Critical review of threatened species collections in the New South Wales Seedbank: implications for ex situ conservation of biodiversity

Abstract

This article reviews the germinability and viability of seeds of threatened species collections in the New South Wales (NSW) Seedbank with the manifold aims of: ensuring that existing storage treatments and conditions provide effective ex situ storage of threatened species seed; providing baseline viability and seed storage life data on threatened species; and, identifying research gaps in seed germination and storage protocols for threatened species and communities. The germinability and viability of a range of seed accessions, of various ages and stored under different (although mainly identifiable) conditions in the NSW Seedbank, was determined through germination and cut-tests. The results indicated that many of the Fabaceae, Myrtaceae and Proteaceae species tested are orthodox and can be stored at 5 to 10% moisture content at 5°C for up to ten years without significant loss of viability (short- to medium-term storage). The best results were obtained in the lower seed moisture content range (2 to 9%), which appeared to be especially critical for long-term storage of many Proteaceae accessions, reinforcing the need to attain the correct seed moisture content for long-term storage. Around 10% of accessions exhibited some degree of dormancy even after long storage periods. Storage of the widest range of species, for periods greater than ten years for long-term conservation purposes, is generally best conducted by storing at sub-zero temperatures. Freezing at -18°C had little effect on the germinability of a range of seeds tested and is recommended over storage at 5°C. Collection and seed banking procedures for the NSW Seedbank will be regularly reviewed and procedures modified in order to identify the best long-term storage conditions for species within this and other seedbanks. Seed collection strategies to maximize diversity and uses of seedbanks in conservation are discussed.