Abstract: Ultrastructural changes of pericarp of cucumber in vivowere investigated in cucumber cultivars
D0313 and 649 during senescence. The results showed that in the cultivar 649, cellwall dissolution was initi2
ated along the middle lamella and granum lamellae were extended towards both sides at 30 d after pollination.
At 40 d after pollination, cellwall disrup tion was advanced, grana began to dissolve and cristae ofmitochondria were fewer in number. In the cultivarD0313, dissolution of the middle lamella has occurred, grana were
dilated and single thylakoidswere distributed at 20 d after pollination. At 30 d after pollination, middle lamella disappeared, chlorop lasts degraded and cristae ofmitochondria were illegibility. So, cellwall, chlorop lasts
and mitochondria of D0313 began to degrade p rior to that of 649 during senescence. And mitochondria were
stable cellular organelles; the changes ofmitochondria were later than chlorop lasts during senescence.

Key words: Cucumber, in vivo, Senescence, Pericarp, Ultrastructure