AM真菌影响入侵植物黄顶菊与本土物种狗尾草竞争生长的机理研究

该研究以入侵植物黄顶菊Flaveria bidentis(L.)Kunt]和本土伴生植物狗尾草为材料,通过筛选出黄顶菊单一优势群落AM真菌,于温室盆栽条件下,采用2物种单播、混播以及接种AM真菌和不接种共6个处理,分析AM真菌对黄顶菊和狗尾草的根系侵染率、相对竞争强度、植株氮磷钾光合利用率、以及丙二醛含量和保护酶活性的影响,探讨AM真菌对黄顶菊与狗尾草竞争生长的机理。结果显示:(1)黄顶菊根际土壤AM真菌共包括4属10种,其中优势种为Glomus constrictum、Glomus perpusillum、Glomus reticulatum;盆栽接种AM真菌后,黄顶菊的根系侵染率显著高于本土伴生植物狗尾草,但接种AM真菌后黄顶菊相对竞争强度显著降低了29.57%,却对狗尾草相对竞争强度无显著影响。(2)接种AM真菌使黄顶菊植株光合氮、磷、钾利用率显著升高,但对伴生植物狗尾草的光合氮、磷、钾利用率均无显著影响。(3)接种AM真菌对黄顶菊植株POD和CAT活性以及MDA含量无显著影响,但显著增加了SOD和APX活性,而伴对生植物狗尾草的POD、CAT和APX活性均显著降低,MDA含量显著提高。研究表明,AM真菌对黄顶菊和狗尾草具有不同的选择性,AM真菌的定植促进了黄顶菊的竞争生长,增加了植株N、P含量、光合养分利用率以及抗氧化酶活性;但显著降低了本土伴生植物狗尾草的N、P吸收以及抗氧化酶活性。因此,AM真菌在竞争生长中对黄顶菊产生了偏利反馈,有助于黄顶菊的入侵。

Mechanism of AM Fungi on Competitive Growth between Invasive Plant Flaveria bidentis and Native Plant Setaria viridis

Flaveria bidentis was an invasive plant and Setaria viridis was its associated native plant species.The arbuscular mycorrhizal fungi gathered in the rhizosphere soil of F.bidentis during its invasion was selected.And then the effect of AM fungi on the root colonization rate,relative competition intensity,rhotosynthetic nutrient use efficiency,malonaldehyde content and antioxidant enzyme activities of F.bidentis and S.viridis were carried out in greenhouse pot.In the experiment there were 3 treatments:monoculture and mixture treatment of the two species,and each treatment including two levels:AM fungal inoculated and no AM fungi inoculated.The results showed that:(1)there were 4 genera and 10 species AM fungi in the rhizosphere soil of F.bidentis.Among them Glomus constrictum,Glomus perpusillum,Glomus reticulatum were the dominant species.The root colonization rate of F.bidentis was significantly higher than that of S.viridis.The relative competition intensity of F.bidentis was significantly reduced 29.57% after it was inoculated with AM fungi,while competition had no significant effect on S.viridis.(2)The AM fungi increased the nitrogen,phosphorus,photosynthetic nutrient use efficiency of F.bidentis,and then promoted the competitive growth of F.bidentis,while it had no significant effect on the growth of S.viridis.(3)The AM fungi has no significant effect on POD,CAT activities and MDA content of F.bidentis.The AM fungi significantly increased the activities of SOD and APX and the content of MDA,while the activities of POD,CAT and APX of S.viridis were significantly decreased.The results showed that AM fungi had different selectivity between F.bidentis and S.viridis.The colonization of AM fungi promoted the competitive growth of F.bidentis,increased the absorption of nitrogen and phosphorus,photosynthetic nutrient use efficiency,enhanced the activities of antioxidant enzymes in leaves and reduced the content of malondialdehyde of F.bidentis.AM fungi reduced the absorption of phosphorus,photosynthetic nutrient use efficiency and antioxidant enzyme activities of S.viridis.Thus the AM fungi produced laterality feedback on F.bidentis than S.viridis,which promoted the invasion of F.bidentis.