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

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

碳同位素组成(δ(13C))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,用于研究植物生理与生态环境之间的关系。降水、温度、光照、土壤盐度、大气CO2浓度等因素都会在不同程度上影响植物叶片气孔传导和CO2的固定,导致植物的δ(13C)发生变化。降水因素对δ(13C)影响最明显,温度对δ(13C)产生的影响较复杂。一般情况下,大气中CO2通过影响植物叶片的内外压力,使植物δ(13C)发生变化。植物δ(13C)不仅可以反映光合作用过程中对水分的利用效率,而且与水分利用效率具有正相关性,因此,碳同位素技术在植物水分利用效率的研究中具有理论和现实意义。

Carbon isotopic composition δ（^13C）, which varies during the photosynthetic activity, can synthetically reflect both stomatal conductance and fixation of CO2. As physiological index of species in environment, δ（^13C） can be used to study the relationship be- tween plant and ecological environment. The variations of carbon isotopic composition a- mong distinct environmental factors were discussed . Furthermore, the influencing degree and mechanism were talked. Factors like precipitation, temperature, irradiance, salinity of soil, CO2 concentration in atmosphere, etc influence, in different degrees, the stomatal conductance and fixation of CO2 in plants, responding to change the δ（^13C） value of plants. In these factors, precipitation is the most evident factor to the δ（^13C） values, however, temperature is confound to reflect the δ（^13C） values of plants. Atmospheric CO2 commonly influences the intercellular and ambient CO2 pressure of leaf, resulting to various δ（^13C） values. The technique of carbon isotope used to study the water use efficiency of plants is significant in theoretics and realities, for δ（^13C） values can not only reflect water use in the course of photosynthesis, but also the relationship between carbon isotopic composition and water use efficiency that is corrective.