中文摘要：

以喜树幼苗为试材,通过温室盆栽接种试验,研究了蜜色无梗囊霉（Acaulospora mellea）不同接种时期对喜树幼苗叶片光合特性的影响。结果表明：丛枝菌根的形成有助于提高喜树幼苗叶片的光合色素含量、净光合速率、气孔导度和蒸腾速率,但其促进作用受到接种时期的影响,伴随着接种时期的延后,菌根真菌对喜树幼苗的促进作用减弱。长出真叶后第0天和20天接种菌根真菌对喜树幼苗的促进作用明显,尤其是第0天接种的菌根幼苗,其叶绿素a、b和总叶绿素含量以及净光合速率、气孔导度和蒸腾速率均为最高,与无菌根幼苗差异显著。并且,长出真叶后第0天接种的菌根幼苗有效量子产量（EQY）和光化学淬灭（qP）也显著高于无菌根幼苗。长出真叶后第20天接种的菌根幼苗叶绿素a/b、类胡萝卜素含量和PSⅡ最大光化学量子产量（Fv/Fm）最高。长出真叶后超过20d以上接种（40、60、80d）的菌根幼苗叶绿素含量、净光合速率、Fv/Fm高于或接近无菌根幼苗,促进作用有限。

英文摘要：

Taking Camptotheca acuminata seedlings as material,the effect of different inoculation time on the photosynthesis of Camptotheca acuminata seedlings with arbuscular mycorrhizal fungi（AMF）in the greenhouse were studied.The results showed that AM formation was contributed to enhancement of the photosynthetic pigment content,net photosynthetic rate（Pn）,stomatal conductance（Gs）and transpiration rate（Tr）in leaves of C.acuminataseedlings.But the promoting effect of AMF was got by different inoculation time,and weakened with the delay of inoculation time.The photosynthesis of seedlings inoculated with Acaulospora mellea at 0day and 20days after grow true leaf was obviously promoted.The chlorophyll a content,chlorophyll b content,total chlorophyll content,Pn,Gs and Tr of seedlings inoculated with A.melleaat 0day after grow true leaf were the highest,and which was remarkable higher than nonmycorrhizal seedlings.Also the effective quantum yield（EQY）and photochemical quenching（qP）was significantly higher than non-mycorrhizal seedlings.The chlorophyll a/b,carotenoid content and maximal photochemical efficiency of PSII in the dark（Fv/Fm）of seedlings inoculated with A.melleaat 20days after grow true leaf were the highest.The photosynthetic pigment content,Pn and Fv/Fm of seedlings inoculated with A.melleaover 20days after grow true leaf,which including the 40days,60days and 80days were higher than or closed to non-mycorrhizal seedlings.And the promoting effect was very limited.