Abstract: In order to study the cell development and maturation patterns of flue-cured tobacco, the changes in cell ultrastructure of variety NC 89 during development and maturation process were studied by electron microscope with the samples obtained in Tangjie Township, Jiaxian County, Pingdingshan City in 2008. The results showed that cell division and increment played a major role from 1 to 11 days of leaf age. From the 21st day of leaf age, the cell division stopped, and the cell volume began to increase rapidly. Cells entered exuberant functional period on the 31st day of leaf age and begun to accumulate assimilation products on the 41st day. The period from 21st day to the 41st day of leaf age was essential to the quality of tobacco leaf. During crudity stage, the cells of immature leaves could accumulate a few of assimilation products. Along with the increasing of maturity, the chloroplast and cell nuclear gradually degraded. In overmature stage, the starch granules begun to degrade．

Key words: flue-cured tobacco, development, maturation, ultrastructure