Abstract: In order to investigate the appropriate nitrogen application amount for fragrant-flavor tobacco in Nanyang tobacco-growing areas, this paper studied the expression characteristics of glutamine synthase (GS) isozyme protein and the changes of related physiological indexes at mature stages of different cultivars using split zone test design and treated by 3 nitrogen application treatments. The results showed that the activities of GS1, GS2 and NR at maturity stage of NC71 were lower, GDH activity was higher, nitrogen assimilation and reutilization ability were also lower. At the same time, the content of NH+4 in apoplast and ammonia volatilization were both high, thus having high nitrogen efficiency in mature stage, and 52.5~60.0 kg/hm2 pure nitrogen application was reasonable. Yunyan 99 had higher GS1 activity at mature stage, nitrogen degraded by aging was reused in a large quantities, and the ammonia volatilization was also low, therefore, the total nitrogen content in leaves was higher, aging could be easily delayed. It was ideal to apply 25~30 kg/hm2 of pure nitrogen. The nitrogen efficiency of “Qushou 1” was between the other 2 varieties. It was suit to apply 40~45 kg/hm2 of pure nitrogen. Correlation analysis showed that there was a significant or extremely significant correlation between GS isoenzyme activity and leaf nitrogen metabolic index, which could be used as an important basis for studying nitrogen metabolism characteristics of flue-cured tobacco.

Key words: flue-cured tobacco, glutamine synthase(GS) isozyme, nitrogen metabolism, Nanyang tobacco-growing area

摘要： 为探明南阳烟区浓香型烤烟品种的适宜施氮量，采用裂区试验设计，通过3个施氮量处理，研究了不同烤烟品种（NC71、云烟99、渠首一号）成熟期谷氨酰胺合成酶（GS）同工酶蛋白表达特性及相关生理指标的变化动态。结果表明：NC71成熟期GS1、GS2和硝酸还原酶（NR）活性较低，谷氨酸脱氢酶（GDH）活性较高，具有较低的氮素同化和再利用能力，同时质外体NH+4浓度和氨气挥发量均较高，因此具有较高的成熟期氮效率，施氮量以纯氮52.5~60.0 kg/hm2为宜。云烟99成熟期具有较高的GS1活性，衰老降解的氮素被大量再利用，氨气挥发量也较低，因此叶片总氮含量较高，容易贪青晚熟，施氮量以25~30 kg/hm2最为理想。渠首一号氮效率居于两者之间，适合纯氮40~45 kg/hm2的中等肥力条件。相关性分析表明，GS同工酶活性与叶片氮代谢生理指标有显著或极显著相关性，可以作为研究烤烟品种氮代谢特征的重要依据。

关键词: 烤烟, 谷氨酰胺合成酶同工酶, 氮代谢, 南阳烟区