植物碳同位素组成的环境影响因素及在水分利用效率中的应用

碳同位素值（δ13C）综合反映了植物光合作用过程中气孔的传导和CO2的固定，可以作为植物在环境中生理机能变化的指标，应用于研究植物生理与生态环境之间的关系。本文主要讨论植物碳同位素组成在不同环境中的变化，并对影响程度和机理进行了探讨。降水、温度、光照、土壤盐度、大气CO2浓度等不同程度影响植物的气孔传导和CO2的固定，植物的δ13C值相应产生不同的变化。降水因素对δ13C值影响最明显，温度对δ13C值产生的影响较复杂。一般情况下，大气中CO2都是通过影响植物叶片的内外压力，造成植物碳同位素值的差异。由于δ13C值不仅可以反映植物在光合作用过程中水分的利用，而且，δ13C值与水分利用效率具有正相关性，因此，碳同位素技术应用于植物生态研究中。

Effect of Environmental Factors on Stable Carbon Isotopic Composition of Plants and Application in Water Use Efficiency

Carbon isotopic composition (δ13C), which varies during the photosynthetic activity, can synthetically reflect both stomatal conductance and fixation of CO2. As physiological index of species in environment, δ13C can be used to study the relationship between plant and ecological environment. In this work, we mainly discussed the variations of carbon isotopic composition among distinct environmental factors. Furthermore, we talked about the influencing degree and mechanism. Easy to know that precipitation, temperature, irradiance, salinity of soil, CO2 concentration in atmosphere, etc influence, in different degree, the stomatal conductance and fixation of CO2, responding to change the δ13C value of plants. In these factors, precipitation is the most evident factor to the δ13C values, however, temperature is confound to reflect the δ13C values of plants. Atmospheric CO2 commonly influences the intercellular and ambient CO2 pressure of leaf, resulting to various δ13C values. The technique of carbon isotope can be used to study the ecology of plant, for δ13C values can not only reflect water use in the course of photosynthesis, but also the relationship between carbon isotopic composition and water use efficiency is corrective.