Effects of conifer wood biochar as a substrate component on ornamental performance,photosynthetic activity,and mineral composition of potted Rosa rugosa

A greenhouse experiment was conducted to assess the performance of biochar obtained from pyrolysis of conifer wood as a substrate component for growing potted Rosa rugosa plants. Rose plants were grown with different mixtures of sphagnum peat and biochar (100% peat, 75% peat–25% biochar, 50% peat–50% biochar, 25% peat–75% biochar; v:v). Increasing the biochar content from 25% to 75% increased the air content, bulk density, electrical conductivity, and K and Na concentration in the substrates. The addition of 25% biochar to the substrate showed promising potential for R. rugosa when compared with 100% peat given the similar growth performance, water-use efficiency, and ornamental quality (number of flowers and leaf colour). The Ca and Na concentrations in leaves and roots as well as the Mg content in roots increased as the biochar percentage in the substrate increased, whereas an opposite trend was observed for P and K concentrations. The best performance and ornamental quality of R. rugosa grown with 100% peat and 75% peat–25% biochar compared with 50 and 75% biochar treatments were attributed to a higher degree of photosynthesis, Soil Plant Analysis Development index, and pigment content. Overall, adding 25% of conifer wood biochar as a substrate component could be applied for economic purposes without detrimental effects on the yield and quality of potted roses.