Preliminary Report on the Scanning Electron Microscope Observation of Epidermal Micromorphology during Tobacco Flue-curing

Purpose To study the structural changes of flue-cured tobacco’s epidermis micromo-rphological characteristics during curing.

Method The suitable ripe leaf of flue-cured tobacco ‘K326’ was used as material, the micromorphological characteristics of the lower epidermis of tobacco leaves during different curing processes (before curing, the end of 36 ℃, the end of 38 ℃, the end of 42 ℃, the end of 48 ℃, the end of 54 ℃ and the end of 68 ℃) were observed and compared by scanning electron microscope (SEM).

Result With the increase of curing temperature, the length of stomata decreased from 27.46 μm before curing to 22.47 μm at the end of 68 ℃, the density of stomata increased from 103.76 pieces/mm² before curing to 167.48 pieces/mm² at the end of 68 ℃, and gradually protruded above the epidermis, the shapes varies from broad ellipse to ellipse. The inner margin of outer stomata ledge varies from shallow wave to deep wave; the density of epidermal cells increased from 463.24 pieces/mm² before curing to 895.42 pieces/mm² at the end of 68 ℃, the patterns of anticlinal wall deepens significantly, and the periphery wall gradually protrudes. The cuticle of epidermal cells ranges from nearly smooth to striped or even ridged. The waxy ornamentation of epidermis varies from sparse small granule to large granule or even lump. The shape of the top cells of glandular hair with secretory function changed from full to sunken, and some of them fell off from the stalk cells.

Conclusion The characteristics of epidermis micropattern changed significantly during flue-cured tobacco curing, and the microstructure features can be used as reference for the curing of flue-cured tobacco.