Morphological characteristics of Ulmus pumila L. seeds during artificial aging

In this study, morphological characteristics of Ulmus pumila seeds during artificial aging was studied. The seeds were treated at a high temperature of 37℃ and high humidity (100% relative umidity). U. pumila L. seeds during artificial aging were examined using electron microscope, optical microscope and TUNEL method. The results showed that a few TUNEL positive cells were found in the root cap (RC) on the first day of artificial aging. Then TUNEL positive cells gradually appeared at shoot apex (SA), cotyledons (C) and so on during the next few days. Until the sixth day of aging time some cells were disintegrated, highly condensed cytoplasm appeared, membranes lost their protective capability and were found to be susceptible to epiphyte. We also used CaCl2 to treat Elm seeds, but TUNEL positive cells were not found.