Histology and Cytology Research on Development of Tobacco Leaf

The change of tissue and cell structure of flue-cured tobacco lower leaf was examined continuously from emergence to over maturity with paraffin method and electron microscopy chemistry.The results showed that:along with the development of leaves, the thickness of upper or lower epidermis changed little;the thickness of palisade tissue increased initially and then decreased, while it increased slightly through over maturity;the thickness of spongy tissue continuously increased;the thickness ratio of palisade tissue to leaf reached its peak 36 days after leaf emergence, and the thickness ratio of palisade tissue to spongy tissue changed unsignificantly;the organelles, such as starch grain, osmiophilic globule and chloroplast, formed, intumesced, then decomposed at over maturity stage;the number of high electron densification granulars decreased, and then increased at over maturity stage.