Effectiveness and economic viability of native seed pelleting in large-scale seedling production for revegetation

Revegetation efforts in the context of ecological restoration require large numbers of nursery grown seedlings across a wide range of native species. Automated seeding production lines in nurseries struggle to handle low quality small-seeded species, often resulting in under or over-seeding which increases production costs by requiring manual sorting or thinning. A combination of seed processing and testing can improve seed quality, while seed pelleting can increase and standardise seed size, shape and weight, allowing for more homogenous seed delivery. In this study, we tested the effect of seed pelleting on seeding consistency and seed-to-seedling conversion rates for ten small-seeded Australian native species belonging to the Myrtaceae family. A break-even model was developed using seed and seedling production parameters and costs to explore the economic viability and benefits of seed pelleting for large-scale nursery seedling production. More than one million seedlings were produced for this study in a commercial native plant nursery and used in Eucalyptus woodland revegetation projects in the Wheatbelt region of Western Australia. Our results showed that seed delivery consistency was significantly improved in nine out of ten species, and seed-to-seedling conversion rates increased in eight species. The break-even analysis indicated that, on average, seed pelleting becomes economically viable for production targets above 38,287 seedlings. Given the average seedling production target of 100,985 seedlings per species, this could yield an average saving of $1459 per species. The enhanced efficiency in large-scale seedling production allows for more cost-effective revegetation and can help redirect resources to include a wider range of challenging native species that so far have been underutilised in restoration due to logistical constraints.