Relationship Between Aroma Constituent, Sensory Quality And The Alkaloid Content In Different Genotypes Of Flue-cured Tobacco

Field experiments were conducted to study the genetic variation rules in the parents and F₁ combinations of flue-cured tobacco and heterosis performance of alkaloid content in Yunnan tobacco science research institute from 2007 to 2008. The correlations between aroma constituent, sensory quality and the alkaloid content were analyzed. The main conclusions were as follows:1. Descriptive statistics analysis was done for alkaloid content in the F₁ combinations and parents of flue-cured tobacco. There existed widely variation for alkaloid content between the F₁ combinations and parents, and the content of total plant alkaloid, nicotine and nornicotine in parents exceeded those in F₁ combinations. The content of total plant alkaloid for F₁ combinations was 1.87%±0.69% and 2.02%±0.77% for parents. The content of nicotine for F₁ combinations was 1.66%±0.62% and 1.82%±0.74% for parents. The content of nornicotine for F₁ combinations and parents were 0.07%±0.08% and 0.08%±0.04% respectively. The content of anatabine for F₁ combinations was 0.01 %, the same as parents. The content of anatasine was 0.10 % for both F₁ combinations and parents. The content of myosmine for F₁ combinations was 0.002%, the same as parents.2. The different significance for alkaloid content between the F₁ combinations and parents of flue-cured tobacco was tested. Comparing with the content of patents, the contents of anatasine and anatabine in F₁ combinations of flue-cured tobacco were highly significantly higher than low-parent value, and the content of various alkaloids was more than mid-parent value and low-parent value. The indexes of F₁ combinations including total plant alkaloid, nornicotine, anatabine and myosmine were lower than their high-value parent. The contents of nicotine and anatasine were higher than their high-parent value, but weren't up to significant difference level.3. Correlation analysis between parents and offspring of alkaloid content in flue-cured tobacco showed that total plant alkaloid had significantly positive correlations with mid-parent value of two parents and high-parent value. Anatasine showed significantly positive correlation with high-parent value, and it had remarkably significantly positive correlations with their mid-parent value and low-parent value. There existed highly significantly positive correlations between anatabine with high-parent value, low-parent value and their mid-parent value.4. The heterosis of F₁ combination was analyzed and the result indicated that: 1) Nornicotine showed strongly heterosis over mid-parent, with the mean of 24.18%. Among 14 combinations, 7 combinations displayed positive heterosis over mid-parent, and it took up 71.93% of the total. There was 6 crosses showing positive heterosis over high-parent, with the proportion of 42.86%. 2) Total plant alkaloid, anatabine and nicotine performed positive heterosis over mid-parent and high-parent, and there was 6 combinations over mid-parent value accounted for 42.86%. 3) Nornicotine and anatasine both showed positive heterosis over high-parent, 7.77% was nornicotine deficiency and 29.79% was anatasine. 4) Total plant alkaloid, myosmine, anatabine and nicotine mostly performed negative heterosis over high-parent.5. The correlations between common chemical compounds and the alkaloid content in the parents and F₁ combinations were analyzed. The alkaloid content in F₁ combinations correlated with common chemical compounds better than the parents. Total plant alkaloid, nicotine, anatasine and anatabine were significantly or highly significantly negative correlations with reducing sugar and total sugar. The content of protein showed highly significantly positive correlations with total plant alkaloid and nicotine. Anatabine had positive correlations with up to significant level.6. The relationships between aroma constituent and the alkaloid content in the parents and F₁ combinations were analyzed. 1) The alkaloid content was suitable in samples with relatively higher neoplytadiene. 2) By simple correlation analysis, relativity of aroma constituent and the alkaloid content in F₁ combinations strengthened the parents. Various kinds of plant alkaloid had significantly or extremely significantly positively correlation with petroleum ether extract, products of maillard reaction and alkalinity aroma component. 3) Judging from the variation of major aroma constituent in the parents and F₁ combinations at different content level of total plant alkaloid, there was inherent connection between total plant alkaloid and aroma constituent. According to alkaloid content of the parents selected, genotypes were classified into 3 groups. In the group with lowest content of total plant alkaloid, the average content of total plant alkaloid was 16.84mg/g, however the contents of products of aromatic amino acid metabolism, products degraded by carotene and organic acid were highest (24.69μg/g, 20.93μg/g and 89.98mg/g respectively). The average content of total plant alkaloid was 25.22mg/g in the group with lowest content of total plant alkaloid. The contents of petroleum ether extract, polyphenols, products of Maillard reaction, neoplytadiene and total content of volatile aroma matter were biggest in groups with medium content of total plant alkaloid, with the mean of 47.1mg/g, 46.04mg/g, 24.5μg/g, 816.25μg/g and 882.55μg/g respectively. In the group with highest content of total plant alkaloid, the average content of total plant alkaloid was 38.3 mg/g, consisting of the highest content of alkalinity aroma components (0.163μg/g). 4) The F₁ combinations were all classified into 3 groups based on alkaloid content. In the group with lowest content of total plant alkaloid, the average content of total plant alkaloid was 11.8mg/g. The average content of total plant alkaloid was 18.41mg/g in the group with medium content of total plant alkaloid, however the contents of products of polyphenols, neoplytadiene and total content of volatile aroma matter were highest (41.67mg/g, 637.78μg/g and 694.88μg/g respectively). In the group with highest content of total plant alkaloid, consisting of the average content of total plant alkaloid (38.3mg/g), the contents of petroleum ether extract, organic acid, aromatic amino acid metabolism, products degraded by carotene, products of Maillard reaction and alkalinity aroma components were biggest in the group, with the mean of 53.18mg/g, 98.51mg/g, 22.77μg/g, 21.09μg/g, 23.67μg/g and 0.19μg/g respectively.7. The relationships between sensory quality and the alkaloid content in the parents and F₁ combinations were analyzed. 1) The sensory quality of the parents showed medium aroma quality, some rich aroma volume, some moderate remaining flavor, less offensive odor, faint irritation, combustibility, grey ash color, appropriate physiological strength and medium taste concentration. The scores of aroma volume, remaining flavor, offensive odor, combustibility, ash color, point, physiological strength and taste concentration in F₁ combinations were higher than in parents. 2) The parent genotypes studied were all classified into 3 groups based on alkaloid content. The group with medium content of total plant alkaloid had the highest score of aroma quality, aroma volume, remaining flavor, offensive odor, irritation, combustibility, ash color, and point. The scores of physiological strength and taste concentration were biggest in groups with highest content of total plant alkaloid. 3) Based on alkaloid content, the F₁ combinations were all classified into 3 groups. The group with lowest content of total plant alkaloid had the trend of highest score of aroma quality, aroma volume, remaining flavor, offensive odor, irritation and point. The scores of physiological strength and taste concentration were biggest in groups with highest content of total plant alkaloid.