Abstract: To explore the substrate and environmental conditions more suitable for cultivating Alnus formosana seedlings, seedling substrate was prepared with red core soil, coconut bran, controlled release fertilizer, organic fertilizer and calcium magnesium phosphate fertilizer, and potted seedlings of Alnus formosana were cultivated under different shade conditions. The results showed that the seedling height, ground diameter, Pn, Gs and Tr of Alnus formosana seedlings all showed a light transmittance of 40%>100%>15%, Ci showed a light transmittance of 15%>100%>40% under different shading conditions. The addition of coconut bran in seedling substrate was more beneficial to the improvement of seedling height, diameter and Pn of Alnus formosana. The effects of different fertilizers on Alnus formosana were different under different shading conditions. All fertilization treatments showed that organic fertilizer > slow release fertilizer > calcium magnesium phosphate （fertilizer） under the condition of 40% and 100% light transmittance. Slow release fertilizer could promote the growth of Alnus formosana, but organic fertilizers do not work better under the condition of 15% light transmittance. The optimal treatment for cultivating Alnus formosana seedlings was 40% light transmittance +69.2% red mud +30% coconut bran +0.8% organic fertilizer.

Key words: Alnus formosana, seedling substrate, shading, seedling, fertilization