大气CO2浓度倍增对植物暗呼吸的影响

以长期生长于350和700μmolCO_2·mol~(-1)空气的开顶式培养室的杜仲(Eucommia ulmoides Oliv.)、紫花苜蓿(Medicago sativa L.)、玉米(Zea mays L.)等10种植物的离体成熟叶片或整株为材料,研究不同测定温度(15～35℃)下,CO_2浓度倍增对植物暗呼吸的影响。结果表明:在较低温度(15℃、20℃)下,CO_2浓度倍增对植物暗呼吸没有显著效应,在较高温度(30℃、35℃)下多数被测植物的暗呼吸显著增强。讨论了实验所得结果在未来全球气候变化中的可能的意义。

RESPONSES OF PLANT DARK RESPIRATION TO DOUBLED CO_2 CONCENTRATION

Ten species of plants were grown at ambient (350 mol CO2 mol air) and doubled (700 mol CO2 mol-1 air) CO2 concentrations at ambient temperature and illumination in order to examine changes of dark respiration of whole seedlings or detached leaves. Effects of CO2 on dark respiration were determined by brief exposure (<5min) to corresponding CO2 concentration and temperatures (15,20,25,30 and 35C) with infrared CO2 analyzer. The reductions in dark respiration on a weight base for leaves of East-Liaoning oak (Quercus liaotungensis Koidz.) at 15,20 and 25C and of soybean (Glycine max L.) at 20,25,30 and 35C and for whole seedlings of three-coloured amaranth (Amaranthus tricolor L.) at 15 and 20C and cucumber (Cucumis sativus L.) at 15C measured at elevated concentration relative to the ambient CO2 concentration were observed. No significant difference in respiration responded was observed to elevated or ambient CO2 concentrations at 15C in maize ( Zea mays L.) seedlings and alfalfa (Medicago saliva L.) leaves, at 35C in East-Liaoning oak leaves and at 20,25 and 30C in three-coloured amaranth seedlings. However CO2 efflux in leaves of weeping willow (Salix babylonica L.), simon poplar (Populus simonii Carr.) and eucommia (Eucommia ulmoides Oliv.) at 15,20,25,30 and 35C, alfalfa at 20,25,30 and 35C ,East-Liaoning oak at 30C , maize at 15C, seedlings of common buckwheat (Fagopyrum esculentwn Moench) at 15,20,25,30 and 35C , cucumber and maize at 20,25,30 and 35C and three-coloured amaranth at 35C showed an increase at elevated in contrast to ambient CO2 concentration. In general,at lower temperatures (i.e. 15,20C) there was no significant difference between elevated and ambient CO2 concentration for dark respiration, while at higher temperatures (i.e. 30,35C) elevated CO2 concentration positively stimulate dark respira- tion. It has not yet been described that double CO2 concentration could enhance plant dark respiration at 30 and 35C. Impacts of the characteristics in dark respiration on the future changes of vegetation and its mechanism were discussed.