Quantitative Genetic Analysis of Adventitious Root Forming Ability in Populus trichocarpa (Torr Et. Gray)

Abstract

The ability of poplars (Populus sp.) and poplar hybrids to form adventitious roots is critical to the commercial deployment of intensively cultured poplar plantings, because the propagule of choice for such plantings is an unrooted dormant hardwood cutting. Given the importance of rooting ability, it is difficult to explain the shortage of quantitative genetic understanding of rooting compared to other commercially important traits. One reason for the aforementioned lack of knowledge is that genetic selection for rooting ability is mostly applied incidentally during serial propagation between stages of field testing for growth potential and disease resistance. Clones that root poorly are automatically eliminated from the testing process. However, such incidental selection provides little knowledge about selection efficiency, or possible correlated effects of selection for rooting ability, on other important traits. Likewise, incidental selection does not lead to the identification of more easily evaluated above-ground traits that could be used as indirect selection criteria for rooting ability.