氮素营养水平对衰老期烟叶氮代谢的影响及品种间差异

为揭示品种间烟叶品质的差异和筛选耐氮肥品种，研究了烤烟品种在不同氮素营养条件下氮代谢的差异。结果表明:氮低效与氮高效品种相比，可溶性蛋白和总氮降解量大，谷氨酰胺合成酶（GS）活性低，降幅大，谷氨酸脱氢酶（GDH）活性高，硝酸还原酶（NR）活性低，氨气补偿点高，品种间差异显著。随着施氮量的增加，氮低效品种氮素营养物质降解量百分数高，GS活性降幅大且受施氮量影响较小，GDH活性和氨气挥发潜力增大，与氮高效品种相比差异显著。NC89和豫烟10号分别在施氮量在45.00和60.00 kg?hm-2时氮代谢生理强度最大，而且豫烟10号各处理间差异小于NC89。说明不同氮效率品种烟叶的氮素再同化和转移能力存在差异，氮低效品种对氮素再同化量小，再转移量大，对氮素的应用范围广，调节能力强，而氮高效品种再同化量大，转移量小，对氮素的应用范围小，调节能力弱。烟叶衰老期氮代谢与烟叶衰老速度有关，其中GS对NH4+的再同化能力和质外体对NH4+的转移能力起主导作用。 

Effect of nitrogen nutrition on ageing tobacco leaf nitrogen metabolism and difference among varieties

The differences of nitrogen (N) metabolism under different nitrogen nutrition supply were investigated for revealed the differences of tobacco quality among varieties and selected varieties resistance to nitrogen. The results showed that, compared with N efficient variety, N inefficient variety had large amount of soluble protein and total N degradation, low glutamine synthetase (GS) and nitrate reductase (NR) activity, high glutamate dehydrogenase (GDH) activity and ammonia compensation point. With the increase of N application, N inefficient variety has the high percentage of nitrogen nutrient degradation, GS activity has big decreasing amplitude and less influenced by N application, GDH activity and ammonia volatilization potential increase. It has a significant difference between N use efficient and inefficient varieties.NC89 and Yuyan10 reached the largest N metabolism physical strength in the N application rate at 45.00 and 60.00 kg?hm-2 respectively and the differences among the treatments is Yuyan10 less than NC89. This indicates that, different N use efficiencies varieties on N assimilation and transfer ability were different. N inefficient variety has small amount of N reusing and large amount of retransfer, wide scope of application of N nutrition and have strong adjustment ability. N efficient variety has large amount of N reusing and small amount of retransfer, small scope of application of N nutrition and have weak adjustment ability. N metabolism associated with tobacco leaf aging speed, the ability of GS for NH4+ assimilation and apoplast for NH4+ transfer plays a leading role.