不同根系分泌物对土壤N2O排放及同位素特征值的影响  

Effects of Different Root Exudates on Soil N2O Emissions and Isotopic Signature

作　　者：庄姗 林伟[1] 丁军军[1] 郑欠 寇馨月 李巧珍[1] 李玉中[1,2] ZHUANG Shan;LIN Wei;DING JunJun;ZHENG Qian;KOU XinYue;LI QiaoZhen;LI YuZhong(Institute of Environment and Sustainable Development in Agriculture,Chinese Academy of Agricultural Sciences/Key Laboratory of Dryland Farming Agriculture,Ministry of Agriculture and Rural Affairs,Beijing 100081;Environmental Stable Isotope Laboratory,Chinese Academy of Agricultural Sciences,Beijing 100081)

机构地区：[1]中国农业科学院农业环境与可持续发展研究所/农业农村部旱地节水农业重点实验室,北京100081 [2]中国农业科学院环境稳定同位素实验室,北京100081

出　　处：《中国农业科学》2020年第9期1860-1873,共14页Scientia Agricultura Sinica

基　　金：国家自然科学基金(41473004,41701308);国家重点研发计划项目(2017YFD0201702)。

摘　　要：【目的】探究植物根系分泌的主要组分(有机酸、氨基酸、糖类)对土壤N2O排放及其微生物过程的影响,为选择适宜的植物进而控制土壤N2O排放提供支撑。【方法】通过室内试验分别添加草酸、丝氨酸、葡萄糖于土壤中模拟根系的3种主要分泌物,每种分泌物设置两个浓度水平:低浓度(150μg C·d^-1)和高浓度(300μg C·d^-1),另设置添加蒸馏水的对照组,共7个处理。将土壤置于120 mL玻璃瓶中进行培养,24 h内采集气体样品7次,每次培养2 h,获取N2O排放速率、日累积排放量和同位素特征值(δ^15N^bulk、δ^18O和SP(site preference,SP=δ^15N^α-δ^15Nβ))。【结果】添加3种根系分泌物组分后,土壤N2O排放速率均逐渐升高,且均高于对照。高浓度处理组N2O累积排放量为:葡萄糖((3.2±1.3)mg·kg^-1·d^-1)处理>丝氨酸((2.6±0.5)mg·kg^-1·d^-1)处理>草酸((1.4±0.2)mg·kg^-1·d^-1)处理,低浓度处理组为:草酸((2.7±1.3)mg·kg^-1·d^-1)处理>丝氨酸((1.8±0.4)mg·kg^-1·d^-1)处理>葡萄糖((1.6±0.8)mg·kg^-1·d^-1)处理;添加根系分泌物的不同处理间土壤N2O的δ18O值无明显差异,并稳定在24.1‰—25.6‰,且均显著高于对照((20.1±1.5)‰);土壤N2O的δ15Nbulk值与添加根系分泌物的种类有关,其中草酸处理组为(-20.06±2.22)‰、丝氨酸处理组为(-22.33±1.10)‰、葡萄糖处理组为(-13.86±1.11)‰、对照组为(-23.14±3.72)‰。各处理土壤N2O的SP值的变化范围为13.13‰—15.03‰,根系分泌物浓度越高,SP值越低。综合分析不同处理4个指标(N2O排放速率、N2O的δ^15N^bulk、δ^18O和SP值)的不同时刻的检测值与日均值的校正系数,添加根系分泌物后第16小时各处理4个指标的校正系数最接近于1。【结论】在NH4^+-300 mg N·kg^-1的土壤环境下根系分泌物促进N2O的排放,且在培养期间(24 h)土壤N2O排放速率逐渐升高。高浓度处理组葡萄糖对土壤N2O排放速率促进效果最强,低浓度处理组草【Objective】The aim of this study was to investigate the effects of the main plant root exudates(organic acids,amino acids,sugars)on N2O emission and its microbial processes,so as to provide a support for selecting suitable plants to control soil N2O emissions.【Method】Three main components of root exudates,including oxalic acid,serine and glucose,were added in the soil,and two levels of concentration were set for each component:low concentration(150μg C·d^-1)and high concentration(300μg C·d^-1).There were totally 7 treatments with a control treatment treated with distilled water,and all treatments were incubated in 120 mL glass bottles in incubator.The gas samples were sampled 7 times within 24 hours after 2-hour incubation each time.After sampling,the N2O emission rate,daily cumulative emission and isotope signatures(δ^15N^bulk,δ^18O and SP(intramolecular 15N site preference,δ^15N^α-δ^15Nβ))were measured,then the optimal sampling time was determined according to their daily variation rules.【Result】The N2O emission rate of soils increased gradually after adding three components of root exudates,which were higher than the control treatment.The cumulative emission of N2O in the high concentration treatment was:Glucose treatments((3.2±1.3)mg·kg^-1·d^-1)>Serine treatments((2.6±0.5)mg·kg^-1·d^-1)>Oxalic acid treatments((1.4±0.2)mg·kg^-1·d^-1),low concentration treatment:Oxalic acid((2.7±1.3)mg·kg^-1·d^-1)>Serine((1.8±0.4)mg·kg^-1·d^-1)>Glucose((1.6±0.8)mg·kg^-1·d^-1);the values ofδ18O of N2O were not different among different root exudate treatments and were stable at 24.1‰-25.6‰,but significantly higher than the control treatment((20.1±1.5)‰);theδ15Nbulk value of N2O was related to the component of root exudates added,which was(-20.06±2.22)‰ of oxalic acid treatment,(-22.33±1.10)‰ of serine treatment,(-13.86±1.11)‰ treated of glucose treatment,and(-23.14±3.72)‰ of the control treatment.The SP value of N2O of each treatment ranged from 13.13‰ to 15.03‰,an

关 键 词：根系分泌物 硝化作用 反硝化作用 N2O 同位素特征值 

分 类 号：S154.1[农业科学—土壤学]