Poplar breeding and testing strategies in the north-central U.S.: Demonstration of potential yield and consideration of future research needs

Abstract

We present results from a Populus Regional Testing Program that has been conducted in Minnesota, Iowa, Wisconsin, and Michigan over the past six years. Our objectives have been to: 1) identify highly productive, disease resistant intra-and inter-specific clonal selections and 2) understand patterns of genotype x environment interactions within the region that would, logically, govern commercial deployment of new clones. Clones were developed by breeding and selection programs at the University of Illinois, Iowa State University, University of Minnesota, and the USDA Forest Service for experiments established in 1995. We report results of analyses of variance and principal component analyses of tree diameters and estimated above-ground biomass that demonstrate significant genotype main effects and significant genotype x environment interactions. Maximum mean annual above-ground biomass increments have surpassed 16 Mg ha-' y-', exceeding previously reported yields of poplars grown under similar conditions in the north-central U.S. We also discuss the breeding and selection of poplars in general with specific attention to regional research needs.

Specific Gravity of Hybrid Poplars in the North-Central Region, USA: Within-Tree Variability and Site × Genotype Effects

“…Fifteen of the seventeen sites for the current study were selected from two regional networks of hybrid poplar clone and yield trials established in the north-central United States during 2000 to 2001 (10-year-old plantations) [27,37] and 1988 to 1991 (20-year-old plantations) [38][39][40]. The remaining two sites (15-year-old plantations) were established in 1995 as part of the woody biomass feedstock development program at Iowa State University (Figure 1).…”

“…Although yield has been the primary focus of most hybrid poplar tree improvement programs [8,27], the aforementioned benefits of specific gravity for multiple end uses have ensured it has remained one of the key traits during breeding. One of the challenges during selection is the relationship between specific gravity and position along the bole of the tree, which has been somewhat inconsistent with tree age, site, and genotype [26,[28][29][30].…”

Age trends in genotypic variation of wood density and its intra-ring components in young poplar hybrid crosses

“…Despite numerous reports on wood density changes within trees from bark to pith and on genotypic variation of wood properties in poplar hybrids at different ages, there is very limited information on changes of genotypic variation, heritability, and genotypic correlations of wood density with age or with distance from pith to bark. Some preliminary indications are given only by Riemenschneider et al [41]. Early selection based on use of young progenies for predicting mature wood density requires knowledge of juvenile-mature wood density relationships.…”

Evaluation ofPopulusandSalixContinuously Irrigated with Landfill Leachate II. Soils and Early Tree Development

“…First, DN Populus clones performed similarly when irrigated with leachate or water. Recently, researchers have reported below-average growth performance (i.e., rooting, diameter, and height) of traditional DN genotypes such as clones DN34 and DN182 (Riemenschneider et al, 2001;Zalesny and Wiese, 2006;Zalesny et al, 2005a), which has led to the consideration of less deployment of these DN clones, especially in the North Central United States. However, the results of the current study were important because, along with phytoremediation capabilities (Zalesny and Bauer, 2007) and promising results from recent breeding efforts (Neil Nelson, USFS NCRS, William Berguson, University of Minnesota NRRI, personal communication) DN clones appear to be suitable genotypes for the cleanup of leachate with similar contaminant levels and, possibly, of other contaminants.…”

“…Given a general lack of differences for height, volume, and root dry mass, these observations must be interpreted cautiously. Generally, clones NM2 and NM6 have performed similarly for above-and below-ground traits (Riemenschneider et al, 2001;Zalesny and Wiese, 2006;Zalesny et al, 2003). Researchers have selected and utilized both clones almost interchangeably.…”