马尾松根际土壤有机酸类物质的化感作用

有机酸是植物根系向外界分泌最主要的一类化感物质。为探讨马尾松根际土壤有机酸类物质是否具有化感效应及其作用类型,以马尾松林下植物(狗尾草、狼尾草)和南方常见水保植物(狗牙根、巴哈雀稗)为受体,通过生物检测等技术手段,研究马尾松根际土壤有机酸类物质对受体植物种子发芽率、幼苗苗高、根长及干质量生长指标的影响。结果表明:(1)4种受体植物化感综合效应在16.4%~41.1%,狗牙根最弱,狗尾草最强;3种有机酸物质化感综合效应在21.6%~34.6%,以脱氢松香酸最强,硬脂酸最弱。(2)有机酸物质对受体植物指标影响最大的为根长,对照抑制率为42.7%,发芽率最小,对照抑制率为13.3%,狗牙根发芽率和狼尾草干质量表现出一定的促进作用。(3)3种有机酸的化感作用类型主要包括,低促高抑、随浓度升高抑制增加和无明显浓度效应。因此,脱氢松香酸很可能是马尾松的主要有机酸化感物质,且从化感作用角度,狗牙根可以考虑作为马尾松林下植被恢复的先锋植物。

Allelopathic Effect of Organic Acids from Pinus massoniana Rhizosphere Soil

Organic acids are the main allelochemicals that plant root secretes to the soil environment.In or-der to discuss the allelopathy of organic acids from Pinus massoniana rhizosphere soil, the effects of organic acids on seed germination,root length,shoot height and dry weight of four southern common herbs,i. e. Setaria viridis,Pennisetum alopecuroides,Cynodon dactylon and Trifolium repens,were studied. Three kinds of organic acids from Pinus massoniana rhizosphere soil had obvious allelopathic inhibition effects on Setaria viridis,Pen-nisetum alopecuroides and Trifolium repens under 10,1 and 0.1 mmol/L concentrations,no obvious influence on Cynodon dactylon. Dehydroabietic acid was the main organic acid of allelochemicals from Pinus massoniana. Root length was sensitive to allelopathic effect of organic acid on receptor. Moreover,organic acid had positive effect on seed germination of Cynodon dactylon and plant dry weight of Pennisetum alopecuroides. For different concentrations of organic acids from Pinus massoniana,no obvious differences in allelopathic effects were found on Cynodon dactylon,but the inhibition effects were improved with the increase of extract concentrations for Setaria viridis,and low-promoting and high-repressing effects for Pennisetum alopecuroides.Therefore,dehydroabi-etic acid was likely to be the organic acid of allelochemicals from Pinus massoniana.From the perspective of al-lelopathy,Cynodon dactylon can be considered as a pioneer plant for Pinus massoniana understory restoration.