Abstract: The ultrastructural changes of root tip cell in midget crabapple seedling have been studied with electron microscopic method. The results showed that vacuole of treated cell with PDJ (Propyl dihydrojasmonate) was larger than
that of control, membrane bright band disappeared, electron density and permeate of plasmalemma increased after PDJ treatment in epidermic cell. Bigger nuclecus, smaller and more vacuoles, more chondriosome were appeared in second layer cells compared with control. Specialized structure was seen on the cell wall in both first and second layer cells of root tip. It approved that the changes above were beneficial to draught tolerance and water utilizition for plant.

Key words: Propyl dihydrojasmonate ( PDJ), Midget crabapple, Ultrastructure