Preservation of Quercus robur L. Embryonic Axes in Liquid Nitrogen

Abstract

Seeds of pedunculate oak show ‘recalcitrant’ seed storage behaviour and cannot be stored for more than three winters without loss of germinability. The aim of the experiments was to find out whether it is possible to protect excised oak embryonic axes from injuries caused by partial desiccation and freezing in liquid nitrogen (LN2). Embryonic axes were sterilized, cryoprotected, coated with calcium alginate, slowly dehydrated to 24% moisture content (fresh weight basis) and finally frozen, first slowly to -20°C and afterwards rapidly to -196°C. After rewarming (at 40°Q and 3 weeks of in vitro culture survival of the embryonic axes was assessed. After exposure of embryonic axes to LN2 (-196°C) the following results were obtained: 4% of embryonic axes with growing shoot, 8% with growing root, 0% with growing shoot and root, 78% of axes producing callus, 6% of greening embryonic axes without shoot and root growth, so the total survival was 96%. Regeneration of plants from LN2-treated embryonic axes is, however, impossible because so few surviving embryonic axes had a growing shoot and none had growing shoots and roots.