Peat extraction for nursery substrates contributes to carbon emissions and peatland destruction, highlighting the need for sustainable alternatives such as biochar. In this study, we evaluated how biochar substitution of peat (0–100% by volume) combined with four fertilizer rates (0, 0.5 × , 1 × (standard), 2 ×) affected seed germination, seedling survival, total seedling biomass, root-to-shoot biomass ratio (RSR), and CO₂ flu...