摘要: In order to investigate the effect of nitrogen forms on soil nitrification and plant nitrogen utilization, a pot experiment was carried out under five different rates of nitrogen forms with two flue-cured tobacco cultivars. The rhizosphere and non-rhizosphere soil nitrification, plant nitrogen utilization and key enzyme activities were evaluated. The results showed that the nitrogen forms had an important effect on growth and nitrogen uptake and accumulation of the flue-cured tobacco. Single application of nitrate nitrogen or ammonium nitrogen was not optimal to the growth and nitrogen accumulation of tobacco plant. The combined use of nitrate nitrogen and ammonium nitrogen significantly promoted the nitrification strength both of rhizosphere and non-rhizosphere soil, improved the nitrogen metabolism of the tobacco plant, and thereby increased the nitrogen accumulation. There were clear differences between the tobacco cultivars in nitrogen use efficiency in response to the nitrogen forms. The soil nitrification activities of cv. Honghuadajinyuan (HD) was the highest when the proportion of ammonium nitrogen and nitrate nitrogen was in 50:50, while for cv. Zhongyan100 (ZY100) this became 75:25. Higher rhizosphere soil nitrification activities and glutamine synthetase (GS) activity were important reasons for the high nitrogen utilization efficiency of HD.