ECOPHYSIOLOGY OF SEED-GERMINATION IN ENDEMIC LABIATES OF CRETE

Ecophysiological aspects of seed germination were investigated in four aromatic labiate plants of Crete Origanum dictamnus (dittany), Sideri tis syriaca L. ssp. syriaca (Cretan mountain tea), Salvia pomifera L. ssp. pomifera (gall-bearing sage), and Salvia fruticosa (three-lobed s age). Experiments were performed both at constant temperatures and dar kness as well as under temperature and light conditions simulating tho se prevailing in nature during the main germination periods (i.e., sta rt and middle of the rainy season, November and February-March, respec tively). In three out of the four species, no particular dormancy was revealed and germination occurred rather promptly, although in a rathe r narrow range of cool temperatures and at a relatively slow rate; bot h characteristics determine and/or support an early, autumn seed germi nation and seedling establishment. In the fourth plant, Sideritis syri aca, germination was manifested at relatively warm temperatures and at a considerably faster rate, in accordance with its alpine distributio n favoring spring seedling emergence and establishment. All four speci es tested showed an intermediate response towards light, as a result o f their intermediate levels of active phytochrome maintained in darkne ss. Therefore seed germination was partially manifested in darkness bu t it was significantly enhanced (particularly at suboptimal temperatur es) by white or red light; on the other hand, illumination with far-re d light (simulating light conditions under a canopy) resulted in signi ficant inhibition compared to dark controls.