Seed cryopreservation of Halimium and Helianthemum species

Seed germination of four Halimium species [H. atriplicifolium, H.hHalimifolium, H. ocymoides, H. umbellatum] and eight Helianthemum species [H. almeriense pau, H. appeninum.,H. cinereum, H. hirtum, H. marifolium, H. nummularium, H. syriacum, H. squamatum], all cistaceae species from the mediterranean region, was studied after seed storage in liquid nitrogen (Ln, -196C) for four months. In all samples assayed, mechanical scarification of the seed coat was carried out to enhance seed germination. For most samples studied, final germination percentages were unaffected by storage of seeds in Ln, both for intact seeds and for scarified seeds. The germination rate of cryopreserved seeds, expressed as days to reach 50 percent of the final germination percentage, was lower only for four samples of intact seeds and for three samples of scarified seeds. Therefore, this study shows that seed cryopreservation could be a suitable procedure for the long-term seed conservation of several Halimium and Helianthemum species.