Abstract: The effects of arbuscular mycorrhizal fungus (Glomus mosseae and G.versiforme) on the dry weight and absorbing phosphorus of Poncirus trifoliata seedlings and its root excreting organic acids under low-phosphorus stress with the Al-P as phosphorus source and poncirus trifoliata seedlings as experimental material were studied in sand culture and sterilization greenhouse.The results showed that the inoculation of AM not only markedly increased the dry weight of overground part and underground part of Poncirus trifoliata,which raised by 16.79%~135.25%,but also remarkably increased phosphorus uptake with the contribution rate up to 17.04%~71.95% (G.m>G.v).Fertilizing Al-p could observably raise the contribution rate.The kinds of organic acid which were secreted by the root systems of AM fungi inoculation were different from the control.We only detected six acids (oxalic acid,malic acid,lactic acid,acetic acid,maleic acid and citric acid) in non-inoculated treatment materials,while 7 acids (oxalic acid,tartaric acid,malic acid,lactic acid,acetic acid,citric acid,succinic acid) in G.m treatment materials,and also tartaric acid and no maleic acid detected in G.v treatment materials.Inoculation also increased the content of organic acid secretion (increased by 19.80~56.87 mg/kg) of trifoliate root,and the application of AlPO₄ greatly increased organic acid content (increased by 20.06~21.84 mg/kg);uninoculated plant root secreted a bit of organic acid;Mycorrhizal poncirus trifoliata seedlings excreted malic acid (42.87%),citric acid (39.22%) and oxalic acid (12.06%).

Key words: arbuscular mycorrhizal fungus, Poncirus trifoliata seedlings, root, low phosphorus stress, insoluble phosphate, organic acid

摘要： 在温室沙培灭菌条件下,以Al-P为磷源、枳为试材、Glomus mosseae (G.m)和G.versiforme (G.v)为菌剂,研究低磷胁迫下AM真菌对枳实生苗干物重、吸磷效应及根系分泌有机酸的影响。结果表明,接种AM真菌显著增加枳地上部、地下部干物重,增幅16.79%~135.25%;同时显著增加其吸磷量,菌丝对植株的吸磷贡献率为17.04%~71.95%(G.m>G.v),施Al-P显著提高菌丝吸磷贡献率。接种AM真菌的根系分泌的有机酸种类与对照有所不同,未接种处理枳分泌的有机酸有草酸、苹果酸、乳酸、乙酸、顺丁烯二酸和柠檬酸等6种,而接种G.m的则检测到草酸、酒石酸、苹果酸、乳酸、乙酸、柠檬酸、丁二酸等7种,G.v处理的检测到酒石酸,接种处理均未检测到顺丁烯二酸;接种丛枝菌根真菌增加了枳根系分泌有机酸的量(比未接种处理增加19.80~56.87 mg/kg,且施用AlPO₄后有机酸含量显著增加(增加20.06~21.84 mg/kg);未接种植株根系仅分泌少量有机酸;接种植株根系分泌的有机酸以苹果酸(42.87%)、柠檬酸(39.22%)和草酸(12.06%)为主。

关键词: 丛枝菌根真菌, 枳实生苗, 根系, 低磷胁迫, 难溶性磷酸盐, 有机酸