S05 - Session P2 - Effects of IBA and cold treatments on rooting from hardwood and softwood cuttings in Wisteria species

Authors: Sadasue Shunsuke *, Yuki Mizunoe, Yukio Ozaki

Wisteria species are woody plants distributed in East Asia and North America, and the cultivars bear highly ornamental racemes in spring season. In commercial production, Wisteria cultivars are usually propagated vegetatively, i.e., grafting and cutting. The fundamental information about factors affecting the vegetative propagation efficiency is still insufficient. The aim of this study is to assesses the effect of plant growth regulator and cold treatments on rooting from hardwood and softwood cuttings. Eighteen and five cultivars were supplied for hardwood and softwood cuttings, respectively, from four Wisteria species: namely, W. floribunda , W. brachybotrys , W. sinensis and W. frutescens . Hardwood branches were sampled in March, and prepared for cold treatment at 5℃ for 0 and 2 months. Thereafter, the hardwood cuttings were immersed with and without indole-3-butyric acid (IBA) solution. Newly elongated branches were sampled in June and prepared as softwood cuttings. They were immersed with and without IBA solution. Hardwood and softwood cuttings were planted into red clay soil in plastic container, and grown at 20℃, under 70% relative humidity and natural light in phytotron. Irrigation was conducted every two days. Number of rooted cuttings and length of the longest root were investigated 90 days after planting. Rooting rates of hardwood cuttings sampled from W. floribunda , W. brachybotrys and W. sinensis were low, regardless of cultivar and treatment. Varietal difference of rooting rate was recognized in soft wood cuttings of W. floribunda. In W. brachybotrys and W. sinensis , rooting was recognized in softwood cuttings treated with IBA. W. frutescens showed high ability of rooting and elongation in all treatments and in both hardwood and softwood cuttings. This study demonstrates that reproduction and growth of the roots are greatly affected by genotypes and sampling season.