Aspen improvement strategies for western Canada — Alberta and Saskatchewan

Abstract

A breeding plan was developed for improving trembling aspen (Populus tremuloides) and aspen hybrids for fiber and wood production in Alberta and Saskatchewan. Phenotypic selections are being made from three major geographic regions, northern Alberta (55°-57° N, 114°-120° W), southern Alberta (53°-55° N 114°-120° W), and East-central Alberta and western Saskatchewan (54°-56° N, 107°-114° W). The initial breeding population will include 150 phenotypically selected individuals, 50 from each of the three regions. Open-pollinated seed will be collected and a provenance study will be established to examine the genetic variation in growth and adaptability across the regions. A simple recurrent breeding program for general combining ability will be implemented to improve pure trembling aspen. Initial breeding will be done within each of the three geographic regions until provenance information is available. A nested polycross mating design will be implemented to evaluate the selected parents and generate new breeding materials. Based on early measurements in progeny tests, outstanding parents will be selected to produce planting stock for operational planting. Selections for second generation breeding will be made at age 10 after wood quality and disease resistance can be evaluated reliably. A combined family- and within-family selection will be used to form a new breeding population. The initial focus of the hybrid breeding program will be to identify the interspecfic aspen hybrids that are suitable for planting in northern latitudes. Hybridization will concentrate on crosses between the local trembling aspen and northern sources of P. tremula and P. davidiana. Key words: aspen selection, breeding, hybridization, P. tremuloides, P. tremula and P. davidiana

Genetic parameters of growth and adaptive traits in aspen (Populus tremuloides): Implications for tree breeding in a warming world

“…Score 0 was recorded for dormant buds, score 1 indicated a swollen bud, score 2 indicated broken bud scales, score 3 was given for the emergence of green leaves, score 4 indicated leaf extension, score 5 indicated more than two leaves emerged, and score 6 indicated fully unfolded leaves. Scores were recorded for each individual tree on April 12,20,22,24,26,May 1,3,9,11,13,15,17,19 For leaf senescence scores, scoring was based on an eight-level scale according to Fracheboud et al [26]. Score 0 represented uniformly green leaves, score 1 indicated darker than pale green leaves, score 2 indicated a majority of pale green leaves, score 3 indicated more green than yellow leaves, score 4 indicated a majority of yellow leaves, score 5 indicated only yellow leaves, score 6 indicated 20% brown leaves, score 7 was 50% leaf abscission, and score 8 represented �90% leaf abscission.…”

Wood Quality and Growth Characterization across Intra- and Inter-Specific Hybrid Aspen Clones

“…Previously in the United States, P. tremuloides and P. tremula crosses demonstrated improved growth, form, and wood quality; while, P. tremuloides and P. davidiana crosses had superior growth characteristics on relatively poor and dry sites [12]. Using a similar strategy, it was postulated that similar results could be achieved in Canada, if the appropriate inter-specific crosses of parent trees from northern European countries such as Finland and from north-eastern China were employed [19].…”

Growth and phenology of hybrid aspen clones (Populus tremula L. x Populus tremuloides Michx.)

“…Interspecifi c hybrids have grown faster than the progenies of intraspecifi c crosses (Heimburger 1936, Einspahr and Benson 1964, Melchior and Seitz 1966, Heimburger 1968, Zsuffa 1969, 1973. There is much genetic diversity in aspen, and it can be manipulated through selective breeding, interspecifi c hybridization and cloning (Li 1995).…”