Investigating the Effect of Hydrafiber and Biochar as a Substitute for Peat-Based Substrate for Zinnia (Zinnia elegans) and Snapdragon (Antirrhinum majus) Production

Increasing environmental and economic concerns necessitate the research for peat moss alternatives, aiming to balance ecological sustainability with cost-effectiveness. This study assessed whether biochar (BC) and hydrafiber (HF) could be a partial replacement for peat moss as substrate components. Twelve substrates were formulated by either mixing BC (20%, 40%, and 60%, by vol.) with HF (20%, 40%, and 60%, by vol.), with the remaining being peat moss or mixing BC (0%, 20%, 40%, and 60%, by vol.) with the commercial substrates (CS) to grow zinnia (Zinnia elegans) and snapdragon (Antirrhinum majus) plants in containers. The physical properties of the substrates, including container capacity, total porosity, air space, bulk density, and chemical properties including leachate pH and electrical conductivity (EC) were measured. Plant growth parameters including growth index (GI) and leaf greenness (indicated with SPAD), biomass, and number of flowers were measured biweekly. The results showed all the substrate mixes had similar air space, bulk density, and SPAD. Treatment with 20% BC and 80% CS yielded the highest GI, biomass, and numbers of flowers in both zinnia and snapdragon. In conclusion, BC could be used to partially (20%) replace commercial substrate mix for container-grown zinnia and snapdragon.