Effective storage of highly germinable seeds of poisonous Pimelea species for future research

Abstract

Some ephemeral Pimelea species are poisonous and cause many livestock deaths in Australia. Research into pimelea poisoning has been episodic and unavailability of viable seeds hampers research. Hence, long-term storage of good quality Pimelea seeds would be valuable. Seeds of five species of poisonous Pimelea were stored under four differing regimes and their germinability assessed over nearly six years. Initial seed viability was mostly high (> 70%) but appreciable germination was only achieved when gibberellic acid was included in the germination substrate. Well-dried seeds stored under vacuum in sealed, laminated, aluminium foil sachets in a laboratory (at approximately 22°C) lost some dormancy after two years and maintained viability levels above 60% for 68 months. Cool storage (5°C) without complete atmospheric moisture exclusion and laboratory storage in screw-top plastic bottles resulted in very low germinability after 30 – 45 months. Seeds stored at -20°C in identical plastic bottles maintained fair germinability over 68 months but results were seed lot-specific (0 – 74%). Loss of germinability seemed due mostly to increasing seed moisture content rather than storage temperature but other unidentified factors were involved. Plastic laboratory-grade sample bottles with screw-top lids proved to be unsuitable storage containers for maintaining viable seeds of Pimelea.