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作 者 ：段旺军，杨铁钊，刘化冰，张小全，戴 亚，李东亮

期 刊 ：植物营养与肥料学报 2011年 17卷 2期 页码：419-424

Keywords:NH3compensationpoint, Nmetabolization, glutaminesynt,

摘 要 ：为了研究不同成熟特性的烤烟品种叶片氨气补偿点及其差异，利用质外体提取方法对3个烤烟品种NC89、K326和中烟90的叶片质外体铵浓度和pH值进行了测定，并计算不同品种叶片的氨气补偿点(25℃)；同时探讨了氨气补偿点与氮素代谢的关系。结果表明，叶片氨气补偿点随着成熟衰老而上升；烟草叶片成熟衰老期氨气补偿点与谷氨酰胺合成酶活性关系密切。衰老速度快、叶片氮素状况（总氮和可溶性蛋白）低的品种谷氨酰胺合成酶活性下降幅度大，氨气补偿点升幅大，绝对值也高。因此，衰老速度快、叶片氮素状况低的品种在叶片衰老期具有更大的氨挥发潜力。品种间氨气补偿点的差异与它们的氮素代谢特性有关。

Abstract:To investigate NH₃ compensation point (χ_s) and its differences in leaves of three flue-cured tobacco genotypes and the related N metabolization, foliar apoplastic NH₄⁺ concentration and pH were measured by apoplast extraction technique, the χ_s (25℃) was calculated on the basis of measurements, and the activities of related enzymes and nitrogen parameters were also assayed. In the leaves of the three cultivars, an increase in χ_s was observed as the onset of senescence. Compared with the leaves of slow-senescing cultivar, the leaves of the rapid-senescing tobacco cultivar with lower N status had a stronger decrease in glutamine synthetase activity (GS, EC 6.3.1.2) and a more substantial increase in χ_s. These results indicate that the rapid-senescing cultivar may have a high potential for NH₃ emission from senescing leaves into the atmosphere, and the difference in χ_s values is related with the N metabolism of the cultivars.

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