铵硝比对亚热带树种幼苗氮吸收偏好及吸收根属性的影响  

Effects of Different Ammonium to Nitrate Ratios on Nitrogen Uptake Preference and Traits of Absorptive Roots of Subtropical Trees Seedlings

作　　者：刘倩愿 陈奕帆 陈艳梅[1] 王辉民[2] Liu Qianyuan;Chen Yifan;Chen Yanmei;Wang Huimin(School of Geographical Sciences,Hebei Key Laboratory of Environmental Change and Ecological Construction,Hebei Normal University ,Shijiazhuang 050024;Qianyanzhou Ecological Research Station,Key Laboratory of Ecosystem Network Observation and Modeling,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences ,Beijing 100101;Industry Development and Planning Institute,National Forestry and Grassland Administration ,Beijing 100010)

机构地区：[1]河北师范大学地理科学学院河北省环境演变与生态建设实验室,石家庄050024 [2]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室千烟洲生态站,北京100101 [3]国家林业和草原局产业发展规划院,北京100010

出　　处：《林业科学》2023年第2期48-57,共10页Scientia Silvae Sinicae

基　　金：河北省自然科学基金项目(D2021205006);河北省高等学校科学技术研究项目(QN2021092);国家自然科学基金项目(31730014);河北师范大学科研基金资助项目(L2021B24)。

摘　　要：【目的】明确不同铵硝比对亚热带针、阔叶树苗的氮素吸收偏好及吸收根属性的影响,为阐明人工林养分获取策略与土壤氮循环提供理论依据。【方法】以亚热带常见树种湿地松、马尾松、深山含笑和枫香的2年生幼苗为对象,设置3种铵硝比(15∶1、8∶8和1∶15)进行沙培试验,利用15N同位素示踪技术测定植物的无机氮吸收速率,分析其与吸收根形态、构型属性的相关性。【结果】1) 4个树种幼苗的无机氮吸收速率具有环境可塑性,当铵氮(NH_(4)^(+)-N)占优势时,4个树种均偏好吸收铵氮;当硝氮(NO_(3)^(-)-N)占优势时则偏好吸收硝氮。当铵硝比为8∶8时,则表现出树种对不同形态N吸收的差异:针叶树种的NO_(3)^(-)-N吸收速率是NH_(4)^(+)-N的2倍多,但阔叶树种之间没有显著差异。2)铵硝比对植物吸收根的比根长和比表面积有显著影响,对直径、组织密度、分支比和分支呈强度无显著影响。3) 4种树种幼苗的无机氮吸收速率与根分支呈显著正相关,与各器官生物量呈显著负相关。【结论】4个树种幼苗对不同形态N的吸收依赖于底物N可利用性和物种特异性。环境中铵硝比变化时,湿地松和马尾松根系可通过生理-形态属性的权衡特性获取养分,无机氮吸收速率降低,比根长增大(直径变小);阔叶树深山含笑和枫香通过加强吸收根形态属性(增大比根长和比表面积)、构型属性(增大分支比)和生理属性(提高NH_(4)^(+)-N吸收速率)获取养分。各树种不同的养分获取策略可促使其更好地适应环境变化。【Objective】This study aims to clarify the effects of different ammonium to nitrate ratios on nitrogen(N)uptake preference and traits of absorptive roots of coniferous and broadleaf seedlings,so as to provide scientific basis for understanding nutrient acquisition and soil N cycle in subtropical plantations.【Method】Two-year-old seedlings of common subtropical tree species,including Pinus elliottii,Pinus massoniana,Michelia maudiae,and Liquidambar formosana,were cultured in sands with addition of three different ammonium to nitrate ratios(15∶1,8∶8,and 1∶15).The inorganic N uptake rates of plants were measured by using the 15N isotope tracer technique,and the correlations between the inorganic N uptake rates and the morphological and architectural traits of absorptive roots were analyzed.【Result】1)The inorganic N uptake rates of the seedlings of the four species varied under environments with different ammonium to nitrate ratios.The four species preferred to absorb NH _(4)^(+)-N when ammonium was dominant in the sand culture,but preferred to absorb NO_(3)^(-)-N when nitrate was dominant.However,species showed different N uptake when the ratio of ammonium to nitrate was 8∶8.The coniferous species absorbed NO3−-N at a rate more than twice that of NH_(4)^(+)-N,but there was no significant difference in the uptake of the two forms of nitrogen by broadleaved species.2)Ammonium-nitrate ratio had a significant impact on root specific length and specific surface area,but had no effect on diameter,tissue density,branching ratio and branching intensity.3)The inorganic N uptake rate of the four species seedlings was significantly positively correlated with root branches,and significantly negatively correlated with organ biomass.【Conclusion】The N uptake rate of seedlings of four tree species depends on substrate N availability and species specificity in response to contrasting edaphic environment.The two coniferous species obtain nutrients through the trade off between physiology(decreased N uptake rat

关 键 词：氮素吸收速率 吸收根 形态属性 铵硝比 

分 类 号：S718.43[农业科学—林学]