Abstract
Varietal differences in root development were evaluated using cuttings of three species and four cultivars of evergreen azaleas. More than 80% of cuttings were rooted in a shaded rain shelter, a closed-frame and a mist propagation system. Total root lengths of Rhododendron ripense and R. × pulchrum ‘Oomurasaki’ were long, while those of R. indicum ‘Osakaduki’ and Kurume azalea ‘Kirin’ tended to be short. Leaf number and leaf area of each azalea were increased in cuttings of shaded rain shelter and closed-frame system, compared to mist propagation system except for the leaf area of R. macrosepalum. R. macrosepalum, R. indicum ‘Osakaduki’ and R. × mucronatum ‘Shiro-ryukyu’ showed a wide rooting areas in the cuttings, having many and a wide range of extended roots out of cylindrical net in the nursery bed. R. kaempferi and Kurume azalea ‘Kirin’ showed a narrow rooting area, having a small number of roots extending out of the net. These varietal differences of root characteristics in rooted cuttings showed the same tendency as field-planted plants in a previous study and would be related to genetic traits originating from adaptation to the natural habitat environment by each original species and the varieties derived from them. Root characteristics of cuttings from evergreen azalea can be indicator of the root traits of field plants and would be useful information for application to the breeding of evergreen azalea.
