%0 Articles
%T Multiplication of hybrid aspen (<em>Populus tremula</em> L. x <em>P. tremuloides</em> Michx.) from cuttings
%A Niina, Stenvall
%D 2006
%J Dissertationes Forestales
%V 2006
%N 33
%R doi:10.14214/df.33
%U http://dissertationesforestales.fi/article/1816
%X The primary aim of the present study was to find an efficient and simple method of vegetative propagation for producing large numbers of hybrid aspen (<em>Populus tremula</em> L. x <em>P. tremuloides</em> Michx.) plants for forest plantations. The key objectives were to investigate the main physiological factors that affect the ability of cuttings to regenerate and to determine whether these factors could be manipulated by different growth conditions. In addition, clonal variation in traits related to propagation success was examined. According to our results, with the stem cutting method, depending on the clone, it is possible to obtain only 1&#8722;8 plants from one stock plant per year. With the root cutting method the corresponding values for two-year-old stock plants are 81&#8722;207 plants. The difference in number of cuttings between one- and two-year-old stock plants is so pronounced that it is economically feasible to grow stock plants for two years. There is no reason to use much older stock plants as a source of cuttings, as it has been observed that rooting ability diminishes as root diameter increases. Clonal variation is the most important individual factor in propagation of hybrid aspen. The fact that the efficiently sprouted clones also rooted best facilitates the selection of clones for large-scale propagation. In practice, root cuttings taken from all parts of the root system of hybrid aspen were capable of producing new shoots and roots. However, for efficient rooting it is important to use roots smaller than one centimeter in diameter. Both rooting and sprouting, as well as sprouting rate, were increased by high soil temperature; in our studies the highest temperature tested (30ºC) was the best. Light accelerated the sprouting of root cuttings, but they rooted best in dark conditions. Rooting is essential because without roots the sprouted cutting cannot survive long. For aspen the criteria for clone selection are primarily fiber qualities and growth rate, but ability to regenerate efficiently is also essential. For large-scale propagation it is very important to find clones from which many cuttings per stock plant can be obtained. In light of production costs, however, it is even more important that the regeneration ability of the produced cuttings be high.