无瓣海桑和互花米草群落土壤化感作用比较

Allelopathy of Sonneratia apetala and Spartina alterniflora in Soil

为揭示不同植物群落土壤在无瓣海桑(Sonneratia apetala)控制互花米草(Spartina alterniflora)中的作用,利用化感生物测定的方法,选用黑麦草(Lolium perenne)为受体,对比分析红树林无瓣海桑群落、互花米草群落以及无瓣海桑+互花米草群落土壤水提液的化感作用大小。结果表明3,种植物群落土壤水提液对黑麦草具有化感作用,无瓣海桑群落土壤和无瓣海桑+互花米草群落土壤水提液对黑麦草根长和苗高的影响表现出低促高抑的现象;ρ为0.25 g·mL-1的土壤水提液对黑麦草种子发芽和幼苗生长影响不大,1.0 g·mL-1土壤水提液对黑麦草根长和苗高产生显著影响,加入活性碳之后能减弱水提液的化感作用。ρ为0.25或0.5 g·mL-1条件下3,种土壤浸提液对黑麦草发芽率的影响无显著差异;ρ为1.0 g·mL-1的3种水提液都显著抑制黑麦草根长,而无瓣海桑群落土壤水提液表现出更强的化感作用,ρ为1.0 g·mL-1的土壤水提液显著抑制黑麦草苗高,无瓣海桑群落土壤对苗高的抑制作用显著强于互花米草群落土壤(P<0.01)。以黑麦草为受体,无瓣海桑群落土壤化感作用强于互花米草群落土壤,通过根系分泌和凋落物分解,无瓣海桑比互花米草产生更多的化感物质进入土壤,改变群落土壤化学性质,土壤化感作用可能是无瓣海桑能够控制互花米草的机制之一。

Previous studies reported that Sonneratia apetala inhibited growth of invasive weeds Spartina alterniflora through allelopathy.In order to elucidate mechanism of soil in the allelopathy,allelopathic effects of the soil extracts from three kinds of plant communities,i.e.S.apetala community（A）,S.apetala ＋ S.alterniflora community（B） and S.alterniflora community（C）,on ryegrass（Lolium perenne） were studied through allelopathic bioassay.Results show that the soil extracts from the three kinds of communities all displayed allelopathic effects,and the effects were concentration-dependent.The effects of the soil extracts from Community A and Community B were positive on growth of the roots and shoots of ryegrass when the concentration of the extracts was low,and negative when the concentration was high.The soil extracts from the three kinds of communities did not affect much germination and growth of the ryegrass when their concentration was at 0.25 g·mL-1,but did significantly to the growth of the roots and shoots of ryegrass when the concentration was raised up to 1.0 g·mL-1.The soil extract from Community A was higher than that from Community C in allelopathy inhibiting growth of ryegrass shoots（P0.01）.Through root excretion and litter decomposition,S.apetala may release more allelochemicals than any other into the soil,changing soil properties,and hence inhibiting spread of S.alterniflora.