Sicher R C
USDA-ARS, Plant Sciences Institute, Beltsville Agricultural Research Center, 10300 Baltimore Avenue, Beltsville, MD, 20705, USA,
Photosynth Res. 2001;68(3):193-201. doi: 10.1023/A:1012951708207.
Effects of atmospheric carbon dioxide enrichment on nitrogen metabolism were studied in barley primary leaves (Hordeum vulgare L. cv. Brant). Seedlings were grown in chambers under ambient (36 Pa) and elevated (100 Pa) carbon dioxide and were fertilized daily with complete nutrient solution providing 12 millimolar nitrate and 2.5 millimolar ammonium. Foliar nitrate and ammonium were 27% and 42% lower (P </= 0.01) in the elevated compared to ambient carbon dioxide treatments, respectively. Enhanced carbon dioxide affected leaf ammonium levels by inhibiting photorespiration. Diurnal variations of total nitrate were not observed in either treatment. Total and Mg(2+)inhibited nitrate reductase activities per gram fresh weight were slightly lower (P </= 0.01) in enhanced compared to ambient carbon dioxide between 8 and 15 DAS. Diurnal variations of total nitrate reductase activity in barley primary leaves were similar in either treatment except between 7 and 10 h of the photoperiod when enzyme activities were decreased (P </= 0.05) by carbon dioxide enrichment. Glutamate was similar and glutamine levels were increased by carbon dioxide enrichment between 8 and 13 DAS. However, both glutamate and glutamine were negatively impacted by elevated carbon dioxide when leaf yellowing was observed 15 and 17 DAS. The above findings showed that carbon dioxide enrichment produced only slight modifications in leaf nitrogen metabolism and that the chlorosis of barley primary leaves observed under enhanced carbon dioxide was probably not attributable to a nutritionally induced nitrogen limitation.
研究了大气二氧化碳浓度升高对大麦初生叶（Hordeum vulgare L. cv. Brant）氮代谢的影响。将幼苗种植在室内，分别处于环境二氧化碳浓度（36 Pa）和升高的二氧化碳浓度（100 Pa）条件下，每天用提供12毫摩尔硝酸盐和2.5毫摩尔铵的完全营养液施肥。与环境二氧化碳处理相比，升高二氧化碳处理下叶片中的硝酸盐和铵分别降低了27%和42%（P≤0.01）。二氧化碳浓度升高通过抑制光呼吸影响叶片铵水平。两种处理均未观察到总硝酸盐的日变化。在8至15天龄时，与环境二氧化碳相比，升高二氧化碳处理下每克鲜重的总硝酸盐还原酶活性和镁离子抑制的硝酸盐还原酶活性略低（P≤0.01）。除了在光周期的7至10小时之间，此时酶活性因二氧化碳浓度升高而降低（P≤0.05）外，两种处理下大麦初生叶中总硝酸盐还原酶活性的日变化相似。在8至13天龄时，谷氨酸含量相似，谷氨酰胺水平因二氧化碳浓度升高而增加。然而，在15和17天龄观察到叶片变黄时，谷氨酸和谷氨酰胺均受到升高二氧化碳的负面影响。上述研究结果表明，二氧化碳浓度升高仅对叶片氮代谢产生轻微影响，在二氧化碳浓度升高条件下观察到的大麦初生叶黄化现象可能并非由营养诱导的氮限制所致。
