硝态铵态氮比例对不同氮效率烟草苗期氮素吸收及利用的影响

【目的】为明确最有利于烤烟和白肋烟氮素利用的氮素形态配比。【方法】采用盆栽的方法，以烤烟品种中烟100和白肋烟品种TN90为材料，设置5个硝态铵态氮比例(T1:NO₃^-:NH₄⁺=100:0;T2:NO₃^-:NH₄⁺=75:25;T3:NO₃^-:NH₄⁺=50:50;T4:NO₃^-:NH₄⁺=25:75;T5:NO₃^-:NH₄⁺=0:100)，测定各处理的生物量、色素含量、硝酸还原酶(nitrate reductase,NR)和谷氨酰胺合成酶(glutamine synthetase,GS)活性、NH₄⁺-N含...

Effects of nitrate-ammonium nitrogen ratio on nitrogen absorption and utilization of tobacco seedlings with different nitrogen use efficiency

  Objectives  This study aims to identify the most effective nitrogen form and ratio for flue-cured tobacco and burley tobacco.  Methods  Pot experiment was carried out with flue-cured tobacco variety Zhongyan 100 and burley tobacco variety TN90 as materials. Five nitrate-ammonium nitrogen ratios (T1: NO₃?: NH₄+=100:0; T2: NO₃?: NH₄+=75:25; T3: NO₃?: NH₄+=50:50; T4: NO₃?: NH₄+=25:75; T5: NO₃?: NH₄+=0:100) were set up. The biomass, pigment content, the activity of nitrate reductase and glutamine synthetase, NH₄+-N content, nitrate content, total nitrogen content, total sugar content and soluble sugar content of each treatment were determined. The effects of different nitrate and ammonium nitrogen ratios on the growth, nitrogen accumulation and nitrogen metabolism of flue-cured tobacco and burley tobacco with different nitrogen use efficiency were comparatively analyzed.  Results  (1) The NR and GS activities of Zhongyan 100 were the highest when the nitrate-ammonium nitrogen ratio was 75:25. The NR activity of TN90 was the highest when the nitrate-ammonium nitrogen ratio was 50:50, and GS activity was the highest when the nitrate-ammonium nitrogen ratio was 25:75. The total sugar contents of Zhongyan 100 and TN90 were the highest (8.22% and 5.36%, respectively)when the nitrate-ammonium nitrogen ratio was 50:50. (2) The nitrate contents in leaves of TN90 and Zhongyan 100 were the lowest (343.73mg·g-1and 116.77mg·g-1, respectively) when the nitrate-ammonium nitrogen ratio was 50:50. (3) Ten indexes including shoot dry weight, total pigment content, nitrate reductase activity, glutamine synthetase activity, leaf total nitrogen content, leaf nitrogen accumulation, total sugar content, soluble sugar content, reciprocal nitrate content, leaf NH₄+-N content were comprehensively evaluated based on the principal component analysis. The flue-cured tobacco had the highest score when nitrate-ammonium nitrogen ratio was 75:25, and burley tobacco had the highest score when nitrate-ammonium nitrogen ratio was 50:50.  Conclusion  High nitrate-ammonium nitrogen ratio effectively promoted the growth and development of flue-cured tobacco, and appropriately increasing the ammonium nitrogen proportion was conducive to the formation of carbohydrates in burley tobacco leaves, thus improving the nitrogen metabolism ability of tobacco leaves. Based on the biomass accumulation and principal component analysis, the flue-cured tobacco and burley tobacco showed the best comprehensive performance when the nitrate-ammonium nitrogen ratio were 75: 25 and 50: 50, respectively.