增强UV-B辐射和SO2作用下植物光合响应及其相对抗性

 研究了20种野外生长的树种在增强UV-B、NaHSO3的作用下，它们的光合作用响应及其对这两种胁迫的抗性。研究结果表明，这些植物的抗性可分为抗性强、抗性中等和敏感3种类型。UV-B、NaHSO3以及UV-B+NaHSO3 3种处理与这些植物光合作用受抑制程度呈现良好的线性关系，说明这些植物在防御UV-B和NaHSO3伤害的能力方面有一致性，没有种的特异性。结果还表明，在这些植物中NaHSO3增强了UV-B对它们的抑制作用，敏感类型植物尤为明显。 

PHOTOSYNTHETIC RESPONSES OF PLANTS TO SUPPLEMENTARY UV-B RADIATION AND SULFITE AND THEIR RESISTANCES

The increase in UV-B radiation and airborne SO2 has become a serious environmental issue. In this paper the photosynthetic responses of 20 species of common tropical and subtropical greening trees to supplementary UV-B radiation and/or SO2 (simulated by sulfite solution) were studied. Trees were grown under natural conditions in the South China Botanic Garden. The relative resistances of these trees were estimated through the photosynthesis and chlorophyll fluorescence characteristics. Leaves were collected from the canopy of the 20 species and treated with UV-B radiation, NaHCO3 and UV-B+NaHCO3 for 72 h in the laboratory. Photosynthetic O2 evolution rate of these isolated leaves was then measured by leaf disc oxygen electrode system (Hansatech, King’s Lynn, UK), and their fluorescence emission (Fv/Fm) was tested using a PAM-Fluorometer (Walz, Effeltrich, Germany). Results showed that these plants can be classified into three types: high resistance, medium resistance and sensitive according to their resistant abilities to supplementary UV-B and/or SO2. They further showed that the UV-B radiation damage to the trees could be enhanced by treatment with SO2. The inhibition induced from a single stress factor, SO2 or UV-B, had a positive relationship with that from combined factors, UV-B+NaHCO3, in these tested trees. The response of chlorophyll fluorescence characteristics of these trees to environmental stress and applications of this technique for studying forest ecology, environmental physiology and stress physiology were also discussed.