ULTRASTRUCTURAL-CHANGES IN THE APICAL MERISTEM OF LIATRIS-SPICATA CV CALLILEPIS DURING DORMANCY BREAKING

Electron-microscopic studies of the apical meristem in corms of liatri s (Liatris spicata (L.) Willd.) aimed to ascertain whether any structu ral changes were initiated during the breaking of dormancy. The ultras tructure of the cells examined in dormant corms shows many vacuoles wi th abundant dispersed electron-dense material. Different types of plas tids are observed: eoplasts, amyloplasts and etioplasts. These organel les proliferate at the beginning of dormancy release (after five weeks at a low temperatures) and the vacuolar contents tend to unite to for m large lipid-protein bodies. Soon after the breaking of dormancy (aft er nine weeks of low temperatures) the plastids cease to proliferate a nd they appear homogeneous. These results suggest that the sequence of reactions involved in dormancy breaking may be closely related to pla stid proliferation.