Wullschleger S D, Norby R J, Hendrix D L
Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6034, USA.
Tree Physiol. 1992 Jan;10(1):21-31. doi: 10.1093/treephys/10.1.21.
Seedlings of yellow-poplar (Liriodendron tulipifera L.) and white oak (Quercus alba L.) were exposed continuously to one of three CO(2) concentrations in open-top chambers under field conditions and evaluated after 24 weeks with respect to carbon exchange rates (CER), chlorophyll (Chl) content, and diurnal carbohydrate status. Increasing the CO(2) concentration from ambient to +150 or +300 microl l(-1) stimulated CER of yellow-poplar and white oak seedlings by 60 and over 35%, respectively, compared to ambient-grown seedlings. The increases in CER were not associated with a significant change in stomatal conductance and occurred despite a reduction in the amounts of Chl and accessory pigments in the leaves of plants grown in CO(2)-enriched air. Total Chl contents of yellow-poplar and white oak seedlings grown at +300 microl l(-1) were reduced by 27 and over 55%, respectively, compared with ambient-grown seedlings. Yellow-poplar and white oak seedlings grown at +300 microl l(-1) contained 72 and 67% more morning starch, respectively, than did ambient-grown plants. In contrast, yellow-poplar and white oak seedlings grown at +300 microl l(-1) contained 17 and 27% less evening sucrose, respectively, than did plants grown at ambient CO(2) concentration. Diurnal starch accumulation and the subsequent depletion of sucrose contributed to a pronounced increase in the starch/sucrose ratio of plants grown in CO(2)-enriched air. All seedlings exhibited a substantial reduction in dark respiration as CO(2) concentration increased, but the significance of this increase to the carbohydrate status and carbon economy of plants grown in CO(2)-enriched air remains unclear.
在田间条件下，将黄杨（北美鹅掌楸）和白栎的幼苗置于开顶式生长箱中，持续暴露于三种二氧化碳浓度之一的环境中，并在24周后对其碳交换率（CER）、叶绿素（Chl）含量和昼夜碳水化合物状况进行评估。与在环境二氧化碳浓度下生长的幼苗相比，将二氧化碳浓度从环境水平提高到+150或+300微升升-1，分别使黄杨和白栎幼苗的CER提高了60%和超过35%。CER的增加与气孔导度的显著变化无关，尽管在高二氧化碳浓度空气中生长的植物叶片中Chl和辅助色素的含量有所减少，但CER仍出现了增加。与在环境二氧化碳浓度下生长的幼苗相比，在+300微升升-1浓度下生长的黄杨和白栎幼苗的总Chl含量分别降低了27%和超过55%。在+300微升升-1浓度下生长的黄杨和白栎幼苗，其早晨的淀粉含量分别比在环境二氧化碳浓度下生长的植物多72%和67%。相比之下，在+300微升升-1浓度下生长的黄杨和白栎幼苗，其傍晚的蔗糖含量分别比在环境二氧化碳浓度下生长的植物少17%和27%。昼夜淀粉积累以及随后蔗糖的消耗导致了在高二氧化碳浓度空气中生长的植物的淀粉/蔗糖比值显著增加。随着二氧化碳浓度的增加，所有幼苗的暗呼吸都大幅降低，但这种增加对在高二氧化碳浓度空气中生长的植物的碳水化合物状况和碳经济的意义仍不清楚。
