Overcoming limitations to propagation from seed of 40 Australian species important for restoration

Abstract

<p>High standards in managing the seed-supply chain, emphasizing sourcing and seed storage, are crucial to maintaining seed viability and ultimately to meeting restoration goals. The germination of 40 plant species was investigated in response to difficulties experienced by restoration practitioners in propagating them from seed in nurseries and in direct seeding. The species were from a biodiversity hotspot in inland eastern Australia and spanned a range of life-forms. The initial constraint identified was poor seed viability, which varied widely within and between species but was <50% in at least one seedlot of 36 species. Low seed viability was indicated by poor seed storage and processing practices, manifest in excessive storage time, herbivory, fungal infection, and inadequate seed collection and processing (e.g. collection of immature seed and overcleaning). The main reason for low germination of viable species was seed dormancy. Dormancy was identified in 16 species: pre-sowing treatments in these species were effective in relieving dormancy or increasing germination percentage by two to three-fold. The most frequent pre-sowing treatment required was scarification. Stratification, de-husking and leaching also increased germination in some species. Temperature conditions for high germination were also investigated. Seasonal temperature treatments affected germination in 22 species. The results emphasize the necessity for (1) testing seed before use" (2) identifying temperature ranges to achieve maximum germination" (3) identifying species with germination constraints, and (4) using suitable pre-sowing treatments for plant propagation in nurseries and potentially in the field.</p>