油松和虎榛子不同林型根系分泌物组分及化感效应

采用气质联用（GC/MS）技术，分别对油松Piuns tabulaeformis纯林和虎榛子Ostryopsis davidiana纯林及两者混交林根际土壤中根系分泌物组分进行分析。在此基础上，应用外源法选择邻苯二甲酸、ρ-香豆酸对油松盆栽幼苗进行了化感效应测试。结果表明：根际中检测到的化合物包括有机酸类、酯类和酚酸类。其中有机酸是数量最多且比例最大的一类化合物，在油松纯林、虎榛子纯林及混交林中有机酸所占比例分别为63.82%，71.05%和69.12%；酯类分别占8.38%，12.65%和14.42%；酚酸类分别占整个组分的27.80%，16.30%和16.46%；酚酸类化合物检测到7种，包括羟基肉桂酸、ρ-羟基苯甲酸、4-羟基苯甲酸、邻苯二甲酸、3，4-二羟基苯甲酸、3，5-二羟基苯甲酸和ρ-香豆酸，混交林中没有检测到羟基肉桂酸。油松纯林中，7种酚酸的含量显著高于另外2种林型，除3，4-二羟基苯甲酸外，其余酚酸含量均为混交林的2.5倍以上，ρ-香豆酸达到8倍；与对照相比，应用外源ρ-香豆酸和邻苯二甲酸在质量浓度2.5 mg·L^－1时对油松苗高和生物量均具有促进作用，化感响应指数为正值。随着2种化合物质量浓度的增大，抑制作用加强，但ρ-香豆酸的抑制作用小于邻苯二甲酸。因此，混交林根际根系酚酸含量的降低可能是其生长优于纯林的重要原因之一。图2表1参12

Root exudate constituents and allelopathic effects from forests of Pinus tabulaeformis,Ostryopsis davidiana,and a mixed forest

In order to research the chemical communications in a pure Pinus tabulaeformis forest（PT）,an Ostryopsis davidiana forest（OD）,and a mixed forest of the two（MPO）,the components from rhizosphere soil exudates were analysedusing the gas chromatography-mass spectroscopy（GC/MS） technique.Then,the allelopathic effects of potted P.tabulaeformis seedlings were tested using exogenous phthalic acid and ρ-coumaric acid.Results showed that organic acids comprised most of the detected compounds with PT 63.82%,OD 71.15%,and MPO 69.12%;esters accounted for： PT 8.38%,OD 12.65%,and MPO 14.42%;and phenolic acids were： PT 27.80%,OD 16.30%,and MPO 16.46%.Seven phenolic acids were detected in the 3 forest types： hydrocinnamic acid（not in MPO）;ρ-hydroxybenzoic acid;4-hydroxybenzeneacetic acid;phthalic acid;3,4-dihydroxy benzoic acid;3,5-dihydroxy benzoic acid;and ρ-coumaric acid.For the seven phenolic acids PT more than MPO and except for 3,4-dihydroxy benzoic acid were 2.5 times greater in OD than MPO with ρ-coumaric acid being 8 times greater.For PT seedlings compared with the controls,after treatments of 2.5 mg·L-1 phthalic acid,the height increased,and after treatments of 2.5 mg·L-1 ρ-coumaric acid,the biomass increased.Also,their allelopathic response index was positive with an increased inhibiting effect as concentrations increased;however,the inhibiting effect of phthalic acid decreased more than ρ-coumaric acid.Thus,a lower content of phenolic acids may be one of the important reasons that mixed forests grew better than two other pure forests.