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刘莹,李鹏,沈冰,冯朝红,刘琦,张祎.采用稳定碳同位素法分析白羊草在不同干旱胁迫下的水分利用效率.生态学报,2017,37(9):3055~3064 本文二维码信息
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采用稳定碳同位素法分析白羊草在不同干旱胁迫下的水分利用效率
Effects of drought stress on Bothriochloa ischaemum water-use efficiency based on stable carbon isotope
投稿时间:2016-01-18  最后修改时间:2016-10-12
DOI: 10.5846/stxb201601180112
关键词白羊草  稳定碳同位素  生物量  水分利用效率  干旱胁迫
Key WordsBothriochloa ischaemum  Stable carbon isotope  Biomass  Water-use efficiency  Drought stress
基金项目国家自然科学基金重点项目(41330858);国家自然科学基金(41471226,41271290);校级基金(310-252071506)
作者单位E-mail
刘莹 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  
李鹏 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 lipeng74@163.com 
沈冰 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  
冯朝红 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  
刘琦 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  
张祎 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  
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摘要:
本研究以黄土高原乡土草种白羊草(Bothriochloa ischaemum (L.)Keng.)为研究对象,采用盆栽控制实验,比较白羊草在3个水分处理(CK80%FC、MS60%FC和SS 40%FC)下的生物量积累和分配模式、瞬时水分利用效率(WUE)、不同部位(新叶、老叶、茎、细根、粗根)的稳定碳同位素组成(δ13C)和碳同位素分辨率(Δ13C)及其相互关系,以及干旱胁迫下影响水分利用效率的主导环境因子。结果表明:1)重度干旱胁迫显著降低植物整体生物量,显著增加根冠比和细根生物量比例;2)随着干旱胁迫加剧,白羊草各器官的δ13C均呈上升趋势,Δ13C呈减小趋势,SS处理不同器官δ13C和Δ13C没有显著差异,CK和MS处理的各器官δ13C均值表现分别为细根 > 粗根 > 老叶 > 新叶 > 茎、细根 > 新叶 > 老叶 > 粗根 > 茎,CK和MS处理Δ13C的值总体呈根 < 叶 < 茎。3)新叶的δ13CNLΔ13CNL与WUE的相关系数均最大,说明利用稳定碳同位素方法测定白羊草水分利用效率具有可行性。4)不同水分处理的WUE的主导影响因子不同,CK、MS、SS水分处理WUE分别受到叶面温度、大气水汽压亏缺和空气温度的影响最大。为采用稳定碳同位素方法指示白羊草水分利用效率可行性及阐明植物的胁迫响应机制提供理论依据。
Abstract:
Owing to low precipitation and high inter-annual variability, the Loess hilly and valley region experiences frequent drought, which significantly affects plant growth. Studying the response mechanism of plants to water stress is important with respect to improving water-use efficiency (WUE) in this arid and semi-arid area. In the present research, Bothriochloa ischaemum (L.) Keng., a typical native species in the Loess hilly-gully region, was selected to investigate biomass accumulation and allocation, instantaneous WUE, stable carbon isotope composition (δ13C), and stable carbon isotope discrimination (Δ13C) in different organs under three water regimes: control [CK, 80% field capacity (FC)], mild water stress (MS, 60% FC), and severe stress (SS, 40% FC). Photosynthetic parameters of B. ischaemum were measured at 09:00-11:00 on sunny windless days (Aug 3, 10, and 13,2014), using a portable photosynthesis determination system (Li-6400; Li-Cor, USA). On Nov 11, when the experiment ended, the new leaf, old leaf, stem, fine root, and coarse root parts of seedlings were sampled carefully and weighed (with accuracy 0.001 g) after drying at 65℃. The root-to-shoot ratio was then calculated as the ratio of the belowground dry biomass to aboveground dry biomass. The δ13C of different plant parts was measured using a CCIA-36d-EP Carbon isotope ratio mass spectrometer (Los Gatos Research, USA). The Δ13C of different plant parts was calculated based on δ13C and the carbon isotope ratio of atmospheric CO2. Many environmental factors that might affect WUE were analyzed to explore the response mechanisms of B. ischaemum under drought conditions. The following results were obtained. (1) The total biomass of B. ischaemum was significantly decreased under the SS condition, whereas the root-to-shoot ratio and fine root biomass were significantly increased under this water regime. (2) The δ13C and Δ13C in different plant parts showed different trends. Drought stress led to an increase in the δ13C value and decrease in the Δ13C value. There was no significant difference in the δ13C and Δ13C of different plant parts under the SS condition. The δ13C values under CK and MS conditions were in the order of fine root > coarse root > old leaf > new leaf > stem, and fine root > new leaf > old leaf > coarse root > stem, respectively. Furthermore, the Δ13C values under CK and MS conditions were all in the order of root < leaf δ13C and Δ13C values of new leaves had the highest correlation coefficients with respect to WUE, which indicated that the stable carbon isotope technique is suitable for the determination of the WUE of B. ischaemum. (4) The WUE was affected by different environmental factors under different water regimes. Leaf temperature, atmospheric water vapor pressure, and air temperature were the most important factors affecting WUE under CK, MS, and SS conditions, respectively. This research provides a theoretical basis for the feasibility of using the stable carbon isotope method to determine the WUE of B. ischaemum, and for elucidating the mechanism underlying the response of B. ischaemum to water stress.
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