不同供水下白羊草(Bothriochloa ischaemum)离体根呼吸特征——基于稳定碳同位素示踪技术  

Excised root respiration of Bothriochloa ischaemum under different water supply conditions,measured using stable carbon isotope techniques

作　　者：刘琦[1] 李鹏[1] 刘莹[1] 肖列[1] 黄鹏 汤珊珊[1] LIU Qi,LI Peng,LIU Ying,XIAO Lie,HUANG Peng,TANG Shanshan(State Key Laboratory Base of Eco-hydraulic in Arid Area, Xi＇an University of Technology, Xi＇an 710048, Chin)

机构地区：[1]西安理工大学陕西省西北旱区生态水利工程国家重点实验室培育基地,西安710048

出　　处：《生态学报》2018年第9期3035-3045,共11页Acta Ecologica Sinica

基　　金：国家重点研发计划(2016YFC0402404);国家自然科学基金重点项目(41330858);校级基金(310-252071506;310-252071505)

摘　　要：植物根呼吸是土壤呼吸的主要组成,研究根呼吸对生态系统碳收支及碳平衡有重要意义。采用^(13)C脉冲标记技术,在3种供水条件下,对比不同根离体时间(标记后0,6,24,48,216,360 h)的白羊草离体根呼吸速率和根呼吸释放的δ^(13)C同位素比值变化,分析根参数与离体根呼吸相关性。结果表明:1)不同离体时间的离体根呼吸速率变化趋势一致,3种供水条件下无显著差异,均在0—20 min急剧下降,下降范围为32%—39%。2)测定离体根呼吸释放的δ^(13)C在不同离体时间的变化,为实时监测转移到白羊草根系的^(13)CO_2在根部释放的过程提供了新思路;不同离体时间,3种供水条件下根呼吸释放的δ^(13)C在2 h内均值大小呈:供水充分>轻度胁迫>重度胁迫。随离体时间(0—360 h)推移根呼吸释放的δ^(13)C均值先增大后减小,在216 h达到峰值31.46‰;3)离体根呼吸速率和根呼吸释放的δ^(13)C受根系根面积、比根面积、N含量、C/N及根组织δ^(13)C的影响显著。4)轻度水分胁迫可促使根系生长(C固定)和根呼吸(C代谢)同时增加。Plant root respiration is a primary component of soil respiration. In-depth research on plant root respiration is of great importance in understanding the budget and balance of ecosystem carbon storage. The present study used ^13C pulselabeling technology to evaluate changes in excised root respiration rates and root δ^13C isotopic values of Bothriochloa ischaemum after different excision times（ 0 h,6 h,24 h,48 h,216 h,and 360 h after labeling） and analyzed the relationships between plant root parameters and excised root respiration. The results showed that： 1） Excised root respiration did not significantly differ after different excision times under three water supply conditions. Excised root respiration declined sharply by 32%—39% after the first 20 minutes. 2） Determination of the changes in δ^13C isotope ratios in excised roots after different excision times provided us information on how the δ^13C isotopes ratio changed in the roots of B. ischaemum. The mean value of the δ^13C isotope ratio after the first 2 h was greatest in the well-watered condition,intermediate under moderate drought stress,and least under severe drought stress. The mean values of δ^13C isotope ratiosfirst increased and then decreased during the entire period of 0—360 h,with the highest value of 31.46‰ at 216 h. 3） The excised root respiration rate and the δ^13C isotope ratio were significantly influenced by root area,specific root area,N concentration,C/N ratio,and δ^13C of root tissue. 4） Moderate drought stress contributed to a simultaneous increase in the root growth rate（ C fixation） and root respiration（ C metabolic rate）.

关 键 词：白羊草 供水条件 ^13C脉冲标记 离体根呼吸速率 根呼吸释放的δ^13C 

分 类 号：Q945[生物学—植物学]