Tolerance of crop seeds to cooling and storage in liquid nitrogen (-196 C).

Abstract

Storage in liquid nitrogen (LN2) has the potential of providing indefinite preservation of seed germplasm. Determining the tolerance of seeds of a given species and/or cultivar to LN2 cooling and subsequent rewarming is the first step in establishing the feasibility of LN2 storage. Seeds of 29 crops were directly exposed to LN2 (-196 C) for periods up to 180 days. Of all species ex posed, only sesame (Sesamum indicum L.) and flax (Linum usitatissimum L.), indicated any loss of viability after LN2 storage. Damage to sesame seeds was reflected by increased seedling abnormalities (stubby roots), which appeared to be associated with the cooling/rewarming cycle. Flax seeds were physically damaged (cracking of the seed coat and embryonic tissue) resulting in reduc ed germination. Survival of the selections during LN2 cooling and rewarming and a lack of damage to seed viability during extended storage strongly supports the