4가지 옥상녹화용 인공배합토에서 3종의 상록활엽관목 생육특성 평가

Plant Growth Assessment of 3 Species Evergreen Broad-leaved Shrubs in 4 types Green Roof Substrates

As evergreen broad-leaved shrub, Raphiolepis indica var. unbellata (Thunb.) Ohashi, Nandina domestica Thunb., Rhododendron indicum Sweet. were selected and assessed with 4 type green roof substrates: perlite small grain(PS), perlite small grain+field soil (sandy loam)(v/v, 2:1)(PSFS), cera-soil(CS), and cera-soil+field soil (v/v, 2:1)(CSFS). All the substrates could be used for intensive green roof system as well as extensive green roof system once the bulk density and field capacity were considered. All the substrates became acidified over time. A year after the experimental plots establishment, PS and PSFS were at the proper range of Soil pH, but CS and CSFS still showed alkalinity. All the substances became sterile and were concluded that these substrates will suppress the plant growth. After 6 months of the establishment, there was no significant difference among the shrubs grown in the substrates and field soil. However, all the shrubs after a year of the establishment became worse compared to those after 6 months. Also there were significant differences between 3 species shrubs with 4 type substrates after a year of the establishment. In the concrete, Raphiolepis indica var. unbellata (Thunb.) Ohashi showed relatively higher growth in CS and CSFS than the others. Nandina domestica Thunb. showed lower growth in all the substrates than field soil. Rhododendron indicum Sweet. showed relatively higher growth in PS and PSFS than the others. The results indicate that the assessment of different green roof substrates is required for the healthy growth of evergreen broad-leaved shrubs. Thus, the application of different evergreen broad-leaved shrubs on green roof system requires the assessment of different green roof substrates for each one and also annual maintenance of fertilization.