DORMANCY LEVEL AND DORMANCY-BREAKING PRETREATMENTS IN SEEDS OF FRAXINUS ORNUS SUBSP CILICICA

Fraxinus ornus subsp. cilicica is an ornamental tree endemic to southern Turkey. The present study was carried out to determine the level of dormancy and appropriate dormancy-breaking pretreatments and to investigate interpopulational variation in seed dormancy. The seeds were collected from seven populations (Menzelet, Boztoprak, Duzici, Kozan, Pozanti, Gundogmus, Egirdir). Average percentage of sound, insect-infected, and empty seeds was 74.0, 16.8, and 9.2, respectively. Germination percentages of populations varied significantly due mainly to different percentages of sound seed. The study suggests that seeds of this taxon have deep physiological dormancy, as they required about 18 weeks of prechilling treatment at 4 degrees C for full dormancy removal, and depth of dormancy for seeds of all populations was relatively similar. Warm incubation at 20 degrees C before the prechilling was not effective in decreasing the prechilling requirement for dormancy break.