One-step fitting of seed viability constants for two Australian plant species, Eucalyptus erythrocorys (Myrtaceae) and Xanthorrhoea preissii (Xanthorrhoeacea)

Long-term ex-situ seed storage under controlled conditions in gene banks has become an important tool for conserving threatened Australian plants; however, there is scant information about the seed longevity of most species. The aimofthepresentstudywastodeterminewhethertheseedlongevityoftwocontrastingAustralianspeciescouldbemodelled using the seed viability equation, and whether the universal temperature constants are applicable to these species. Seeds of Eucalyptus erythrocorys F.Muell. (Myrtaceae) and Xanthorrhoea preissii Endl. (Xanthorrhoeaceae) were aged at moisture contents ranging from 3.9 to 15.7% and temperatures between -20 and 60 � C. Survival data were fitted to the seed viability equation in one step and the species constants for each species determined. Both E. erythrocorys and X. preissii seeds exhibitedorthodoxseedstoragebehaviourwhoselongevitycouldbemodelledusingtheseedviabilityequation.Theviability constants were KE=8.81, CW=4.97, CH=0.0412 and CQ=0.000379 for E. erythrocorys and KE=8.77, CW=5.29, CH=0.0382 and CQ=0.000473 for X. preissii. The universal temperature constants could not be used without a significant increase in error. The storage behaviour of these two Australian species is in keeping with that of orthodox species from around the world. Predictions are that E. erythrocorys will be long-lived under gene bank conditions, whereas X. preissii would be moderately long-lived. Current long-term gene bank storage conditions appear suitable for storage of these species; however, recommendations for short-term storage need to be re-evaluated. Received 24 June 2012, accepted 22 October 2012, published online 21 December 2012