| Field trials were carried out in Yunnan tobacco science research institute from 2004 to 2005. Physical properties, chemical components and volatile aroma components of 119 different genotypes of tobacco samples from Yunnan Province were determined. And the relationship between chemical components and physical properties, volatile aroma components were analyzed by methods of analysis of variance, cluster analysis and regression analysis. The results showed that: (1) There existed some variation for the physical characteristics, chemical components and contents of aroma components among different flue-cured tobacco genotypes. The average of leaf length, pulling force, rag filling power and leaf specific weight was 56.00cm, 2.01N, 4.34g/cm3 and 64.97g/m2, respectively. The contents of total nitrogen (1.58%) and nicotine (1.73%) were low; the contents of total sugar (29.47%) and reducing sugar (22.88%) were high; the content of soluble protein (8.00%) was located in the proper range. Among all the volatile aroma components, the contents of products of aromatic amino, products of Maillard reaction, products degraded by cembrane, products degraded by carotene and neoplytadiene were 18.78μg.g-1, 38.32μg.g-1, 22.57μg.g-1, 69.74μg.g-1 and 900.10μg.g-1.(2) The analysis of relationship between leaf length and chemical components indicated that: tobacco leaves with different length had the different content of nicotine, and the content of nicotine increased and then decreased, but total nitrogen, total sugar and reducing sugar contents increased along with increase of leaf length. Besides, total nitrogen content would be more than nicotine content, and total sugar and reducing sugar content would be beyond the proper range after leaf length was beyond 67.84cm, so the quality of tobacco would go bad. The curve regression equations between leaf length and total nitrogen, total sugar as well as reducing sugar were built, and could be respectively described by y? = 4.5211?0.1136x+0.0011x2, y? = 56.3888?1.4336x+0.0145x2 and y? = 85.5226?2.2207x+0.0216x2, while all above equations were significant at 5% level. (3) The analysis of relationship between pulling force and chemical components indicated that: nicotine content increased after pulling force was beyond 2.52N; total nitrogen had no significant increase, but total sugar and reducing sugar were gradually increased along with increase of pulling force. The curve regression equation between pulling force and nicotine content was built, and could be described by y? = 2.5135*0.8563x, while the equation was significant at 1% level.(4) The analysis of relationship between rag filling power and chemical components indicated that: the rag filling power had negative significant correlation with reducing sugar at 0.01 level, tobacco with different rag filling power had the different content of nicotine, and the content of nicotine increased and then decreased; total nitrogen had no significant change along with increase of rag filling power. The curve regression equation between rag filling power and reducing sugar content was built, and could be described by y? = 2.5135*0.8563x, while the equation was significant at 1% level.(5) The analysis of relationship between leaf specific weight and chemical components indicated that: the leaf specific weight had positive correlation with chemical components. Nicotine content increased with the leaf specific weight at 60.77 g/m2~82.17 g/m2, otherwise decreased; total nitrogen had no significant change along with increase of leaf specific weight. Total sugar and reducing sugar increased after leaf specific weight was beyond 69.78 g/m2, otherwise decreased.(6) The cluster analysis results indicated that there were the inherent relationship between total nitrogen as well as the soluble protein and volatile aroma components. The group with the lowest contents of total nitrogen (1.00%~1.47%) and the soluble protein (4.03%~7.60%) had the lowest contents of products of aromatic amino acid metabolism, and products degraded by cembrane and neoplytadiene, but the highest contents of products of Maillard reaction and products degraded by carotene. The group with the medium contents of total nitrogen (1.53%~1.88%) and the soluble protein (8.42%~10.34%) had the highest contents of products degraded by cembrane, neoplytadiene and volatile aroma components, and the medium contents of products of aromatic amino acid metabolism and products degraded by carotene, but the lowest contents of products of Maillard reaction. The group with the highest total nitrogen (1.94%~2.45%) and the soluble protein (10.39%~13.09%) had the highest content of products of aromatic amino acid metabolism, and the medium contents of products of Maillard reaction, degraded by cembrane, neoplytadiene and volatile aroma components, but the lowest content of products degraded by carotene. Besides, the canonical correlation analysis showed that there existed close relationship between contents of total nitrogen as well as the soluble protein and volatile aroma components except products of Maillard reaction.(7) The cluster analysis results indicated that there was no inherent relationship between the content of nicotine and volatile aroma components except products degraded by cembrane, and no significance was found among different groups of volatile aroma components.(8) The group with the lowest content of total sugar (17.83%~19.71%) had the highest contents of products of aromatic amino acid metabolism, products degraded by carotene, neoplytadiene, volatile aroma components, but the lowest content of products of Maillard reaction and products degraded by cembrane. The group with the medium content of total sugar (23.71%~29.91%) had the medium contents of products of aromatic amino, products degraded by cembrane, products degraded by carotene, neoplytadiene and volatile aroma components, but the highest content of products of Maillard reaction. The group with the highest content of total sugar (30.02%~36.27%) had the lowest content of products of aromatic amino acid metabolism, products degraded by carotene, neoplytadiene, volatile aroma components, and the medium content of products of Maillard reaction, but the highest content of products degraded by cembrane. So tobacco quality of this group may be worse than other groups. Besides, there were no significance in different groups of volatile aroma components.(9) The cluster analysis results indicated that: there was the positive correlation between reducing sugar and volatile aroma components. The group with the lowest content of reducing sugar (12.08%~21.38%) had the lowest contents of products of aromatic amino acid metabolism, products of degraded by cembrane, neoplytadiene, and volatile aroma components, but the medium contents of products of Maillard reaction and products degraded by carotene. The group with the medium content of reducing sugar (22.24%~26.52%) had the highest contents of products of aromatic amino acid metabolism, products of Maillard reaction, products degraded by carotene, neoplytadiene and volatile aroma components except products degraded by cembrane. The group with the highest content of reducing sugar had the medium contents of products of aromatic amino acid metabolism, neoplytadiene, volatile aroma components, and the lowest contents of products of Maillard reaction and products degraded by carotene, but the highest content of products degraded by cembrane.
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