Effect of simulated nitrogen deposition and inoculation with arbuscular mycorrhizal fungi on growth and photosynthesis of Cunninghamia lanceolata seedlings
[Objective]The regulation of root symbiotic fungi of Cunninghamia lanceolata in response to nitrogen(N)deposition was investigated to provide reference for enhancing the productivity of C.lanceolata plantations in the context of elevated global N deposition.[Method]A factorial experiment design,which included 3 levels of simulated nitrogen(N)deposition(N0 for 0 kg·hm-2·a-1,low N30 for 30 kg·hm-2·a-1 and high N60 for 60 kg·hm-2·a-1)and 3 inoculation treatments(no inoculation,inoculation with Glomus intradices,and inoculation with G.mosseae),was conducted on potted C.lanceolata seedlings in greenhouse,to study the effect of inoculating arbuscular mycorrhizal fungi(AMF)on the growth and photosynthesis of C.lanceolata under simulated N deposition.[Result]Both types of AMF led to high infection rates on C.lanceolata roots under simulated N depo-sition,and N simulation at low level and inoculation with AMF improved the growth of seedlings,with greater promotive effect being from G.mosseae.Under high simulated N deposition,the underground biomass of seedlings was decreased,while the accumulation of aboveground biomass and total biomass were significantly increased after inoculation with G.mosseae(P＜0.05).The root-shoot ratio followed a downtrend under simulated N deposition,while was mitigated after the inoculation with AMF,and the variations in root-shoot ratio were not significant in the interaction groups(P＞0.05).Under simulated N deposition,AMF inoculation significantly im-proved the chlorophyll content,leaf color value,net photosynthetic rate,stomatal conductance and electron transport rate(P＜0.05),and the combination of low N deposition and AMF inoculation led to the highest net photosynthetic rate and chlorophyll content of C.lanceolata.[Conclusion]AMF can effectively infect the roots of C.lanceolata,which resulted in improved seedling growth at simulated N deposition,with the optimum promotive effect coming from G.mosseae;AMF inoculation also mitigates the ad-verse effect of high N deposition on plants,and increases photosynthesis overall.
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