Sow what? Assessing quality, genetic diversity and thermal germination responses in a climate-smart native seed production

Accelerating biodiversity loss is driving unprecedented demand for habitat restoration and reliable supplies of genetically diverse native seed. Seed Production Areas (SPAs) aim to meet this demand, yet cultivation under managed conditions may alter seed quality and genetic composition. We assessed seed quality, genetic diversity, and thermal-germination responses of Maireana brevifolia from wild populations and from first-generation SPA seed within a production system that integrates populations from three provenance zones: local (to the restoration area), southern (cooler, wetter), and future climate-adjusted (hotter, drier). We quantified seed weight, seed viability (fill/empty/damaged) via X-ray, and germination in greenhouse trials and incubators. Using SNP genotyping, we calculated multilocus heterozygosity (MLH) for wild plants, SPA maternal plants, and SPA progeny, and determined mother-offspring genetic distance through identity-by-state (IBS). Wild seed was heavier and had higher fill rates than SPA seed. Germination differed strongly among provenances and within the SPA. Offspring MLH exceeded maternal MLH (p < 0.001). In wild populations, mean MLH was positively associated with higher seed weight; in SPA plants, higher maternal MLH correlated with higher germination. Our findings show that mixed provenance seed producing can increase genetic diversity and highlight the value of incorporating genomic monitoring alongside seed trait assessments to track genetic diversity, detect potential bottlenecks during seed production, and benchmark genetic change across generations by comparing wild, founder (F0), and SPA-produced seed.