摘要
利用同位素示踪和热扩散技术研究了不同胁迫处理栓皮栎的水分运输和储存差异。结果表明,注射氘同位素后,充分灌溉、轻度和重度胁迫处理的最大氘同位素比率分别升高到586.67‰、997.33‰和1364.89‰,处理间差异显著。轻度和重度胁迫处理的示踪速率分别为0.10 m/h和0.07 m/h,显著低于充分灌溉处理,但半减期和残留期显著高于充分灌溉。轻度和重度胁迫处理的枝条栓塞程度(PLC)比充分灌溉显著增加,液流通量、水势和蒸腾速率则显著减小。统计分析表明蒸腾作用强弱决定树体水分运输速率,PLC的增加和枝条水势的降低阻碍木质部水分运输。半减期和残留期内,轻度和重度胁迫处理的累积液流量显著高于充分灌水处理,运载相同体积的示踪剂,胁迫处理栓皮栎需要的水量增加,表明胁迫环境下受到PLC、蒸腾以及与树体储水交换的影响,水分运输效率下降。栓皮栎通过栓塞和储水交换来降低水分运输速率和效率,调控水分的收支平衡来适应干旱的环境。
Trees,especially big ones,have huge and complicated vascular systems which make the long-distance water transport difficult to study.We used the heat dissipation method and deuterated water as tracers to characterize water transport and storage properties of Quercus variabilis trees under the different water stress treatment.The transit time for D2O transport from the trunk base to the upper branches and the tracer residence time were determined by measuring hydrogen isotope ratios in water extracted from branches sampled in regular intervals.The result indicated that the maxima δD of full irrigation（FI）,mild water stress（LWS） and severe water stress（SWS） respectively increased to 586.67‰、997.33‰ and 1364.89‰ after injecting deuterium tracer.There were significant differences in maxima δD among the three treatments.The tracer velocities with LWS and SWS were significantly lower than FI treatment but the tracer half-life and residence time were longer than FI treatment.The branch PLC,sapflow rate,water potential and transpiration rate were also observed.The branch PLC treated with LWS and SWS was significantly higher than FI treatment and the sapflow rate,water potential and transpiration rate were lower.There significantly positive correlations between tracer velocity and leaf transpiration rate（P〈0.01,n=27）,and between tracer velocity and sapflow rate（P〈0.01,n=9）.The results indicated that water transport was determined by transpiration rate.The PLC and branch water potential were inversely correlated with tracer velocity（P〈0.01,n=27）,suggesting that drought stress-induced embolism and lower water potential should increase resistance to water transport.Tracer half-life and residence time increased as water stress increased.Tracer half-life and residence time were significant exponential functions with the branch PLC（P〈0.01,n=27）,but power functions with the leaf transpiration rate.The times needed for transporting the same volume tracer were increased,indicating that
出处
《生态学报》
CAS
CSCD
北大核心
2012年第12期3892-3901,共10页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(31000182)
林业公益性行业科研专项课题(201104009-04)
关键词
栓皮栎
稳定同位素
示踪速率
栓塞
蒸腾
Quercus variabilis
stable isotope
tracer velocity
embolism
transpiration
