Improved Planting Stock Research Articles

Genotyping SNPs in lignin biosynthesis gene (CAD1) and transcription factors (MYB1 and MYB2) exhibits association with wood density in teak (Tectona grandis L.f.).

Teak (Tectona grandis L.f.), an important source of tropical timber with immense economic value, is a highly outcrossing forest tree species. 150 unrelated accessions of teak (Tectona grandis L.f.) plus trees assembled as clones at National Teak Germplasm Bank, Chandrapur, Maharashtra, India was investigated for association mapping of candidate lignin biosynthesis gene (CAD1) and transcription factors (MYB1 and MYB2). The CAD1, MYB1 and MYB2 were amplified using specifically designed primers. The amplified sequences were then sequenced and genotyped for 112 SNPs/11 indels. We evaluated the association between SNPs and wood density in teak accessions using GLM and MLM statistical models, with Bonferroni correction applied. The teak accessions recorded an average wood density of 416.69kg.m-3 (CV 4.97%) and comprised of three loosely structured admixed sub-populations (K = 3), containing 72.05% genetic variation within sub-populations with low intragenic LD (0-21% SNP pairs) at P < 0.05 and high LD decay (33-934bp) at R2 = 0.1. GLM and MLM models discounting systematic biases (Q and K matrices) to avoid false discovery revealed five loci at rare variants (MAF 0.003) and three loci at common variants (MAF 0.05) to be significantly (P < 0.05) associated with the wood density. However, the stringent Bonferroni correction (4.06-7.04 × 10-4) yielded only a single associated locus (B1485C/A) from exon of MYB1 transcription factor, contributing to about 10.35% phenotypic variation in wood density trait. Scored SNP locus (B1485C/A) can be developed as a molecular probe for selection of improved planting stock with proven wood density trait for a large-scale teak plantation.

Height growth patterns of genetically improved Scots pine and silver birch

Abstract The breeding of forest tree species in the Baltic region has notably contributed to wood production for the bioeconomy. Growth modelling is used for long-term estimates of forest development. However, usually based on data from unimproved stands, they may underestimate the growth of improved trees. Accordingly, it is important to identify and integrate the altered stand dynamics associated with improved planting stock into existing growth models to accurately capture the resulting gains or, alternatively, develop new functions specifically designed for improved trees. We used the generalized algebraic difference approach to model and analyze height growth patterns of Scots pine and silver birch with different genetic improvement levels (improved forest reproductive material categories ‘qualified’ and ‘tested’). Modelling was based on 14 260 and 55 926 height–age series from open-pollinated progeny trials in Latvia and Lithuania with an age range of 3–46 and 5–22 years for pine and birch, respectively. Dynamic generalized algebraic difference approach forms of commonly applied height growth functions with forest reproductive material-category-specific sets of coefficients were tested. The dynamic form of the Chapman–Richards and King–Prodan equations had the best fit for Scots pine and silver birch, respectively. The expected height growth of the category ‘tested’ was slightly better than the one for ‘qualified’, with more distinct differences in silver birch. The model with forest reproductive material-category-specific coefficients reflected the actual growth of improved trees; however, such application is limited to sites with medium and high site indices, where improved planting stock is typically used. We recommend the model for young stands up to the age of 20 and 40 years for pine and birch, respectively, considering the empirical data cover on which the functions are based. A unified dynamic height model with the same functional form but category-specific parameterization for different improvement levels allows a practical applicability and effective communication amongst diverse users, thereby promoting the utilization of the model amongst forest owners and managers who possess information regarding the origin of planting stock.

Metadata analysis indicates biased estimation of genetic parameters and gains using conventional pedigree information instead of genomic-based approaches in tree breeding

Forest tree improvement helps provide adapted planting stock to ensure growth productivity, fibre quality and carbon sequestration through reforestation and afforestation activities. However, there is increasing doubt that conventional pedigree provides the most accurate estimates for selection and prediction of performance of improved planting stock. When the additive genetic relationships among relatives is estimated using pedigree information, it is not possible to take account of Mendelian sampling due to the random segregation of parental alleles. The use of DNA markers distributed genome-wide (multi-locus genotypes) makes it possible to estimate the realized additive genomic relationships, which takes account of the Mendelian sampling and possible pedigree errors. We reviewed a series of papers on conifer and broadleaf tree species in which both pedigree-based and marker-based estimates of genetic parameters have been reported. Using metadata analyses, we show that for heritability and genetic gains, the estimates obtained using only the pedigree information are generally biased upward compared to those obtained using DNA markers distributed genome-wide, and that genotype-by-environment (GxE) interaction can be underestimated for low to moderate heritability traits. As high-throughput genotyping becomes economically affordable, we recommend expanding the use of genomic selection to obtain more accurate estimates of genetic parameters and gains.

Examining the vulnerability of localized reforestation strategies to climate change at a macroscale

Climate change is altering the nature and condition of vast areas in the boreal forest of Canada. There are great uncertainties concerning impacts on the forest, along with how policy and economic responses will translate effectively between local and macroscales. In particular, planting tree seedlings with improved characteristics following harvesting is one localized response strategy considered essential by policymakers. However, planting costs limit the macroscale adoption of this strategy which may result in trade-offs between profitability and reducing vulnerability. In this study, we developed a decision support tool (called Q3) that links stand-level decision making to the macroscale and applied this model to investigate the financial attractiveness of planting improved stocks under one climate change threat, drought-induced seedling mortality. Using several scenarios describing planting effort, improved yields and risk to drought-induced seedling mortality, we showed that adopting improved planting stock strategies across a macroscale (i.e., the western Boreal forest of Canada) can be financially attractive when considering stand-establishment constraints and drought risk. In particular, a proactive approach can be less costly than a reactive approach to drought-induced seedling mortality. To maximize profits, the forestry industry would need to prioritize younger stands closer to processing mills that had a smaller percentage of conifer growing stocks prior to harvest. This research improves the linkages between macroscale policies and forest management activities critical for recommending future development paths that the forestry industry could follow to decrease climate change vulnerabilities.

A financial analysis of using improved planting stock of white spruce and lodgepole pine in Alberta, Canada: genomic selection versus traditional breeding

Genomics-assisted tree breeding (GATB) is an emerging biotechnology method that has the potential to produce improved planting stock in selected traits, such as greater volume or higher wood quality, more quickly and effectively compared with traditional field-based breeding (TB) methods. In this study, we conducted an ex-ante stand-level financial benefit-cost analysis that is linked to a provincial tree growth and yield projection model to investigate the potential financial benefits of using improved white spruce (Picea glauca (Moench) Voss) and lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) planting stock identified via alternative tree improvement strategies (i.e. GATB vs. TB methods) for forest companies in the province of Alberta, Canada. With consideration of major tree breeding and establishment costs, expected sawlog price premiums at harvest, a shorter breeding cycle time, and additional genetic gain in volume achieved from using the GATB method relative to the TB method in the financial analysis; this study found that the use of GATB-selected third-generation planting stock was difficult to justify economically alone compared with TB-selected seedlings under the current sawlog market value and the current planting rate with improved stock in the province. However, results of our sensitivity analysis also revealed that the GATB method is: (1) more financially supported at lower discount rates; (2) strongly supported through decreased seedling costs with increased areas planted with improved stock; and (3) strongly supported through an increase in log price premiums at harvest resulting from potentially better wood quality and higher volume production relative to TB-selected stock. The findings of this study highlight several important market and biophysical factors that forest managers should take into account when adopting biotechnology in forestry.

Climate change risk management in tree improvement programs: selection and movement of genotypes

Tree improvement programs usually consist of multiple breeding populations that target different climatic or ecological regions. Parent breeding material normally originates from and is deployed within the same breeding region, assuming optimal local adaptation of populations. Given the climate trends observed over the last several decades in western Canada, this assumption is unlikely to still be valid. This problem needs to be addressed either by delineating new deployment areas for improved planting stock or by selecting genotypes suitable for changed climatic environments. In a case study for white spruce, we analyzed height data from 135,000 trees grown in 44 genetic tests established and evaluated over a period of 35 years by industry and government agencies in Alberta. We show how the risk of planting maladapted trees can be minimized by moving planting stock to new areas, or by eliminating genotypes from breeding programs that are sensitive to anticipated future climate environments. Transfers that outperformed local sources consistently originated from locations with higher temperatures, suggesting north or northwest transfers. However, adaptation to cold appears to be a prevalent driver for genetic population differentiation in spruce, thus limiting how far material may be moved in current reforestation efforts to address future climate change.

Tissue culture production of hazelnut – disinfestation and impact of agar content

Australian hazelnuts are a new and emerging industry with the potential annual value in Tasmania alone estimated to be in the order of $ 10-15 million. Currently tree propagation is a slow and inefficient process with suckers collected from mature trees and grown on in nurseries. This parent material may harbour diseases and pests and surviving progeny may have inconsistent growth rates, undesirable suckering and non-uniform growth habits, making orchard establishment challenging. The development of tissue culture technologies for hazels has been pioneered in Oregon, USA, resulting in new cultivars and improved planting stock underpinning successful industry establishment in the USA. There has been little success with tissue culture production of local cultivars in Australia. This project examined strategies to optimise the transfer of glasshouse and field grown cuttings (explants) into axenic tissue culture, by testing different disinfestation treatments with sodium hypochlorite (NaOCl). Further, once in tissue culture, we tested the impact of varying agar content in media on key growth parameters. Outcomes indicated fungal and bacterial contamination from field-sourced explants was greater than those from glasshousesourced and that a greater NaOCl concentration (2.1% compared to 1.05%) was required to obtain axenic tissue cultures. Also, low agar content (0.2-0.4%) in tissue culture media produced improved hazel explant growth with greater shoot fresh weights and node numbers than with high agar content. These findings may help underpin the development of micro-propagation as a useful source of quality planting material for the hazelnut industry in Australia.

Planting rates and delays during the establishment of willow biomass crops

Biomass for bioproducts and bioenergy can be sourced from multiple sources. There is little information on commercial planting operations for willow biomass crops in North America. The objectives of this study were to evaluate the field capacities of two commercial machines (Step and Egedal Energy Planter) planting willow crops in northern New York State, determine the amount and distribution of delays. A study was conducted to evaluate planter activities. The two machines had similar mean field capacities (Cf) ranging from 0.89 to 1.14 ha h−1. Above-average rainfall in the later part of the planting season decreased Cf by over 20% for the Step planter from 1.14 to 0.91 ha h−1; largely due to delays in the headlands. Approximately 70% of the total delay time associated with the Step planter consisted of long-duration delays (>5 min) compared to 35% for the Egedal. Quality of planting stock was an issue for operations; undersized stems resulted in feeding issues. Several potential factors were identified for improved planting operations: loading stems and clearing feeding mechanisms at each turn, improved planting stock and quality control, improving machine design for wet conditions, and improved preparation for in-field repairs. In-field delays should be minimized to reduce demand on the crew and ensure a more uniform crop is established in the field.

A framework for testing radiata pine under projected climate change in Australia and New Zealand

Radiata pine plantation resources in Australia and New Zealand are a highly productive source of solid-wood and pulp products for domestic consumption and export. This has largely been achieved through long-term investments in tree breeding programs that select the best-performing genotypes for varied regional environments. However, climate change could threaten the realisation of genetic improvement in plantations due to suboptimal matching of improved planting stock to new climate conditions. Here, we investigate how information from genetic field tests could be utilised under anticipated climate change. We use principal component analysis and Mahalanobis distance measures to find the closest match between climate of plantation regions in the future and current climate of field test sites. By 2050, future climates of some important plantation regions are expected to match climates currently present in different regions. For example, future climates of Green Triangle, a key plantation region in Australia, will better match current climate of Western Australia. The Central North Island of New Zealand will shift to warmer and wetter climate with no current analogue, and Western Australia, to warmer and drier no-analogue climate. The latter is also likely to fall outside the climate niche where radiata pine can be grown in the future. Nevertheless, for the majority of radiata pine plantation regions in Australia and New Zealand our analysis provides a framework of how anticipated climate change can be addressed in tree improvement programs using existing field tests.

Progeny Test of Shorea Leprosula as Key Point to IncreaseProductivity of Secondary Forest in Pt Balik Papan ForestIndustries, East Kalimantan, Indonesia

Shorea leprosula is one of the valuable species in the tropical rain forest and it has distributed widely in the lowland tropical rain forest with altitude up to 700 m above sea level. Due to decreasingthe number of forest area, it will affect the sustainability of S. leprosula in the tropical rain forest. Ex situ conservation through establishment of S.leprosula progeny test was one of the best way to evaluate the best genotypes of mother trees (family) in order toset up the breeding program and produce the improved planting stock materials for forest rehabilitation.The research was conducted in Balik Papan Forest Industries (BFI), a Forestry Company in East Kalimantan, Indonesia. A total of 60 open pollinated plus trees have been selected and used for the genetic materials of the study. The progeny test wasplanted in 2009and laid out in randomized completely block design (RCBD), 4-tree line plots/family with 3 replications and at a spacing6 x 3 meter. The result of research showed significant in both high and DBH variable at tα Family5%. The biggest and lowest of DBH growth were the family no. 51018 (2.78cm.year-1 of mean annual increment/MAI) and family no. 51052 (1.66cm.year-1 of MAI). Moreover, the highest and the lowest of height growth were family 51030 (2.6 m.year-1 of mean annual increment/MAI) and 51003 (1.5 m.year-1 of MAI) respectively. Families selected in this research could be used to produce the improved planting stock material for rehabilitation insecondary tropical rain forest

Plant regeneration by somatic embryogenesis in Eucalyptus spp.: current status and future perspectives

Forest tree improvement programs benefit from the emergence of new biotechnological strategies that complement plant developmental biology and discovery of genes associated with complex multigenic traits. Recently, significant progress has been made in the area of plant regeneration via somatic embryogenesis (SE) for economically important tree species (e.g. pines). These advances have opened up new scenarios for deployment of new high-performance clonally replicated planting stock to forest plantations and may also be a valuable tool for the development of efficient gene transfer techniques. Although high rates of plant propagation from axillary shoot proliferation can be achieved easily in many Eucalyptus species, even higher multiplication rates through SE have been recorded in other tree species. If the clonal propagation of Eucalyptus through SE proves to be an effective propagation method, it has the potential to meet the increasing industrial demands for high-quality uniform materials and to rapidly capture the benefits of breeding programs. Since 2002 a reproducible protocol for SE induction from mature zygotic embryos of E. globulus has been available. However, for SE to be useful in E. globulus improvement programs, the frequency of SE initiation, maturation, germination and acclimatisation needs to be improved and controlled. If this technology could be extended to elite germplasm, it would become an economically feasible tool for large-scale production and delivery of improved planting stock. This is one of the greatest current challenges in Eucalyptus tissue culture. In this review we update the most important aspects of SE in Eucalyptus with particular emphasis on E. globulus. We highlight both genetic control and the influence of different environmental factors in the SE process (e.g. medium composition, antioxidants, light and plant growth regulators), from induction to plant acclimatisation in both primary and secondary SE.

Acacia mangium Willd. - A Fast Growing Tree for Tropical Plantation

Acacia mangium is an evergreen fast-growing tropical tree, which can grow up to 30 m tall and 50 cm thick, under favorable conditions. It is a low-elevation species associated with rain forest margins and disturbed, well-drained acid soils. It is native to Papua, Western Irian Jaya and the Maluku islands in Indonesia, Papua New Guinea and north-eastern Queensland in Australia. Due to its rapid growth and tolerance of very poor soils, A. mangium was introduced into some Asian, African and western hemisphere countries where it is used as a plantation tree. A. mangium has good quality wood traits, such as a comparatively low proportion of parenchymatous cells and vessels, white and hard wood, and high calorific value. Therefore, it is useful for a variety of purposes, such as furniture, cabinets, turnery, floors, particleboard, plywood, veneer, fence posts, firewood, and charcoal. It is also being used in pulp and paper making because it has good pulp traits, with high yields of pulp, quality of kraft, and produces paper with good optical, physical and surface properties. Because there are significant provenance differences in growth rate, stem straightness, heartwood formation and frequency of multiple leaders, the productivity and quality also varies depending upon environmental conditions, so genetic improvement programmes have been undertaken in countries like Australia, India, Indonesia, Malaysia, the Philippines, Taiwan and Thailand. The programme includes provenance identifications and testing, plus tree selection and clonal multiplication, establishment of seed orchards and hybridization. The phenology, reproductive biology, fruit characteristics, silvicultural practices for cultivation, pest and diseases problems, production of improved planting stock, harvesting, wood properties and utilization have been discussed in this paper.

Silvicultural management of white pines in western North America

SummarySince the introduction prior to 1915 of white pine blister rust (Cronartium ribicola) into the forests of western North America, many populations of native white pine species have seriously declined. Because western white pine (Pinus monticola) and sugar pine (P. lambertiana) are highly valued timber species, their silviculture under intensive management is well‐documented. The silviculture of other white pine species has received less attention but is no less important. For all western species, silvicultural management is a key component for sustaining and restoring viable white pine populations. This review examines approaches for assessing and reducing blister rust hazard, regenerating white pine stands, and tending established stands to reduce damage and impact from blister rust. Hazard and risk ratings provide means for assessing the potential severity of blister rust infestation and its probable impacts on management. An epidemiological simulation model is available for describing complex pathosystem interactions, their consequences on white pine growth and survival, and likely outcomes of silvicultural activities. Until the 1960s, Ribes eradication was the principal method for blister rust control; it is now rarely used except for high‐value trees. The choices of harvest and site preparation methods are critical for successful white pine regeneration. As host responses to blister rust infection are inherited, regeneration is an opportunity to increase seedling survival and disease resistance. For artificial regeneration, the western genetics programmes provide improved planting stock. For natural regeneration, the selection and retention of well‐adapted white pines as seed sources can enhance stand genetics. Thinning and pruning are common silvicultural activities for tending stands and are readily modified for blister rust‐infested stands. Although biological and chemical agents have been used, their performance has been less than satisfactory. Likewise, genetics and other silvicultural practices have also demonstrated limited success in blister rust control. An alternative, adaptive approach could use both silvicultural and genetic techniques to mitigate impacts and maintain white pines.

Developing African mahogany (Khaya senegalensis) germplasm and its management for a sustainable forest plantation industry in northern Australia: progress and needs

SummaryThe demonstrated wide adaptability, substantial yield potential and proven timber quality of African mahogany (Khaya senegalensis) from plantings of the late 1960s and early 1970s in northern Australia have led to a resurgence of interest in this high-value species. New plantations or trials have been established in several regions since the early 1990s—in four regions in north Queensland, two in the Northern Territory and one in Western Australia. Overall, more than 1500 ha had been planted by early 2007, and the national annual planting from 2007–2008 as currently planned will exceed 2400 ha. Proceedings of two workshops have summarised information available on the species in northern Australia, and suggested research and development (R&D) needs and directions.After an unsustained first phase of domestication of K. senegalensis in the late 1960s to the early 1970s, a second phase began in northern Australia in 2001 focused on conservation and tree improvement that is expected to provide improved planting stock by 2010. Work on other aspects of domestication is also described in this paper: the current estate and plans for extension; site suitability, soils and nutrition; silviculture and management; productivity; pests and diseases; and log and wood properties of a sample of superior trees from two mature plantations of unselected material near Darwin. Some constraints on sustainable plantation development in all these fields are identified and R&D needs proposed. A sustained R&D effort will require a strategic coordinated approach, cooperative implementation and extra funding. Large gains in plantation profitability can be expected to flow from such inputs.

Forest biotechnology: Innovative methods, emerging opportunities

The productivity of plantation forests is essential to meet the future world demand for wood and wood products in a sustainable fashion and in a manner that preserves natural stands and biodiversity. Plantation forestry has enormously benefited from development and implementation of improved silvicultural and forest management practices during the past century. A second wave of improvements has been brought about by the introduction of new germplasm developed through genetics and breeding efforts for both hardwood and conifer tree species. Coupled with the genetic gains achieved through tree breeding, the emergence of new biotechnological approaches that span the fields of plant developmental biology, genetic transformation, and discovery of genes associated with complex multigenic traits have added a new dimension to forest tree improvement programs. Significant progress has been made during the past five years in the area of plant regeneration via organogenesis and somatic embryogenesis (SE) for economically important tree species. These advances have not only helped the development of efficient gene transfer techniques, but also have opened up avenues for deployment of new high-performance clonally replicated planting stocks in forest plantations. One of the greatest challenges today is the ability to extend this technology to the most elite germplasm, such that it becomes an economically feasible means for large-scale production and delivery of improved planting stock. Another challenge will be the ability of the forestry research community to capitalize rapidly on current and future genomics-based elucidation of the underlying mechanisms for important but complex phenotypes. Advancements in gene cloning and genomics technology in forest trees have enabled the discovery and introduction of value-added traits for wood quality and resistance to biotic and abiotic stresses into improved genotypes. With these technical advancements, it will be necessary for reliable regulatory infrastructures and processes to be in place worldwide for testing and release of trees improved through biotechnology. Commercialization of planting stocks, as new varieties generated through clonal propagation and advanced breeding programs or as transgenic trees with high-value traits, is expected in the near future, and these trees will enhance the quality and productivity of our plantation forests.

A review of the relative roles of silviculture and tree breeding in tree improvement: the example of Sitka spruce in Britain and possible lessons for hardwood breeding

Summary Research involving the silviculture and genetic improvement of Sitka spruce ( Picea sitchensis (Bong.) Carr.) is the most advanced of any tree species in Great Britain. Best practice advice and improved planting stock material are now available as growers attempt to maximize their returns according to their objectives. This paper reviews the various advances made in silvicultural and tree breeding research and summarizes the main lessons that have been learnt and the time scales involved. From this analysis it is possible to gain a clearer picture of the limits that silviculture and genetic improvement have for further tree improvements. The need for a combined approach in order to maximize the benefi ts of good silviculture and genetically improved material is emphasized. Recommendations have then been proposed for hardwood tree improvement in the light of the experience with Sitka spruce. In particular, there is the need for silviculture and tree breeding to address improvement of timber quality rather than purely vigour, and the use of parallel breeding strategies to enable improved material to come onto the market as quickly as possible. The need to make greater use of registered seed stands and untested clonal seed orchards, based on plus trees, as well as a more thorough system of progeny testing and selection is also discussed.

Effect of growth rate on wood properties of genetically improved Sitka spruce

Summary This study examined the wood properties of 24-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.) progenies with highly contrasting growth rates. The progenies were established as part of a breeding programme to improve growth rate and stem form. Trees from three progenies were selected with a high growth rate relative to an unimproved control of directly imported material from the Queen Charlotte Islands (QCI), British Columbia, Canada. Trees from a further three progenies were selected that displayed a similar growth rate to the QCI control. At the time of sampling, the fastgrowing progenies had a mean volume gain over the QCI and slow-growing progenies of ~70 per cent. Trees from the fast-growing progenies were found to have significantly larger branches, less latewood, and more compression wood in comparison with the QCI control and the slow-growing progenies. On the other hand, trees from the fast-growing progenies had a smaller grain angle than the QCI control. While fast-growing progenies had lower wood density than the control, this was not significantly different. These findings suggest that, in general, the criteria used to select Sitka spruce trees in the forest as potential candidates for the breeding population would indeed lead to significant improvements of the growth performance and grain angle from improved planting stock. Breeders need to be aware, however, of possible negative influences of such selection criteria on other stem and wood properties known to influence wood strength.

Performance of Improved Pinus sylvestris in Northern Sweden

Genetic gain from utilization of improved planting stock of Scots pine (Pinus sylvestris L.) in northern Sweden is presented. A total of 36 genetic field tests, comprising more than 177 000 individual trees, was analysed with respect to tree height and survival at the age of 9–13 yrs. The field tests included control pollinated progenies from 434 phenotypically selected parent trees constituting the clones of 11 commercial seed orchards, and 16 natural stand control lots. The field test covered a wide geographical and climatic gradient (latitude 62.3–67.8° N, temperature sum 496–1056 day-degrees). covering the area used for commercial forestry in northern Sweden. Progenies of selected trees had 10% superior height growth, whereas differences in survival were small and non-significant. Thus, selection of individual trees within a stand did not result in the strong negative relationship between growth and survival normally observed among provenances of different latitudinal origin. The height superiority did not show any significant dependency on the growth conditions of the site (temperature climate), the transfer distance of the seedlings or the age of trees. The effect of improved regeneration stock on volume production during an entire rotation period was discussed using growth and yield functions, and indicated substantial volume gain at the time of both first thinning and final harvest.

Performance of Improved Pinus sylvestris in Northern Sweden

Genetic gain from utilization of improved planting stock of Scots pine ( Pinus sylvestris L.) in northern Sweden is presented. A total of 36 genetic field tests, comprising more than 177 t 000 individual trees, was analysed with respect to tree height and survival at the age of 9-13 yrs. The field tests included control pollinated progenies from 434 phenotypically selected parent trees constituting the clones of 11 commercial seed orchards, and 16 natural stand control lots. The field test covered a wide geographical and climatic gradient (latitude 62.3-67.8° N, temperature sum 496-1056 day-degrees), covering the area used for commercial forestry in northern Sweden. Progenies of selected trees had 10% superior height growth, whereas differences in survival were small and non-significant. Thus, selection of individual trees within a stand did not result in the strong negative relationship between growth and survival normally observed among provenances of different latitudinal origin. The height superiority...

Results from Genetic Tests of Selected Parents of Douglas-Fir (Pseudotsuga menziesii [Mirb.] Franco) in an Applied Tree Improvement Program

Abstract Results from genetic tests, and genotype by environment interaction studies in six low-elevation breeding zones of Weyerhaeuser Company's Western Washington and Oregon Douglas-fir tree improvement program are summarized. Phenotypic selection in natural stands resulted in a 5% improvement in juvenile height over nonselect seed lots. Comparisons with nonselect sources, of offspring from parents in the top 50% performers in tests, indicated a 10% increase for the same trait. Seed produced in a 50% rogued seed orchard is thus expected to provide improved planting stock with a gain of 10% in juvenile height growth. Several select parents are producing offspring that are consistently performing in excess of 10% over nonselects. Estimates of breeding zone, breeding zone by location, and family by location interaction effects are small relative to family and planting location effects. Tests of families established on environmentally diverse sites indicate a striking lack of large family by planting location interaction. In tests showing statistically significant interactions, such interactions are caused by a relatively small number of families. We did observe earlier budbreak and a higher spring frost susceptibility of Oregon sources established on Washington sites. We conclude that allocation and utilization of select families within Weyerhaeuser's Oregon and Washington ownership should not be constrained by the currently defined breeding zone boundaries, but based on parental performance and stability for growth and adaptive traits in general. We further suggest that the necessity for maintaining separate breeding zones, within Washington and Oregon, in subsequent cycles of recurrent selection is questionable. Average individual tree heritability, from 65 6-parent disconnected diallels, is 0.13 for age 6 and age 8 height. Dominance genetic variance is estimated to be one-half that of additive genetic variance for the same traits.The environmental designs and test establishment methods used resulted in acceptable levels of statistical precision for juvenile growth traits. Individual test least significant range values (LSR) resulted in significant family mean percent height differences of 8 to 26, and averaged 13% for diallels, and full-sib and half-sib tests. For. Sci. Monogr. 32:1-35.