Effects of shading and fertilizer treatments on the growth characteristics of Chamaecyparis obtusa (S. et Z.) Endlicher seedlings

Abstract Chamaecyparis obtusa is increasing the main reforestation species in the warmer southern part of the Republic of Korea because of its resistance to climate warming and economic value for timber. In this study, we investigated the growth response of Chamaecyparis obtusa 2-0 container seedlings to combined artificial shading (full sunlight, 35%, 55%, and 75%) and fertilization (no fertilization, 0.5 g/L, 1.0 g/L 1.5 g/L, 2.0 g/L, 3.0 g/L) treatments. Seedlings treated with 1.0 g/L fertilization and in full sunlight condition showed the highest height growth while seedlings treated with 0.5 g/L fertilization and in full sunlight condition showed the highest growth of root collar diameter. Seedlings treated with 1.0 g/L fertilization and in full sunlight condition showed the highest total dry weight while those treated with 0.5 g/L, 1.0 g/L and 1.5 g/L fertilization and in full sunlight condition and 0.5 g/L fertilization in 35% artificial shading showed the highest Height/Root collar diameter ratio. In addition, seedlings treated with 1.0 g/L fertilization and in full sunlight condition showed the highest seedling quality index. In general, the fertilization treatment effects on seedling growth characteristics were appreciably significantly different across the shading treatment conditions. The magnitude of the differences in the interaction effect of the fertilization treatments is higher in lower than in higher shading treatment conditions. The results suggest that 1.0 g/L seedling fertilization growing in full sunlight condition is the most appropriate nursery treatment level for producing superior quality Chamaecyparis obtusa 2-0 container seedlings. The suggested optimum artificial shading and fertilizer treatments level can be used as preliminary data for producing superior seedlings Chamaecyparis obtusa 2-0 container seedlings capable of achieving sustained reforestation and landscape restoration success in the southern part of the Republic of Korea and similar locations with warming climatic and conditions.