Browsing by Subject "vegetative propagation"

The special forms of conifers have been a matter of interest due to their ornamental values for centuries all over the world. Special forms have traditionally been reproduced by vegetative means, mostly by cuttings or grafting methods. At present, the vast majority of ornamental coni-fers traded in Finland is imported from abroad. The winter hardiness of foreign taxa is often in-adequate, causing wasted work and expenses when plants have to be replaced after cold winters. The aim of this thesis was to find suitable propagation methods for special forms of our native conifers and in that way enhance their domestic production. The plant material used in this study included special forms of native Norway spruce (Picea abies (L.) Karsten) and juniper (Juniperus communis L.), common Norway spruce and eight foreign conifer taxa. The methods studied were propagation by stem cuttings and by grafting. The aim of the grafting experiment was to compare the healing of graft union in different genotypes of Norway spruce. In the cutting experiment the effects of genotype, age of the mother plant, position of cutting and treatment with a growth regu-lator on the rooting of conifer cuttings were studied. All of the genotypes of Norway spruce studied were successfully grafted and formed a perfect graft union. For aesthetic reasons propagation by cuttings may still be more suitable for at least dwarf conifers. Genotype had a very significant effect on the rooting of coniferous cuttings. Cut-tings from a juvenile special form of Norway spruce rooted better than those taken from adult trees. Generally, the position of cutting did not significantly affect rooting of special forms of Norway spruce. In one colour form, however, cuttings obtained from the juvenile lower part of the stock tree rooted far better than cuttings taken from the top of the same tree. Treatment with in-dolebutyric acid had a negative effect on the rooting of Norway spruce and juniper, but no signifi-cant effect on the cuttings of foreign conifer taxa. Introducing special forms of native conifers would add to the diversity of home gardens and public parks in a sustainable way. To advance commercial production of native selections we need to pay regard to the rooting ability of the special forms, not only their appearance. It is cheaper to reproduce the special forms by cuttings than by grafting methods. Plants produced by cuttings also have more stable growth habit than grafts do, which is especially important for dwarf conifers.