| In this study,different parts of flue-cured tobacco were taken as the research object,and the ultrastructure of leaf cells was observed.Based on digital image quantification technology,the ultrastructure indexes of leaf cells were quantified by Adobe Photoshop CC 2015 software,and the differences of ultrastructure of leaf cells between different parts were compared and analyzed.The appearance quality,physical characteristics,conventional chemical composition and neutral aroma-causing substances were determined.Pearson correlation analysis and canonical correlation analysis(CCA)were used to explore the relationship between cell ultrastructure and tobacco quality.The main results are as follows:1.Ultrastructural analysis of flue-cured tobacco leaf cells in different parts.The cell outline of flue-cured tobacco leaves was clear,and the shape was oval.The shape of cells in the upper leaves is basically round and arranged tightly and neatly;the shape of cells in the middle leaves is slightly elliptic compared with that in the upper leaves,and the arrangement is slightly loose compared with that in the upper leaves;the shape of cells in the lower leaves is basically similar to that in the upper and middle leaves,with a few cells having flat and long shapes,and the arrangement of cells is not as neat and close as that in the upper and middle leaves.The cell size of the middle leaf is close to that of the lower leaf and slightly larger than that of the upper leaf.In the cell walls of three leaf positions,there were obvious adherent distribution of cell nuclei,chloroplasts and mitochondria,and the central vacuoles were located in the middle of cells.The content of intracellular substances increased with the increase of leaf position.With the increase of flue-cured tobacco leaf position,the chloroplast outer membrane and thylakoid lamella of mesophyll cells were degraded.The appearance of chloroplast was blurred,the structure of thylakoid was loose,and a few mitochondria were distributed around the chloroplast of mesophyll cells.There were clear starch grains and osmiophilic grains in the chloroplast of mesophyll cells.The higher the position of Flue-cured tobacco leaves,the closer the organs of mesophyll cells were to the aging state,Grain content increased with leaf position.The cells of upper and lower leaves were larger than those of middle leaves;there was no significant difference among the three parts of cell shape factor;the vacuole area of lower leaves was significantly larger than that of middle leaves,the vacuole area of lower leaves was significantly larger than that of upper leaves,and the vacuole area of upper leaves was significantly larger than that of middle leaves;the vacuole area of lower leaves was significantly larger than that of upper and middle leaves.2.Appearance quality of flue-cured tobacco and its correlation with cell index.The color score ranged from 4.42 to 9.03,the maturity score ranged from 5.16 to 9.47,the leaf structure score ranged from 4.09 to 9.08,the identity score ranged from 4.74 to 8.28,the oil score ranged from 4.13 to 8.77,and the chroma score ranged from 4.31 to 9.1.There was no significant variation among the same parts,but there were significant differences among different parts.The appearance quality indexes such as color,maturity,leaf structure,identity and oil content of the middle leaves were obvious.The color score of upper leaves was higher than that of lower leaves.The color,maturity,leaf structure,identity and oil score of middle leaves were higher.The color,maturity,leaf structure and oil score of upper leaves were lower,while that of lower leaves were lower.The results of correlation analysis showed that there was a negative correlation between cell wall thickness and tobacco leaf identity score,and a positive correlation between the ratio of vacuole area to cell area and color,leaf structure and oil score.3.Physical characteristics of flue-cured tobacco and their correlation with cell indexes.The thickness of flue-cured tobacco leaves ranged from 88 to 173 microns,the pulling force ranged from 1.78 to 4.58N,slightly higher than the general value of high-quality tobacco leaves,the filling value ranged from 2.85 to 5.09 cm3/g,the equilibrium moisture content ranged from 11.02 to 14.5%,and the leaf weight ranged from 50 to 95.4 g/m2.The thickness and pulling force of upper leaves of flue-cured tobacco were bigger,the balance water content and weight of middle leaves were bigger,the filling value of lower leaves was bigger,the filling value of middle leaves was smaller,and the thickness,pulling force,balance water content and weight of lower leaves were smaller.The results of correlation analysis showed that there was a negative correlation between cell wall thickness and leaf thickness.4.Routine chemical constituents of flue-cured tobacco and their correlation with cell indexes.Protein content ranged from 6.08%to 12.85%,potassium content ranged from 0.59%to 2.64%.Compared with the standard of high-quality tobacco leaves,chlorine content ranged from 0.68%to 2.45%,content was higher,reducing sugar content ranged from 16.71%to 32.15%,content was higher,total sugar content ranged from 22.62%to 33.34%,content was higher,nicotine content ranged from 1.8%to 3.77%,total nitrogen content ranged from 1.05%to 2.73%.Extreme values were generally distributed in the upper and lower leaves,and the conventional chemical components in the middle leaves were more coordinated.The contents of nicotine and total nitrogen in upper leaves were higher,reducing sugar and total sugar in middle leaves were higher,protein,potassium and chlorine in lower leaves were higher,potassium content in upper leaves was lower,protein,chlorine and total nitrogen content in middle leaves was lower,and reducing sugar,total sugar and nicotine content in lower leaves was lowest.The results of correlation analysis showed that cell wall thickness was positively correlated with protein and chlorine,negatively correlated with reducing sugar and total sugar,and positively correlated with nicotine and total nitrogen.5.Neutral aromatic substances in flue-cured tobacco and their correlation with cell indexes.In this study,29 kinds of neutral aromatic substances were determined.The total amount of neutral aromatic substances in upper leaves ranged from 358.93 to 459.05 ug/g,in middle leaves from 535.27 to 716.62 ug/g,and in lower leaves from 298.07 to 567.8 ug/g.The total amount of carotenoid degradation products ranged from 27.83 to 57.44 ug/g,Maillard reaction degradation products ranged from 6.97 to 15.99 ug/g,aromatic amino acid degradation products ranged from 5.12 to 15 ug/g,ceberane degradation products ranged from 42.07 to 101.48 ug/g,other neutral aroma products ranged from 1.15 to 4.14 ug/g,and new phytadiene content ranged from 190.45 to 567.8 ug/g.There was no significant difference between the same part and different parts.On the whole,the content of neutral aromatic substances in the middle part was the highest,except for the lower part.The results of correlation analysis showed that with the increase of cell wall thickness,the total contents of other neutral aromatic substances,other neutral aromatic substances,cypress,and neutral aromatic substances in the middle leaves were the highest in the three parts.The total contents of carotenoid degradation products,aromatic amino acid degradation products and cetylane degradation products increased.With the increase of cell area and vacuole area of Flue-cured tobacco,the total amount of Maillard reaction degradation products and new phytadiene decreased. |
PDF Full Text Request