| Aromatic matter was the important factor of tobacco quality. Quality, volume and flavor of aroma were determined by ingredient, content, proportion and interaction of aromatic components. The phenotype of aromatic matter was controlled by genetic and environment factors. The former affected the property and kind of aromatic matters; the latter mainly affected the content and proportion of aromatic matters. Currently, deficiency of volume of aroma was one of limiting factors, which affected increase of tobacco quality. Therefore, it was very important to separate, identify and classify for the aromatic components, and to regulate quality of aroma by agronomic measures. The experiments were conducted at Xinyang and Sanmenxia in 2003. Effects of different nitrogen level, nitrogen form, ratio of fertilizer to organic manure and different upper leaf harvesting methods on content of aromatic matters of flue-cured tobacco were systematically studied through four single-factor experiments. The results were as follows:1. The experiment of different nitrogen levels showed that: (1) Under the different nitrogen levels in Xinyang, the variation was significant at 0.05 level for products of Maillard reaction and highly significant at 0.01 level for products degraded by cembrane among different leaf positions. However, the variation was not significant at 0.05 level for neoplytadiene, products degraded by carotenoid, products of aromatic amino acid metabolism and total content of volatile aroma components among different positions. For different treatments of nitrogen level, the variation of neoplytadiene and total content of volatile aroma components was significant at 0.05 level; the variation of products of Maillard reaction, products of aromatic amino acid metabolism, products degraded by carotenoid and products degraded by cembrane was significant at 0.01 level. (2) For different treatments of nitrogen level, the treatment of 75 kg/hm~2 could increase effectively the content of neoplytadiene, products degraded by carotenoid, products of aromatic amino acid metabolism, products of Maillard reaction, products degraded by cembrane and total content of volatile aroma components of cured leaves among different positions.2. The experiment of different nitrogen forms showed that: (1) There existed highly significant difference for content of neoplytadiene, products of aromatic amino acidmetabolism, products of Maillard reaction, products degraded by cembrane and total content of volatile aroma components among different positions. The variation of main volatile aroma components was significant at 0.01 level except the products degraded by carotenoid among the different treatments. (2) As to treatments of different nitrogen forms, all kinds of content of aromatic matters and total content of volatile aroma components showed an increasing trend with increasing of nitrate nitrogen proportion among different positions, and the treatment of 70%nitrate nitrogen + 30% ammonia nitrogen was the best. (3) Under the condition of treatment of 75 kg/hm2, the correlation between different nitrate nitrogen proportion and content of volatile aroma matters was positive with different degrees. For lower leaves, it was significant at 0.01 level for the correlation between different nitrate nitrogen proportion and content of products of Maillard reaction. For cutters, correlation coefficients of different nitrate nitrogen proportion were significant at 0.01 level with content of neoplytadiene, and total content of volatile aroma components, and significant at 0.05 level with content of products of Maillard reaction, and products degraded by cembrane, respectively. For upper leaves, correlation coefficients between different nitrate nitrogen proportion and content of products of Maillard reaction, and products degraded by cembrane were significant at 0.01 level; correlation coefficients between the different nitrate nitrogen proportion and content of products of aromatic amino acid metabolism were also significant at 0.05 level. Therefore, under the condition of treatment of 75 kg /hm2, the total content of volatile aroma components could be increased by adding nitrate nitrogen fertilizer to some extent.3. The experiment of different ratio of fertilizer to organic manure showed that: (1) Under the condition of applying different ratio on organic and inorganic fertilizer, the variation was significant at 0.01 level for content of neoplytadiene, products of aromatic amino acid metabolism and total content of volatile aroma components, and was not significant at 0.05 level for products degraded by carotenoid, products of Maillard reaction and products degraded by cembrane among different positions.The variation of the total content of volatile aroma components among different treatments was significant at 0.01 level. (2) Compared with treatment of no nitrogen fertilizer (To), the content of neoplytadiene of cured leaves of different positions showed an increasing trend in general with increasing of organic nitrogen proportion; the content of neoplytadiene of treatment of 50% chemical fertilizer + 50% cake fertilizer was the highest, and the content of neoplytadiene began to decrease when nitrogen proportion of cake fertilizer exceeded 50%. The proportion of content of neoplytadiene to total content of volatile aroma matter did notshow large difference among different positions. The treatment of 50% chemical fertilizer + 50% cake fertilizer could increase effectively the total content of volatile aroma components of cured leaves of different positions. Compared with the treatment of To, content of volatile aromatic matter of lower leaves, cutters and upper leaves had increased 76.58%, 45.59% and 42.32% for the treatment of 50% chemical fertilizer + 50% cake fertilizer. (3) Products degraded by carotenoid of cured leaves of different positions showed an increasing trend with increasing of organic nitrogen proportion under the certain range. The content of products degraded by carotenoid began to decrease when nitrogen proportion of cake fertilizer exceeded 50%. From content of products degraded by carotenoid of different treatments, the treatment of 50% chemical fertilizer + 50% cake fertilizer was the best in Xinyang tobacco-planting area. Compared with the treatment of To, content of products degraded by carotenoid of lower leaves, cutters and upper leaves had increased 78.04%, 73.02% and 58.10% for the treatment of 50% chemical fertilizer + 50% cake fertilizer. (4) The content of products of aromatic amino acid metabolism, products of Maillard reaction and products degraded by cembrane showed the same trend as the content of neoplytadiene and products degraded by carotenoid, and had an increasing trend with increasing of organic nitrogen proportion. The treatment of 50% chemical fertilizer + 50% cake fertilizer was still the best, and the content of aromatic matters began to decrease when nitrogen proportion of cake fertilizer exceeded 50%. Compared with the treatment of To, the avgrage content of products of aromatic amino acid metabolism, products of Maillard reaction and products degraded by cembrane of cured leaves among different positions had increased 50.76%, 58.89% and 54.08%, respectively.4. The experiment of different harvesting methods of upper leaves showed that: (1) Compared with the common used harvesting method, the method of picking 4~6 upper leaves with stem together could increase total sugar content, reducing sugar content and K content, and decrease starch content, and keep the almost same content of nicotine, total nitrogen and protein in flue-cured leaf. (2) Flue curing upper leaves with stem together increased total content of volatile aromatic matter significantly. The important aromatic matter content of neoplytadiene, products degraded by caretene, products of aromatic amino acid metabolism, products of Maillard reaction and products degraded by cembrane were increased in various degrees. However, the proportion of content of each group aroma matter to total content of volatile aroma matter did not show large difference between the method of picking 4~6 upper leaves with stem together and the method of common used picking. Therefore, it was an effective way to coordinate the chemical composition of cured...
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