群众杨幼苗叶光合特性与碳氮...O_2浓度和气温升高的响应_王卫锋.pdf

doi：10.11707/j.1001-7488.LYKX20200897群众杨幼苗叶光合特性与碳氮分配对 CO2浓度和气温升高的响应王卫锋1赵瑜琦1高苗琴1宗毓铮2郝兴宇2（1.山西农业大学林学院晋中 030801；2.山西农业大学农学院晋中 030801）摘要：【目的】研究杨树光合作用和碳氮分配对 CO2浓度和温度升高的响应，探讨气候变化下杨树的生理生态适应机制，以期为我国北方杨树人工林生产力和生态效益的长期提升提供理论依据。【方法】以盆栽群众杨当年生扦插幼苗为试验材料，在开顶式生长室内模拟研究了空气 CO2浓度和气温升高(分别比室外大气升高 200 mol mol1和2)及其共同作用下的功能叶光合特性、叶解剖结构、器官间干物质和碳氮分配的响应，并探讨了苗期群众杨对 CO2浓度和气温升高的生理生态响应。【结果】1)在 CO2浓度升高处理下，群众杨叶片气孔密度降低，蒸腾速率减弱，瞬时水分利用效率显著提高；光合潜力和氮利用效率增加，并通过叶肉组织增厚、叶和根碳氮比增加、比叶重增大以及根冠比增加等途径维持单位叶面积氮含量、瞬时光合特性和叶绿素荧光特性不变，而单位质量暗呼吸速率降低，并使单株总干质量和总碳量显著增加。2)增温 2 下的群众杨叶气孔密度显著增加，但瞬时气体交换和荧光参数、光合特性变化不显著，株高和单株总氮量略低，器官间的干物质和碳氮分配变化亦不明显。3)在同时提高 CO2浓度和气温处理下，根碳氮比显著低于 CO2浓度升高处理，而光合氮利用效率显著增加，但整体而言 CO2浓度升高和增温并未表现出明显的协同效应。4)在 CO2浓度升高、增温以及同时提高 CO2浓度和气温处理下，群众杨茎干物质比例均显著降低，茎碳氮比不变，根干物质比例和碳氮比响应比茎和叶更敏感。【结论】群众杨幼苗可通过调控叶片形态结构和增大根系碳分配维持叶片光合固碳能力，以适应空气 CO2浓度升高导致的氮浓度降低；增温 2 对群众杨光合特性、植株生长和碳氮分配影响不明显；CO2浓度升高和增温之间没有明显的协同作用。关键词：二氧化碳浓度；温度；杨树；光合特性；碳氮分配中图分类号：S718.43文献标识码：A文章编号：10017488(2023)02004008Leaf Photosynthesis and Carbon and Nitrogen Distribution of Populuspopularis 35-44 YoungCuttings in Response to Elevated CO2 Concentration and TemperatureWang Weifeng1Zhao Yuqi1Gao Miaoqin1Zong Yuzheng2Hao Xingyu2（1.College of Forestry,Shanxi Agricultural UniversityJinzhong 030801；2.College of Agriculture,Shanxi Agricultural UniversityJinzhong 030801）Abstract：【Objective】In this study,we investigated the response processes of leaf photosynthesis and carbon and nitrogendistribution of a poplar under elevated atmosphere CO2 concentration and temperature,and explored the ecophysiologicalacclimation mechanism of the poplar to global climate changes,which would provide theoretical basis for promoting the long-termproductivity and ecological benefits of poplar plantations in northern China.【Method】The potted annual cuttings of a hybridpoplar(Populus popularis 35-44)were subjected to elevated CO2(+200 molmol1)and/or temperature(+2)in OTCs for 4months,and the changes of leaf photosynthetic traits,anatomical and stomatal traits,drymass and carbon and nitrogen distributionamong organs were investigated.The ecophysiological responses of P.popularis 35-44 seedlings to elevated CO2 concentrationand temperature were discussed.【Result】1)Under elevated CO2 concentration conditions,leaf stomatal density decreasedand transpiration rate decreased,resulting in an increase of instantaneous water use efficiency.Leaf photosynthetic capacity andnitrogen use efficiency significantly increased.Nitrogen content per unit leaf area,instantaneous photosynthetic characteristics,andchlorophyll fluorescence characteristics remained unchanged through thickening leaf mesophyll,increasing root shoot ratio,CNratio in leaves and roots,and LMA.However,the dark respiration rate per drymass decreased,and whole-plant drymass and total 收稿日期：20201111；修回日期：20210607。基金项目：国家自然科学基金青年基金项目(31400527);山西省应用基础研究项目(201701D221190);山西农业大学青年拔尖创新人才支持计划(BJRC201602);黄土高原特色作物优质高效生产省部共建协同创新中心基金项目(SBGJXTZX-27)。第 59 卷 第 2 期林业科学 Vol.59，No.22 0 2 3 年 2 月SCIENTIA SILVAE SINICAEFeb.，2 0 2 3carbon content significantly increased.2)Under the elevated temperature condition by 2,leaf stomatal density significantlyincreased,but instantaneous gas exchanges,chlorophyll fluorescence parameters and photosynthetic traits did not change.Plantheight and whole-plant nitrogen slightly decreased,but organ drymass,carbon and nitrogen distribution maintained unchanged.3)Under the treatment of both elevated CO2 concentration and temperature,the carbon nitrogen ratio in roots was significantlylower than that of the treatment of increasing CO2 concentration,while the photosynthetic nitrogen utilization efficiency wassignificantly increased.However,the increase in CO2 concentration and temperature did not show an obvious synergistic effect.4)CO2 concentration and/or temperature treatments all decreased the stem drymass distribution percentage,but the stem CNratio remained unchanged.However the treatment significantly changed C:N ratio in leaves and roots.【Conclusion】P.popularis35-44 young cuttings can maintain leaf photosynthetic carbon fixation capacity by regulating leaf morphology,anatomyand C:N,which might be important under the declined nitrogen concentration induced by long-term elevated CO2.Elevatedtemperature does not sharply change leaf photosynthetic traits,growth and carbon and nitrogen distribution.Elevated air CO2concentration and temperature do not have synergistic effect to the poplar cuttings.Key words：CO2 concentration；temperature；poplar；photosynthetic traits；carbon and nitrogen distribution 杨树(Populus spp.)是我国北方地区人工林的主要造林树种，在保障区域生态安全以及木材战略储备中占据重要地位。未来全球大气 CO2浓度可达 538670 molmol1(IPCC,2013)，而 全 球 平 均 气 温 将 在2080 年比工业革命前升高 2(IPCC,2018)。植物对大气 CO2浓度、气温同时升高的响应决定了全球陆地生态系统的碳动态变化(彭静等,2016)。全球气候变化可能对该地区杨树人工林生态和经济效益产生严重 威胁(刘 世 荣 等,2018)。大 量 FACE(free air CO2enrichment)试验表明，CO2浓度升高可直接提高植物CO2同 化 速 率，降 低 气 孔 导 度、增 加 地 上 部 产 量(Battipaglia et al.,2013;Nowak et al.,2004)，并使得北方森林用水效率大幅提高(Keenan et al.,2013)。过去 50年间大气 CO2浓度不断升高，但基于树木年代学分析树木生长研究少有报道(Silva et al.,2013)，净光合速率的增长也远低于 Farq