We examined the effects of nitrogen, soil microbe and their interactions on biomass allocation, growth and photosynthesis of Fraxinus mandschurica, a typical tree species in Changbai Mountain, through outdoor control experiments. In June 2017, an experiment with two-factor randomized block design was carried out. There were four treatments: control (F), nitrogen addition (FN), sterilization (FS), sterilization and nitrogen addition (FSN), six repetitive blocks, three repetitions per block, including 18 repetitions of each treatment. In mid-August 2018, we measured photosynthetic parameters and then harvested seedlings to measure biomass and growth parameters in September. The results showed that compared with F, FN significantly increased total biomass by 14%, basal diameter by 9%, chlorophyll content, net photosynthetic rate (Pn), stomatal conduc-tance (gs), transpiration rate (Tr) by 75%, 318%, 231%, 227% respectively. FS significantly increased total biomass by 13%, basal diameter by 9% and chlorophyll content, Pn, gs and Tr increased by 34%, 213%, 120% and 115%, respectively. FSN increased total biomass by 23%, basal diameter by 14%, chlorophyll content, Pn, gs and Tr increased by 81%, 672%, 312% and 273%, respectively. Nitrogen, soil microbe and their interactions had significant effects on biomass, growth and photosynthesis of F. mandschurica seedlings. Soil microbe would regulate the response of F. mandschurica seedlings to nitrogen.
以长白山地区典型树种——水曲柳为研究对象,通过室外控制试验,分析了氮、微生物及其相互作用对水曲柳幼苗生物量分配、生长和光合作用的影响.于2017年6月采用二因素随机区组设计试验,共4个处理:对照(F)、加氮(FN)、灭菌(FS)、灭菌加氮(FSN),6个重复区组,每个区组内每处理3个重复,即每个处理有18株幼苗.2018年8月中旬进行光合指标的测定,并于同年9月初收获植物,测量生物量及生长指标.结果表明: 与F相比,FN使水曲柳幼苗的总干质量显著提高14%,基径提高9%,叶绿素含量、净光合速率(Pn)、气孔导度(gs)、蒸腾速率(Tr)分别显著提高75%、318%、231%、227%;FS使总干质量显著提高12%,基径提高9%,叶绿素含量、Pn、gs、Tr分别显著提高34%、213%、120%、115%;FSN使总干质量显著提高23%,基径提高14%,叶绿素含量、Pn、gs、Tr分别显著提高81%、672%、312%、273%.氮、土壤微生物及其交互作用对水曲柳幼苗的生物量、生长和光合作用有着显著作用,土壤微生物在一定程度上调控了水曲柳幼苗对氮的响应.
Keywords: Fraxinus mandschurica; biomass; growth; nitrogen; photosynthesis; soil microbe.