Changes of cell ultrastructure and some physiological indexes and physical properties of tobacco leaves during bulk flue-curing | 密集烘烤过程中烟叶生理指标和物理特性及细胞超微结构变化

Chinese. 【目的】探讨密集烘烤过程中烟叶某些生理指标和物理特性及细胞超微结构变化,为烘烤工艺的优化和完善提供理论依据。【方法】采用河南农业大学设计的电热式温湿自控密集烤烟箱,研究烟叶烘烤过程中关键温度点(鲜样、38℃、42℃、48℃、54℃、干样)细胞超微结构、生理指标及物理特性的变化规律。【结果】烟叶淀粉、叶绿素和类胡萝卜素含量的变化主要在变黄前期;烟叶水分含量、厚度、密度的变化主要在变黄期和定色期;果胶和纤维素含量的变化主要在定色期,烘烤过程中叶质重的变化相对较小。细胞超微结构观察表明,细胞壁、叶绿体和细胞核在烘烤过程中的变化明显,但线粒体不易观察到;38℃染色质减少,核膜部分消失;42℃细胞出现质壁分离现象,叶绿体等细胞器游离到细胞中央,叶绿体外膜、核膜破裂,嗜锇颗粒多数呈现半空状态,基粒片层和大部分淀粉粒消失;48℃细胞壁扭曲变形,细胞核固缩;54℃后叶绿体个体形状已不易区分,所存物质基本是电子密度较弱的嗜锇物质。【结论】烘烤过程中烟叶细胞超微结构变化与烟叶物理特性、生理生化反应、内含物降解转化的程度密切相关。

English. 【Objective】 In order to provide a theoretical basis for optimization and perfection of curing technology, changes of cell ultrastructure and some physiological indexes and physical properties of tobacco leaves were studied during bulk-curing.【Method】 Changes of cell ultrastructure, some physiological indexes and physical properties were studied at key temperature points (fresh, 38℃, 42℃, 48℃, 54℃, dry sample) during flue-curing using the electric-heated flue-curing barn designed and made by Henan Agricultural University. 【Result】 The contents of the starch, chlorophyll and carotenoids of tobacco leaves changed greatly in the early yellowing stage. The differences of moisture content, thickness, density of tobacco leaves in the yellowing and leaf-drying stages were highly significant. The contents of the pectin and cellulose changed mainly in the leaf-drying stage, but leaf specific weight had a relatively small change during flue-curing. Cell ultrastructure observation indicated that cell wall, chloroplast and nucleus changed obviously, but mitochondrias were not easy to be found during flue-curing. The cell structure of the fresh leaves was normal, but chromatin decreased and part of the nuclear membrane disappeared at 38℃. Cells showed plasmolysis, chloroplast and other cellular organs freed to the central cell, chloroplast outer membrane and nuclear membrane fractured, most osmiophilic granules presented half-hollow state, grana lamella and most starch grains disappeared at 42℃. The obvious twist distortion of cell wall and nucleus pyknosis appeared at 48℃; Individual shapes of chloroplast were not apt to differentiate and the remains were basically osmiophilic materials of the weak electronic density after 54℃.【Conclusion】The changes of the cell ultrastructure of tobacco leaves were closely related to physical properties and physiological and biochemical reactions and extent of degradation and transformation of inclusion during flue-curing.