化感作用,研究了不同浓度紫茎泽兰叶片凋落物水提液对入侵地草本植物多年生黑麦草、白三叶,辣子草和紫花苜蓿种子萌发和幼苗生长的影响,同时结合土培试验研究了叶片凋落物在入侵地土壤中的化感作用.结果表明,除多年生黑麦草外,水提液对其他3种草本植物种子萌发均产生了显著的化感抑制作用,且水提液的浓度越高抑制效果越强;低浓度水提液对紫花苜蓿和辣子草的幼苗生长存在显著化感促进作用,高浓度的水提液对除多年生黑麦草外的其他3种植物幼苗的生长存在显著化感抑制作用,水提液对多年生黑麦草幼苗生长的影响不显著;土壤中按照50g·kg-1的比例添加叶片凋落物后,显著抑制了白三叶的生长,而添加活性炭后,白三叶的单株生物量相对于未添加活性炭的处理增加71.25%,进一步证实叶片凋落物在土壤中的化感抑制作用.这说明外来入侵植物紫茎泽兰可能通过其叶片凋落物在入侵地土壤中降解,释放化感物质,抑制伴生植物的种子萌发和幼苗生长,为自身创造有利的生长环境,实现其成功入侵和扩张.%The effects of different concentrations of water extracts of A. adenophora leaf litter on the germination and seedling growth of Lolium perenne, Trifoliurn repens, Galinsoga parvifiora and Medicago sativa were determined via laboratory bioassay. The objective of the study was to elucidate allelopathic effects of A. adenophora leaf litter on herbaceous plant in invaded regions. Meanwhile, allelopathic effects ofA. adenophora leaf litter on the invaded soil were examined via pot experiments. Results showed that with the exception of L. perenne, there existed significant allelopathic inhibition effects of the water extracts on herbaceous plant seed germination. Inhibition effect increased with increasing concentration of water extract. For the growth of G parvifiora and M. sativa seedling, a significant promotion effect was noted at low water extract concentration. However, herbaceous plant seedling growth (except for L. perenne) was significantly inhibited at high water extract concentration. The effect of water extracts on L. perenne seedling growth was insignificant. Furthermore, pot experiments showed that T. repens seedling growth was significantly inhibited by 50 g · kg-1 leaf litter. T. repens biomass, however, increased by 71.25％ with the addition of active carbon (AC). This further testified an obvious alteiopathic inhibition effect of leaf litter on herbaceous plant in invaded soils. By leaf litter decomposition and releasing allelochemicals into soils, A. adenophora inhibited seed germination and seedling growth of accompanying plants, created a favorable environment for invasion and expansion.