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The study investigates the long-term impact of Lophodermium needle cast on open-pollinated Scots pine progenies in Latvia. A significant impact of cumulative needle cast damage on growth and survival was found. Notably, 51% of trees experienced severe damage after the 4th growing season. Genetic factors played a role in survival at 12 years. Height growth was significantly affected, with height at age 3 and cumulative needle cast damage as key predictors for heights at ages 12 and 16. Genetics demonstrated a substantial impact, with heritability coefficients of 0.25 for cumulative needle cast damage and 0.24 for height, and negative genotypic correlations (rG ≥ -0.71) between the traits. Selecting the top 10% families based on height at 12 years yielded a 14.2% improvement in height and a simultaneous 8.4% reduction in cumulative needle cast damage, enhancing survival by 9.8%. Thinning somewhat mitigated the negative effect of needle cast. The findings highlight the need for adaptive forestry strategies in the Baltic Sea region. [ABSTRACT FROM AUTHOR]

In the Andean-Patagonian region of Argentina, Pinus ponderosa Douglas ex C. Lawson is the most widely cultivated forest tree species. Its breeding program, started in 1998, is now progressing towards the establishment of 1.5 generation clonal seed orchards. Considering recent advances in the phylogeny and taxonomy of the species, it is necessary to delve deeper into the genetic variation of the breeding population. Here, we first aim to address a previously unresolved question concerning the putative genetic lineages (varieties) of P. ponderosa that were introduced from the USA. We assessed this question through the molecular characterization of the nad1 second intron minisatellite of the mitochondrial genome of 61 plus trees planted in 1.0 clonal seed orchards, followed by Sanger sequencing to determine mtDNA haplotypes. Then, we conducted a nursery common garden trial to determine the relative contribution of the genetic factors (lineages and clones) to the variation in early growth traits, which may reflect adaptation across native geographic ranges and are also important for nursery stock production. We found three mtDNA variants, which correspond to haplotypes H1, H5 and H8, form the North-West native range of the species. In general, the variation in early seedling growth traits was not attributable to the haplotypic groups; instead, variation among clones was high and heritable. Considering the initial performance of the breeding population, it appears feasible to manage 1.0 and 1.5 clonal seed orchards by maintaining sub-specific taxa mixed together, while assessing the potential impact of intra-specific hybridization and field performance of progeny for timber production and resilience to climate change. [ABSTRACT FROM AUTHOR]

The expansion of forest plantations to supply the wood market requires selection of genotypes that can provide high gains, which may compromise long-term tree breeding programs. With the final purpose of producing quality sawn wood, the aims of this study were to: (a) estimate genetic parameters for a progeny/provenance test of Plathymenia foliolosa Benth; (b) carry out optimized selection based on an inbreeding rate (F) from 0 to 7% in progeny/provenance tests evaluated at 35 months for P. foliolosa and Cordia trichotoma (Vell.) Arrab. ex Steud, and at 42 months for Zeyheria tuberculosa (Vell.) Bureau ex Verl.; (c) develop a practical index for balancing gains and F; d) and indicate the most appropriate genetic base structure based on effective population size ( N e ) to subsidize conservation strategies, breeding programs, and clonal orchard with those species native from Brazil. Diameters at breast height (DBH) were obtained in progeny/provenance tests conducted in the south of Bahia–Brazil. For P. foliolosa, the moderated heritability (h2a) value of 0.55 demonstrated favorable conditions for selection based on DBH. For this trait, there is better possibility of achieving progressive gains by exploiting genetic variability into the families (CVgi). Simulation of scenarios without optimization for P. foliolosa, C. trichotoma and Z. tuberculosa showed a high possibility of gains for breeding programs, ranging between 95.6 and 311.05%. However, in those scenarios, high rates of F were also observed. For the three species, selection based on the selection optimization index (SOI) was proposed in order to balance ideal increments in genetic gains and maintenance of genetic diversity. With the use of SOI, it was possible to simulate selection of scenarios with good prospects of gain balanced with N e in a practical and direct manner for germplasm conservation strategies, production of improved seeds in clonal orchards, and tracking recombination cycles within breeding populations. [ABSTRACT FROM AUTHOR]

Trees in breeding programmes are often selected at 1/4–1/3 of rotation, called 'early selection', which is typically between 8 and 10 years in radiata pine. However, differences between populations and genotypes selected for either basic density or wood stiffness are already apparent at age 2. We report the application of very early screening techniques for wood properties in the New Zealand Radiata Pine Breeding Programme deployment populations. Approximately 3000 trees representing three populations with 92 families and 10 clones were grown in a common garden trial, leaning for 21 months to separate compression and opposite wood. The trees were harvested and analysis carried out separately by wood type. The trial showed the existence of large variability in wood properties at early age, in some cases similar to variability near rotation age, and moderate to high degree of genetic control ( 0.35 ≤ h 2 ≤ 0.71 ). The genetic association between traits was strong, particularly between wood stiffness and longitudinal shrinkage ( - 0.69 ) and between longitudinal and volumetric shrinkage (0.83), suggesting that improving stiffness would also have a strong effect on improving dimensional stability. Basic density was also associated with stiffness and shrinkage, but with lower predictive capacity. These results can be used for roguing deployment populations-which already contain superior growing trees-and quickly upgrade the wood quality of seeds and clones currently available to New Zealand forest growers. We discuss necessary modifications to turn this research work into operation to screen any new material before commercial release. [ABSTRACT FROM AUTHOR]

Productive Scots pine (Pinus sylvestris L.) stands in the Baltic region ensure high-quality sawlogs for the timber market and contribute to carbon sequestration. Spike knots are serious stem defects, which reduce the proportion of valuable timber; therefore, the extent of genetic control of their occurrence and relationship with other traits must be assessed for the potential to reduce negative impact via tree breeding. We aimed to evaluate the family effect on the presence of spike knots and its relation to growth traits in open-pollinated Scots pine progenies. A higher incidence of spike knots was associated with better height growth and the presence of lammas shoots. The family had a statistically significant effect on growth and spike knots, yet a mainly weak genotypic correlation was observed between both traits (rG = − 0.25 ... 0.40). The family mean heritability of the spike knots was moderate (hf2 = 0.42 ... 0.46), opposite to very low (h2 = 0.02... 0.05) single tree heritability. Although the presence of lammas shoots was low and was not affected by genetics, it showed a strong positive genotypic relationship with the formation of spike knots in the next growing season (rG = 0.80). The potential to select fast growing families with a low probability of spike knots was indicated, but a more comprehensive analysis is necessary to determine the extent of the genetic relationship between this stem defect and lammas shoots. [ABSTRACT FROM AUTHOR]

An immediate concern of commercial tree plantation is the depleting water resource and drastic change in climatic conditions, which adversely affect the biomass productivity. Maximizing productivity from the available water and nutrient resources is presently the focus of most tree breeding and plantation programs. In Eucalyptus species variations in response to water deprived conditions are reported between species, among provenances and between clones. In the present study, 126 clones derived from the breeding program of Eucalyptus camaldulensis James. and Eucalyptus tereticornis sm. were screened for their response to progressive dehydration stress under controlled environmental conditions and morpho-physiological changes were recorded. Specific Leaf Area (SLA) and Relative Water Content (RWC) were found to be effective dehydration stress indices in both the species. Drought Susceptibility Index (DSI) which measures the decrease in yield of a genotype under drought conditions with respect to mean reduction of all genotypes studied, is a major selection criteria and quantitative indicator in selecting varieties for dehydration tolerance. DSI was recorded for each measured traits and SLA–DSI and RWC–DSI clustered the clones based on their tolerance/ susceptibility to dehydration stress. Additionally, ten prospective clones were selected as dehydration tolerant genotypes and are probable candidates for future multi-environment evaluation under arid and semi-arid conditions for deployment in plantation and breeding programs. [ABSTRACT FROM AUTHOR]

Forest plantations play an important role in maintaining a supply of high-quality timber from managed forest. With an expected increase in the prevalence of drought in some forested areas, climate change increases concerns about future seedling growth. A promising approach to promote the suitability of plantation seedlings to current and future climate would be to use variation in growth and wood traits of trees under drought as selection criteria in tree breeding programs, especially at a young stage when they are most vulnerable to drought. We evaluated the genetic control of the growth and wood density response of white spruce clonal seedlings submitted to various drought conditions in a greenhouse experiment. By varying the watering treatment of 600 two year-old seedlings from 25 clones, we simulated three levels of drought-induced stress during two growing seasons. Apical and radial growth decreased markedly as the intensity of drought increased, whereas wood density tended to increase. We also developed a woody biomass index composed of wood density and ring area, which was observed to decrease slightly with increasing drought. There was important variation in all traits among clones and heritability tended to decrease with the intensity and duration of drought-induced stress, mainly for wood density and radial growth. However, the heritability of apical growth tended to increase under drought conditions. Our results show that the response of young white spruce clones to drought is highly variable, and together with the significant levels of heritability noted, the results indicate that multi-trait genetic selection for drought stress response at a young age could represent a promising approach to increase resilience to drought. [ABSTRACT FROM AUTHOR]

The fields of tree breeding and genetic engineering can be perceived as being antagonistic towards each other—genetic engineers suggesting that tree breeding is too slow and expensive and tree breeders suggesting that genetic engineering is not practical and too expensive. We argue here that both fields have much to offer forestry and the success of each is intimately tied to the other. The major purposes of genetic engineering in forestry are described as well as the importance of evaluating tree engineering initiatives in the context of tree improvement and silviculture and integrating genetic engineering with tree breeding from start to finish. A generalized approach is developed that meets these requirements and demonstrates the interrelationships between the activities and phases of each program. In addition, a case study of the American chestnut (Castanea dentata) is provided to underscore the value of integrating genetic engineering and tree breeding programs to achieve a long-term conservation goal. [ABSTRACT FROM AUTHOR]

Introduced pests (insects and pathogens) have rapidly increased the numbers of at-risk native forest tree species worldwide. Some keystone species have been functionally extirpated, resulting in severe commercial and ecological losses. When efforts to exclude or mitigate pests have failed, researchers have sometimes applied biotechnology tools to incorporate pest resistance in at-risk species to enable their reintroduction. Often erroneously equated solely with genetic engineering, biotechnology also includes traditional and genome informed breeding—and may provide a holistic approach toward applying genomic-based information and interventions to increase tree species' pest resistance. Traditional tree breeding is responsible for successes to date, but new technologies offer hope to increase the efficiency of such efforts. Remarkable recent progress has been made, and for some at-risk species, novel biotechnological advances put reintroduction within reach. The high costs of reintroduction of at-risk species at necessary scale, however, will initially limit the pursuit to a few species. Successful deployment of pest resistant material may require improved species-specific knowledge and should integrate into and leverage existing reforestation systems, but these operations are sometimes rare where pest threats are greatest. While use of some biotechnologies, such as traditional tree breeding, are commonplace, others such as genetic engineering are controversial and highly regulated, yet may be the only viable means of achieving reintroduction of some at-risk species. Efforts to modify policy toward allowing the use of appropriate biotechnology, especially genetic engineering, have lagged. Provided that risk-benefits are favorable, policy is likely to follow with public opinion; in some countries, society is now increasingly open to using available biotechnologies. Continued engagement using the most recent advances in social science to build public trust, combined with a science-based collaboration among land managers and regulators, will generate the collective momentum needed to motivate policymakers to act rapidly given the speed at which forest health threats unfold and the large areas they affect. [ABSTRACT FROM AUTHOR]

Scots pine (Pinus sylvestris L.) seeds have variable levels of primary dormancy which reflect within-species adaptation to local environments. The objective of this study was to use a thermal time approach to determine whether primary dormancy levels in seeds were correlated with mean ambient temperature during temperature-sensitive phases of the reproductive cycle. Seedlots were obtained from a single open-pollinated clonal seed orchard in five crop years and germinated over a wide temperature range (7–35 °C) to calculate base temperature for germination with and without pre-chills (4 and 8 weeks). Primary dormancy levels varied amongst seedlots collected in different crop years (CY). Unchilled seeds were the most dormant for CY2007 (Tb = 10.9 °C) and least dormant for CY2012 (Tb = 5.6 °C). Base temperatures for germination were correlated with mean ambient temperature during different phases of the reproductive cycle. There was a strong positive correlation between base temperature for germination of unchilled seeds and mean temperature during pollination and early pollen tube growth. This suggests that maternal environmental effects during this phase could potentially select for dormant or non-dormant seeds, which has implications for tree breeding and seedling production in forest nurseries. [ABSTRACT FROM AUTHOR]

The study of vegetative phenology is important to understand adaptation to different environments and potential trade-offs with growth traits. Crown leaf-out and leaf-fall phenology was evaluated on 168 open-pollinated families from 19 Cedrela odorata provenances in an eleven-year-old provenance/progeny trial established in the state of Veracruz, Eastern coast of Mexico. The objectives were: (a) to evaluate the extent of inter- and intra-population genetic variation of leaf phenology traits; (b) to examine the relationship between leaf phenology traits and climate variables at the population level; (c) to estimate the genetic relationships between leaf phenology and growth traits; and (d) to evaluate the accuracy, in terms of genetic control, of using alternative methods to measure leaf phenology in broadleaf trees. The study revealed significant genetic variation in leaf phenology traits both among and within populations. Leaf-out traits showed higher genetic variation than leaf-fall traits. A moderate to large genetic differentiation among Cedrela odorata populations was found; Qst values for leaf-out were 2–6 times higher than those for leaf-fall. Leaf-fall was primarily associated with mean annual temperature, while leaf-out and length of the leafless period were related to annual precipitation and the aridity index of the site of origin. Leaf phenology traits showed moderate to high genetic control (h2i = 0.12–0.67; h2f = 0.27–0.72). However, it was higher for leaf-out traits, so they might play a more important adaptive role. Genetic correlations between leaf phenology and growth traits allow selecting early flushing genotypes within populations to increase adaptation and growth, but caution should be taken when selecting among populations. [ABSTRACT FROM AUTHOR]

Spanish red cedar, Cedrela odorata L. (Meliaceae), is a valuable timber tree in tropical American forests. Existing demand for elite individuals endangers the conservation of interesting germplasm, prompting the development of efficient protocols for the establishment of orchards for tree breeding. Based on previous work regarding grafting adult individuals onto young rootstocks, superior trees from Calakmul Biosphere Reserve in Campeche, Mexico were employed as a source of explants for plant regeneration after successive rounds of grafting and micrografting onto juvenile rootstocks. The results showed that root length and appearance, internode distance, leaf length and number, and plant height values for trees derived from successive rounds of grafting and micrografting were similar to those obtained from juvenile trees derived from seeds, suggesting that developmental traits associated with reinvigoration were partially induced following the reported procedure. This protocol may be useful for the propagation of mature elite trees belonging to the Meliaceae family. [ABSTRACT FROM AUTHOR]

Non-spatial and spatial analyses were carried out to estimate genetic parameters for growth and stem straightness traits between ages 4 and 7 in two series of eight progeny trials of Pinus elliottii Engelm. var. elliottii (PEE) established in 2004 and 2008, comprising 429 open-pollinated families from Instituto Nacional de Tecnología Agropecuaria (INTA) tree breeding population in Argentina. A first-order autoregressive spatial mixed model was found to significantly improve the fit of the model, compared with the standard non-spatial mixed model approach, due to substantial spatial heterogeneity within sites. The average individual-tree narrow-sense heritability estimates based on this spatial analysis were 0.49 for diameter at breast height, 0.36 for total height, and 0.48 for volume, with stem straightness being low to moderate (average = 0.11). The additive genetic correlation estimates between growth traits were positive (0.51 ≤ r ^ a ≤ 0.99) and statistically significant from zero. In contrast, the genetic correlations between growth traits and stem straightness although in general also positive were not significantly different from zero (− 0.22 ≤ r ^ a ≤ 0.59). Age-to-age genetic correlations were consistently higher for growth traits ( r ^ a ≥ 0.81) than for stem straightness ( r ^ a ≥ 0.33). The average additive genetic correlation estimated between sites within test series was high for all traits evaluated (average > 0.72). In contrast, average additive genetic correlation estimated between sites across series was slightly lower (average < 0.63). Implications of all these parameter estimates for genetic improvement of PEE in Argentina are discussed. [ABSTRACT FROM AUTHOR]

Financial performance of the P. patula × P. tecunumanii, P. greggii × P. tecunumanii, P. taeda × P. tecunumanii hybrids and their parental species was studied for South Africa. A model was developed for use in determining the profitability of a tree-breeding program (TBP) with pine hybrids in commercial plantations. Growth measurement data were collected in four, 12-year-old genetic trials on Mondi and Sappi land holdings in South Africa. Growth models developed for P. patula and P. taeda in South Africa were used to infer models for the other taxa and to calculate the optimal financial rotation age at discount rates of 6 and 8%. Financial data on pine plantations were collected from different sources in South Africa. Optimal rotation lengths in this study were found to be between 12 and 16 years for pulpwood and 17 years for sawtimber. The model output shows the net present value (NPV), the internal rate of return, and the minimum area that a tree grower has to plant every year in order to justify the investment in a TBP. A stochastic approach with Monte Carlo simulation showed that the sensitivity of NPV to uncertainty in the wood price was greater than that for the planting, harvesting, and transport costs. [ABSTRACT FROM AUTHOR]

Understanding the variation of mating patterns in disturbed habitats provide insight into the evolutionary potential of plant species and how they persist over time. However, this phenomenon is poorly understood in tropical dryland tree species. In the present study, we investigated how Acacia senegal reproduces in two different environmental contexts in Kenya. Open-pollinated progeny arrays of 10 maternal trees from each environmental context were genotyped using 12 nuclear microsatellite markers. Overall, A. senegal displayed a predominantly allogamous mating pattern. However, higher multilocus outcrossing rate ( tm) was found in Lake Bogoria ( tm = 1.00) than in Kampi ya Moto population ( tm = 0.949). Higher biparental inbreeding ( t − t = 0.116) and correlation of outcrossed paternity ( rp = 0.329) was found in Kampi ya Moto than in Lake Bogoria population ( t − t = 0.074, rp = 0.055), showing the occurrence of mating among relatives. Coefficient of coancestry (Θ = 0.208) showed that full-sibs constitute about 21% of the offspring in Kampi ya Moto population compared to about 14% (Θ = 0.136) in Lake Bogoria population. The results demonstrate that low adult tree density of A. senegal may be promoting seed production through consanguineous mating and suggest that man-made disturbance can affect mating patterns of the species. Despite these mating differences, trees from both populations can contribute as seed source for conservational plans, and to support effective genetic conservation and artificial regeneration programs of A. senegal. We suggest collection of seeds from at least 42 and 63 trees in Lake Bogoria and Kampi ya Moto populations, respectively, to retain a progeny array with a total effective population size of 150. [ABSTRACT FROM AUTHOR]

Genetic trials at three dryland sites in southern India compared 183 families from 4 superior natural provenances, 48 families from locally developed seed sources and 10 commercial clones of Eucalyptus camaldulensis. Three of the local seed sources were seed production areas developed by phenotypic selection for growth from an initial broad base of superior natural provenances, and two were clonal trials. The local seed sources grew significantly faster to 3 years than the natural provenances and the clones. Mean survival at 3 years of the natural provenances (72 %, across the three sites) was better than that of local seed sources (67 %) and clones (50 %). The three types of planting materials did not differ significantly in their wood basic density or NIR-predicted lignin content, while clones had significantly higher NIR-predicted pulp yield. Site mean wood density was highest (579 kg m), and pulp yield lowest (43.7 %) at the driest site where growth was slowest, while at the wettest, most productive site, density was 517 kg m and pulp yield 46.5 %. Narrow-sense heritabilities and inter-site genetic correlations for growth and wood traits were moderate to high. Genetic correlations between growth and wood traits did not differ significantly from zero. Unpedigreed seed production areas developed from an appropriate genetic base of best provenances, may provide a simple option to mass-produce improved seed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We evaluated eight-year-old seedlings in a black walnut ( Juglans nigra L.) progeny test for two quantitative and two qualitative traits. We also used 12 microsatellite markers to genotype the 328 progeny and their maternal parents. Seedling family growth and quality was evaluated based on the progeny test map. These values were compared to family growth and quality after seedlings were genotyped and reassigned to families by parentage assignment software. After genotyping and parentage analysis, about 80 % of the offspring were assigned to the same half-sib family indicated on the planting map. Considerable differences were observed between the ranks of half-sib families based on the planting-map versus the ranks of the families based on the exclusion/assignment of progeny to their family based on genotypes. Analysis of the data without genotypic assignment of progeny to their correct family revealed that the family effect for height was significant, as was family effect for diameter. After seedlings were reassigned to half-sib families based on genotypic information, neither the family effect for height nor the family effect for diameter was significant. The efficiency of the mixed model ANOVA, as measured by Akaike Information Criterion improved by about 30 % after genotyping and exclusion/reassignment of progeny. These results show that genotyping progeny can have a significant effect on the rank of families and potential selection of individuals from a progeny trial, the quality of data analysis, and the efficiency and efficacy of breeding operations. [ABSTRACT FROM AUTHOR]

Gmelina arborea is a valuable plantation tree species that is native to South and Southeast Asia. In this study, 534 samples representing 19 natural populations in India, China, Thailand and Myanmar were analyzed with 10 polymorphic microsatellite markers. The genetic diversity analysis revealed highly polymorphic loci (N = 16.4), a good level of genetic diversity (H = 0.56; H = 0.83) and the deficiency of heterozygotes in G. arborea populations evidenced by positive fixation index and deviation from Hardy-Weinberg Equilibrium in all loci and most populations. The Analysis of Molecular Variance attributed 21, 10 and 69% of total genetic diversity to among-region, among-population (within region) and within-population variation. Unweighted Pair Group Method with Arithmetic Mean dendrogram and Principle Coordinate Analysis revealed three separate clusters composed of China, India and Thailand/Myanmar that were consistent with geographical distance and the presence of natural barriers to gene flow. Populations from within India grouped together genetically consistent with geographical locations, with the exception of the Nowgong population (eastern India), that might have originated from the Kasa area (western India) with which it has high genetic similarity. Understanding genetic diversity and structure of G. arborea populations serve as an important reference for tree breeding programs and conservation strategy. Breeding populations of G. arborea should include selections from each of the major geographic regions to maximize genetic diversity and heterosis. Vegetative propagated clones of elite trees can be used for plantation to address the issue of high level of segregation among seed derived plants. [ABSTRACT FROM AUTHOR]

The Baobab tree ( Adansonia digitata L.) is a key multipurpose species for the African region. In the recent years there has been an extended commercial interest for different A. digitata products. As a spectacular African key species there has been a growing interest from NGO′s and various research groups. A research group, focussing on the following countries Burkina Faso, Mali and Niger, has participated in a concerted research action with cross counter disciplinary cooperation between plant physiology, population genetics, tree breeding, food science, and socioeconomics. This paper presents a review and the way knowledge gaps are being addressed using the above mentioned approach. The overall work was initiated in 2005-2006 when a large collection of A. digitata seeds was carried out in 15 African countries. Fourteen populations were selected in Burkina Faso, Mali, and Niger including more than 400 superior trees, and many of the trees have been selected along with farmers in a participatory process. Studies have been initiated in all countries on geographic variation of growth, adaptive and phenological traits. This includes studies in the nursery, establishment of international provenance series, seed orchards and studies of gene flow and phylogeographic variation with various markers. Specific nursery trials have been established in order to study provenance and progeny performance related to drought stress. Several stress related characteristics are being measured. Preliminary observations showed large morphological variation between African provenances of A. digitata. Food properties of plant parts have been studied within and between populations. This includes studies of total biomass production, vitamin A, B1, B2, and various minerals. The influence of stress will be related to these parameters. Fruits, which are rich in sugar and vitamin C, are used as an ingredient in juice and other foods. Seeds can be used directly as food ingredient or in fermented condition (Maari). The fermentation process was previously poorly described. Therefore, the microorganisms associated with Baobab seeds fermentation have been identified and a starter cultures for control production has been proposed. The efficiency of dissemination of superior A. digitata trees depends on vegetative propagation. Various grafting methods are currently being tested in cooperation with farmers. Micropropagation is tested as well as a method for clone propagation. The accumulated knowledge will be applied for a domestication strategy of A. digitata in Burkina Faso, Mali and Niger. The outcome from this study will be guidelines for protection and management of the germplasm of A. digitata resources. [ABSTRACT FROM AUTHOR]

Accurate prediction of whole-tree wood basic density (BD) from indirect density measures is important for estimating Eucalytpus globulus breeding values and genetic gain. We measured 100 E. globulus trees at 6.5 years of age on each of a high productivity site (Albany) and a low productivity site (Esperance), sampling 16 full-sib families and seven open-pollinated ‘check’ seedlots. On each tree we assessed pilodyn penetration at 1.3 m and BD of: (a) the outer 10 mm which was penetrated by the pilodyn pin of a bark-bark core, (b) a whole bark-bark core at 1.3 m, (c) a cross-sectional disk at 1.3 m and (d) the whole tree, represented by cross-sectional disks at five heights. Site effects and genetic values for families and checks were determined by mixed model analysis. A trend of increasing BD from pith to bark was more pronounced at Albany, where wood formed before age 3.5 years was 12 kg/m3 less dense than at Esperance ( P = 0.01) and wood formed from 3.5 to 6.5 years was 27 kg/m3 denser than at Esperance ( P < 0.001). Mean whole-tree BD was 19 kg/m3 greater at Albany ( P < 0.001). Pilodyn penetration was well-correlated with BD of the 10 mm sample of penetrated wood and this relationship was not greatly affected by site variation. Genetic values for pilodyn penetration formed precise relationships with BD of breast-height discs and whole-tree BD although they were site-specific. Pilodyn penetration was a better predictor for genetic values of whole-tree BD than were bark-bark cores. [ABSTRACT FROM AUTHOR]

Acacia mangium is a major plantation species for the pulp and paper industry in south-east Asia and there are a number of active breeding programs. The species is predominantly outcrossing, but with a demonstrated capacity to set selfed seed where outcross pollen is limited, with consequent inbreeding depression in the progeny. Current controlled pollination methods therefore include a time-consuming emasculation step. We used microsatellite genotyping of seedlings to determine the consequences of outcross pollination with and without emasculation. Only 1 of 3 mother trees set a small amount (5%) of selfed seed. Using whole inflorescences from the male parent as the pollen applicator rather than sieved pollen reduced outcross contamination rates from 19.1 to 8.7% and substantially increased worker productivity. Application of sugar solution to the female flowers immediately prior to pollination increased yield of sound seeds per spike. Additional improvements to the pollination protocols are discussed. [ABSTRACT FROM AUTHOR]

Even with advanced gene technologies continued population improvement remains a key foundation for future genetic gain in forest trees. Currently, this is served by maintaining genetic diversity while capturing genetic improvement, often through structuring populations into a genetic hierarchy, setting population sizes, and managing pedigrees and inbreeding. In the future, information from genomic technologies will complement classical approaches, such as common-garden field experiments, for characterizing the genetic base and measuring and monitoring genetic diversity. This will entail directly measuring DNA sequence diversity of both selectively neutral markers and functional genes. Calibrating neutral marker diversity against functional diversity will become easier with functional genomics. For maintaining pedigree and managing inbreeding, genomic information can be used to relax some traditional tenets of population management. With future knowledge of functional polymorphisms, the better understanding of the nature and origins of genetic variation should enhance management of populations to both conserve genetic diversity and exploit it by more efficient selection. Where fungal diseases threaten biotic crises, very large populations may be needed, the requisite sizes often being very uncertain. Gene discovery holds enormous promise, but depends heavily on comparative genomics, capitalizing on genomic information from Arabidopsis, Populus and Eucalyptus, and the increasing numbers of accessible ESTs. Much greater insights into non-codon mutational processes and rates should also guide population management. A key challenge, however, will be to utilize information and apply tools cost-effectively. Also, very detailed genomic information, exemplified by the poplar-genome sequencing, may allow earlier adaptation of technology and development of new information in angiosperms than in gymnosperms. [ABSTRACT FROM AUTHOR]

Gene flow is a critical determinant of population genetic structure, playing an important role in both evolutionary and applied plant population genetics. Four methods have been used to estimate rates of gene flow among plant populations. I review and reconcile the data collected by these methods. The following generalization emerges: although gene flow varies substantially among species, populations, seasons, and even individual plants, at physical isolation distances of hundreds to thousands of meters, gene flow levels are frequently sufficient to counteract genetic drift and moderate levels of directional selection. This pattern suggests the genetic structure of natural plant populations is more dynamic than generally supposed. Furthermore, substantial and variable gene flow has implications for plant breeding, conservation genetics, and the potential for the escape of engineered genes. [ABSTRACT FROM AUTHOR]

Fifty-two clones in twenty-two full-sib families were represented in a field trial. All cuttings were taken from hedged ortets which were four years from seed, but had been cut back periodically to one metre high since age two. One-year-old seedlings, from a seed orchard, where most of the parents of the clones were represented, were used as controls. The trial was assessed for Dothistroma needle blight infection six years after planting. The mean infection level of all the cuttings was 21.1%, compared to 29.8% for the seedlings. This difference was attributed to the greater maturation age of the cuttings. It was calculated that if the best 10% of the clones were selected, infection could have been further reduced to 12%, a level where other disease control measures would be considered unnecessary. [ABSTRACT FROM AUTHOR]

Eighteen bioclimatic factors were estimated for 315 locations within the natural distribution of Acacia mearnsii. These climatic data were used to classify the locations into 12 groups, which formed the basis for selecting 22 provenances. It was concluded that the method can assist in identifying environmental variability within a species' natural distribution and ensure that the range of climatic conditions are appropriately sampled. [ABSTRACT FROM AUTHOR]

Twenty-three Pinus radiata seed orchard clones of the New Zealand '850' series were each control-pollinated with a mix of 10 pollens to produce polycross families. The seed was sown in open nursery beds. Seedlings were potted up at six times of the year and subjected to white advective frosts in controlled-environment rooms, with up to seven frosting runs of variable severities at each time. There were significant differences ( p< <0.001) between families in frost injury, such that, although there was statistically significant family × time interaction, some families were consistently more frost resistant (tolerant) than others. No association between frost resistance and growth rate was evident. Individual-tree heritability estimates for frost damage scores were around 0.3 at given times, and 0.20 over all times. Prospective gain in resistance from progeny testing over several seasons of the year, with 2:23 selection, is about 1°C. An additional gain of 0.4°C resistance appears obtainable from 1:90 selection of individuals within pair-crosses in a single frosting run. This additional (within-cross) gain might be increased to around 0.75°C, with the same culling rate but testing one ramet per seedling at each of four times of the year. [ABSTRACT FROM AUTHOR]