DIFFERENTIAL RESPONSES OF BETULA COSTATA AND B. SCHMIDTII SEEDLINGS TO SOIL SUBSTRATE AND FERTILIZATION REGIMES: IMPLICATIONS FOR EFFECTIVE SEEDLING PRODUCTION

We investigated the effects of substrate × fertilization regimes on the growth and nutrient uptake of Betula costata and B. schmidtii seedlings. They were subjected to two soil treatments, i.e., pure artificial substrate and a mixture of artificial substrate and sand-masato, and five fertilization treatments, i.e., liquid fertilizer (LF, Fert1), Controlled-Release Fertilizer (CRF) in summer (Fert2), CRF in summer and fall (Fert3), long-term CRF (Fert4), and CRF + LF (Fert5). We measured growth parameters (the Root Collar Diameter (RCD), height (HT), and biomass allocations) and foliar nutrient concentrations and analyzed changes in soil chemical properties. B. costata and B. schmidtii responded differently to soil and fertilization regimes and the growth pattern did not follow the quantity of total nutrient input in this study. Overall, B. costata preferred the mixed soil and responded sensitively to different fertilization regimes but B. schmidtii did not. The total biomass of B. costata seedlings was the largest in the combination of CRF and LF (Fert5). B. schmidtii seedlings yielded similar biomass to all treatments except Fert1. The highest foliar N concentration was found in Fert4 and the lowest in Fert1 and Fert2 for B. schmidtii; there was no significant effect of either soil or fertilization regimes on foliar N concentration in B. costata. The CRF + LF (Fert5) treatment was compatible for B. costata but not for B. schmidtii. Therefore, this study implies that seedlings can be effectively produced through appropriate soil and fertilization methods suitable for each species’ traits rather than increasing nutrient supply.