不同来源AM真菌对朱砂根生长和生理特征的影响

Effects of arbuscular mycorrhizal fungi from different sources on the growth and physiology of Ardisia crenata

朱砂根(Ardisia crenata)原产于东亚和东南亚地区,现已入侵美国南部等地区。为了探讨AM真菌对朱砂根入侵能力的影响,我们以根段接种的方法扩繁了源自入侵地美国德克萨斯州和原产地广东东莞、四川峨眉山和湖北兴山的朱砂根根系中的AM真菌,研究了这些不同来源的AM真菌对朱砂根生长和生理状况的影响。结果表明4个不同来源的AM真菌均能够提高朱砂根的叶面积比(LAR)和相对生长速率(RGR),而对其饱和净光合速率(Pn)、呼吸速率(Rd)、根冠比(R/S)和各器官中氮、磷营养元素含量均没有显著影响。四个不同来源的AM真菌对朱砂根的作用略有差异,其中入侵地德克萨斯州与原产地广东东莞AM真菌对朱砂根生长的促进作用较强,但入侵地AM真菌对朱砂根的促进作用并不普遍高于原产地,AM真菌的作用可能并不是导致入侵种群密度远高于本土种群密度的因素。

Ardisia crenata,a shrubby flowering plant native to East and Southeast Asia,is now invasive in southern USA and elsewhere.We used the trap culture method with A.crenata root fragments of as inocula to obtain host-associated arbuscular mycorrhizal（AM） fungi.AM fungi were obtained from the species＇ invasive range in Texas,USA,and its＇ native range in Dongguan in Guangdong Province,Emei Mountain in Sichuan Province and Xingshan in Hubei Province in China.The influences of these AM fungi from different sources on the growth and physiology of A.crenata were determined.Inoculation with all strains of AM fungi increased leaf area ratio（LAR） and relative growth rate（RGR）,but did not influence net photosynthetic rate at saturated light（Pn）,respiration rate（Rd）,ratio of root to shoot（R/S）,nitrogen and phosphorus concentration.There were some differences in the effects of AM fungi from different sources.AM fungi sourced from Dongguan in the native range and Texas in the invasive range had equal influence on A.crenata,being more stimulative than AM fungi from other sources.AM fungi sourced from the invasive range did not promote more growth of A.crenata than the combined AM fungi sourced from the native range.Therefore,we conclude that the effects of AM fungi may not be an important factor leading to higher density of A.crenata in invasive populations than in native populations.