稳定同位素在植物水分来源及利用效率研究中的应用

Application of Stable Isotope Techniques in the Study of Plant Water Sources and Use Efficiency

介绍了稳定氢、氧、碳同位素技术在定量区分植物水分来源及利用效率研究中的应用。以往大量研究结果表明,由于植物根系在吸收水分过程中没有发生同位素分馏,所以通过比较和分析植物木质部水分及其可利用水源的氢氧同位素δ值,就可以定量判断植物的水源;植物在光合作用过程中会产生碳同位素的分馏,从而使得植物叶片中的碳同位素组成能够成为指示植物水分利用效率的一个间接指标,是目前研究植物叶片长期水分利用效率的最佳方法;稳定同位素技术作为安全的示踪剂,有助于人类了解植物的生理生态功能,随着该技术的不断完善和研究的不断深入,同位素技术将会在生态学研究的许多领域得到广泛的应用。

This paper described the application of stable hydrogen,carbon and oxygen isotopes techniques in tracing sources of plant water and water use efficiency.Since the process that plant roots uptake water is non-frac-tionating,plant xylem water has the same composition of stable hydrogen and oxygen isotopes as soil water utilized by the plant.By analyzing the composition of hydrogen and oxygen isotopes of plant xylem water and potential sources of water,we could quantitatively determine the contributions of the sources to plants.For the study of water use efficiency,there were many researches showed that the composition of stable carbon isotopes of leaves can be an indirect indicator of plant water use efficiency.Photosynthesis is one of the most significant processes of carbon iso-tope fractionation in nature.So,stable carbon isotopes techniques had become the best way to study the long-term water use efficiency of plant leaves presently.As a safe tracer material,stable isotopes technique will help people to understand the plant’s ecophysiological process.Anyway,with the continuous improvement of techniques,sta-ble isotope techniques will be widely used in many areas of ecology.