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Dag Lindgren - One of the best experts on this subject based on the ideXlab platform.
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Seed Orchards and Aspects on Supporting Tree Breeding
Challenges and Opportunities for the World's Forests in the 21st Century, 2013Co-Authors: Dag LindgrenAbstract:The main quantitative output and work horse for plant breeding today and accumulated efforts since half a century is Seed Orchards. This document do not cover deployment of vegetatively propagated material or control crosses (less than 2 % of number of Swedish forest plants produced) or GMO or genomic based selections (zero plant production) and focus mainly on Sweden. Seed Orchards established now are mainly with tested grafted clones. With Norway spruce, where vegetative propagation of young plants is easy, current testing and Seed orchard deployment is based on testing clonal performance. For Scots pine it is progeny tested clones, but progeny testing is a painfully slow and seemingly inefficient procedure. The number of clones is typically 20 or slightly more when clones are unrelated. It is more efficient to deploy clones in different proportions and it is not economic to strive for equal proportions. Pollen contamination is an important aspect of Seed Orchards, a practical remedy has not been found. However, Seed orchard crops from genetically young Seed Orchards with 100 % contamination are still better than crops from mature but genetically outdated alternatives. Earlier deployed clones were unrelated, but it seems to become inefficient avoiding related clones after the first generations. Genetic thinning is rare and difficult to defend from a gain point of view, but selective harvesting becomes increasingly common. The breeding population (typically 1,000) is shared in compartments (typically 50) and Seed Orchards draw on several compartments. Probably both Seed Orchards and breeding would benefit from a larger “breeding population”. There would be advantages if breeding efforts and Seed orchard establishment could be better synchronized. New cohorts of recently selected clones should be deployed to pine Seed Orchards more often, they tend to be genetically worn out and expensive to harvest. Projections of the impact of Seed Orchards on the national forest harvest almost a century ahead in Sweden is 10 % assuming no technology change. The possible “ecological risks” with the Seed orchard technology seem a small addition to that of plantation forestry.
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annual fertility variation in clonal Seed Orchards of teak tectona grandis l f and its impact on Seed crop
Silvae Genetica, 2009Co-Authors: A Nicodemus, M Varghese, B Nagarajan, Dag LindgrenAbstract:Fertility variation was studied in two clonal Seed Orchards (CSO) of teak in four consecutive years (2003‐2006). Both Orchards were raised in 1976 with grafts of phenotypes selected for growth and form. The Seed Orchards of CSO I (Topslip, Tamil Nadu State) and CSO II (Walayar, Kerala State) have 15 and 20 clones, respectively, with 13 common clones. The proportion of flowering ramets was generally low ranging from 16 to 53% across years. The best fruit yield during the study period was around 18 kg ha ‐1 in CSO I and 17 kg ha ‐1 in CSO II. Highly significant clonal variation and clone by year and clone by site interactions were observed for fertility traits. The clonal contribution was more skewed in poor flowering years than in abundant flowering years and in CSO II than in CSO I. Broad sense heritability for flower and fruit production per tree was low to moderate (0.16 to 0.55). Flower and fruit production by individual ramets in successive years were positively correlated. Correlations between reproductive and growth traits were generally low, but correlation was strong between flowering and fruiting. Fertility variation and group coancestry were higher in poor flowering years than in abundant years and in CSO II than CSO I. Restricting Seed collection to abundant flowering years, adjusting ramet number to balance contribution of clones and mixing of Seeds from successive years are suggested to reduce relatedness among orchard progeny. The usefulness of low input breeding options for teak like Seed production areas are also discussed.
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Unequal deployment of clones to Seed Orchards by considering genetic gain, relatedness and gene diversity
Forestry, 2009Co-Authors: Dag Lindgren, Darius Danusevičius, Ola RosvallAbstract:Summary Related clones in Seed Orchards lead to inbreeding depression and reduced genetic value of the Seeds. This study aims to develop the methodology for deployment of related clones to Seed Orchards when the breeding value and the pedigree are available for each candidate. The following goals were considered: high genetic gain, high genetic gain adjusted for predicted inbreeding depression (net gain), high gene diversity, and high effective clone number. The selection strategies included truncation selection with or without relatedness restrictions, maximizing genetic gain (linear deployment) with or without restrictions on relatedness and maximizing net gain. The selection strategies were applied to Norway spruce Seed orchard candidates evaluated in clonal tests. The material comprised full-sib and half-sib relationships. Comparisons were made both at the same gene diversity and at the effective clone number. Maximizing net gain by unequal ramet number deployment resulted in considerable higher net gain and a considerable reduction of related ramets in many comparisons. Linear deployment restricted against related clones compared at the same status number resulted in almost as high net gain. Reduction in gene diversity may be a more important reason to avoid relatives in Seed Orchards than the subsequent inbreeding for achieving a high net gain.
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variation in cone and Seed characters in clonal Seed Orchards of pinus sylvestris
New Forests, 2008Co-Authors: Nebi Bilir, Dag Lindgren, Finnvid Prescher, Johan KroonAbstract:Cone and Seed characters were observed on top, middle and bottom portions of tree crown in 3 ramets/clone in three Turkish Pinus sylvestris Seed Orchards. Broad sense heritability (clonal repeatability), and correlations among characters were estimated. Around one quarter of the Seed production occurred in the top portion, half in the middle and one quarter in the bottom portion of the crown for all Orchards. The percentage of filled Seeds varied little with the crown position, indicating more or less similar levels of selfing in the bottom of the crown as in the top. The Seed weight was typically 11 mg. Differences were found for studied cone and Seed characters among Orchards and crown positions. Variation among grafts within clone was higher than among clones for most characters. The heritability was on average below 0.5 (e.g., cone diameter, number of filled Seed per cone) and rarely rose above that (e.g., cone form, length/diameter; percentage of filled Seed) for any individual characters. The coefficient of variation within clones was often higher than among clones. Thus, non-genetic factors seem often more important for the variation in performance of grafts than their genetic constitution. Cone form (length/diameter) was the character where the clone influence was the strongest. Cone number and cone dry weight showed significant correlations with Seed characters (numbers of total and filled Seed, percentage and weight of filled Seeds). Significant correlation was found between Seed characters.
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optimum lifetime for swedish picea abies Seed Orchards
New Forests, 2008Co-Authors: Yoshinari Moriguchi, Finnvid Prescher, Dag LindgrenAbstract:The optimum lifetime of Picea abies Seed Orchards in Sweden was calculated using a model which considers changes in Seed yield over time, annual progress of genetic gain, establishment, management and Seed costs, and both the monetary and genetic value of the Seeds produced. The longer the Seed orchard is active, the more genetically outdated the produced Seeds will become, and thus their value will decline with time. A main scenario was constructed using the best available estimates for Swedish Norway spruce and was compared to various alternatives reflecting likely variations. The optimal lifetimes in all of these scenarios was in the order of 40 years. Sensitivity analyses showed that use of Orchards for slightly more or less than their optimal lifetimes does not lead to large losses. A more effective tree breeding program could slightly reduce the optimal lifetimes. The optimal lifetime depends strongly on the relationship between monetary value and genetic gain. Thus, in cases where genetic progress is sufficiently rapid, the optimal lifetime may be less than 30 years.
D. Lindgren - One of the best experts on this subject based on the ideXlab platform.
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Deployment of clones to Seed Orchards when candidates are related.
2008Co-Authors: D. Lindgren, Darius DanusevičiusAbstract:This paper deals with deployment of clones to Seed Orchards in situations when the candidates are relatives. Possible strategies comprise finding the best solution by an advanced computer algorithm, restricting against relatives and neglecting relatedness. Linear deployment versus truncation was considered. The value of application of a strategy has to be quantitatively defined to make comparisons among strategies; here it was defined as “Net gain”, considering predictions of breeding values, inbreeding depression, gene diversity (status number) and effective number. The efficiency of the strategies was studied in a (ideal) population of candidates composed of half-sib families. Results showed that, if the number of families available is considerable higher than the number of desired selections a close to optimal and simple strategy is to restrict against any relatedness and deploy the single best individual from the best families by linear deployment. Otherwise a more sophisticated algorithm is suggested. Here it is suggested that the simpler procedure can be used when the status number of the candidate population is 8 times higher than the status number of the clone deployment suggested. It is suggested that the effect by relatedness on gene diversity is more constraining on the extent of relatives in Seed Orchards than the inbreeding depression following mating of relatives. Introduction When tree breeding has passed its infancy, the option arises to select related clones to Seed Orchards. One way out of this dilemma is to structure the breeding population in unrelated compartments and select one clone from each (Lindgren and Gregorius 1976). However, this strategy has disadvantages. It is a restriction on selection and the best related selection is likely to have a much larger breeding value than the best unrelated. Inbreeding is a problem in the breeding population, it is an additional cause of variation and it reduces the variance available for selection. The consequences of restricting against relatives in Seed Orchards become more severe and annoying as breeding continues over generations. A limited number of relatives in a Seed orchard has only a small and may be neglectable negative effect (Olsson 2001). This study deals with how the deployed proportion of each candidate clone can be decided at the establishment of a Seed orchard when the breeding values are available for each candidate in a population of half-sib families. Conventional Seed orchard deployment strategies relied on simple truncation selection: selecting the candidates with breeding values above a certain threshold and deploying the candidates in equal proportions. Lindgren (1974) showed that deployment of candidates proportionally to their breeding value is a more efficient approach. If the candidates are unrelated, the deployment of clones in proportions linearly related to their breeding value is the most efficient strategy to maximise genetic gain (Lindgren and Matheson, 1986). In advanced breeding cycles, however, the candidates tend to be related and the linear deployment strategy does not guarantee an optimum solution. The emphasis on breeding value of related candidates may increase relatedness, hence inbreeding in the orchard to harmful levels (Olsson, 2001; Wang Tongli et al. 2003). One simple approach to cope with the negative effects of relatedness is to introduce constraints on relatedness, such as restricting candidates to say, the one top-ranking individual per family and then use linear deployment for the ramet number. Is there a better deployment solution? The aim of the present study is to develop and investigate procedures to deploy tested, related genotypes to clonal Seed Orchards with variable numbers of ramets across a range of scenarios with simple relatedness patterns. Simulation procedures are used based on artificial data generated for half-sib families that provide the candidates pool for Seed Orchards. Results may help to guide forest tree breeders about the potential and application of the method over a range of circumstances. Material and methods The following deployment strategies were compared: (a) truncation selection by selecting the clones with the breeding values exceeding certain threshold and deploying equal number of ramets (Truncation strategy); (b) truncation selection by selecting only one best individual within each family (Truncation unrelated); (c) maximizing gain at a given effective clone number (Linear deployment); (d) linear deployment by selecting one best individual within each family (Linear deployment unrelated) and (e) maximizing net gain at a given gene diversity (Optimal proportions). Net gain was the target parameter to be maximized and was calculated as as the average breeding value of Seeds produced from the orchard with a deduction for the expected inbreeding due to matings between related clones: ∑ Θ − = i i P g p ID BVI ) * 1 ( , [4]
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Seed Orchards and Seed collection stands of Scots pine in Turkey.
2008Co-Authors: N. Bi̇li̇r, M.d. Ulusan, D. LindgrenAbstract:Scots pine (Pinus sylvestris L.) has 22 Seed Orchards covering 116 ha and 36 Seed collection stands (Seed stands) covering 4813 ha. The Seed Orchards had on average 5.6 ha and 21 years, 41 clones and 36 ramets per clone. The effective number of clones was on average 37.3, which is 91% of census number indicating that the clones are represented by similar number of ramets. The stands had 134 ha, 1660 m. altitude, 105 years, 26 m. height, 35 cm diameter on average, were briefly documented in this study. Seed Orchards in Turkey usually draw their clones from a single Seed collection stand. Although it was changed for years based on annual plantation program, at beginning of the century more than 90 % of Seed demand for forest plantation in Turkey was covered from the Seed stands for some years, and the impact of Seed orchard crop is raising. There were large differences for number of clone and ramets per clone and total number of ramets among the Orchards. Large differences for the documented characters were also found among the Seed stands. Results of the study were discussed based on Seed source management and breeding programs.
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Optimal Clone Number for Seed Orchards with Tested Clones
Silvae Genetica, 2005Co-Authors: D. Lindgren, Finnvid PrescherAbstract:The optimal number of clones in Seed Orchards is discussed. A model is constructed to maximize a goodness criterion (“benefit”) for Seed Orchards. This criterion is a function of: 1) the number of tested genotypes available for selection and planted in Seed orchard; 2) the contribution to pollination from: a) the ramet itself; b) the closest neighbors; c) the rest of the orchard and sources outside the orchard (contamination); 3) variation among genotypes for fertility; 4) frequency of selfing; 5) production of selfed genotypes; 6) gene diversity (= status number); 7) influence of contamination; 8) genetic variation
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Balancing genetic gain and relatedness in Seed Orchards
Silvae Genetica, 2001Co-Authors: T. Olsson, D. LindgrenAbstract:The traditional way to avoid related mating and subsequent inbreeding depression in Seed Orchards is to use only unrelated clones for orchard establishment. As tree-breeding programs move to advanced generations, relatedness (coancestry) among candidates for Seed orchard selections becomes more common, especially for high breeding value candidates. The traditional way of selecting the ones with the highest breeding value, provided they are unrelated, is referred to Restricted Selection (RS). In order to consider breeding value as well as relatedness, an alternative selection method, based on a value criterion for the whole group of selected clones, is presented in this paper. The method, here called Group Merit Selection (GMS), is based on a suggestion by LINDGREN and MULLIN (1997), but modified for Seed orchard selection by neglecting selfing and self-coancestry. The method can be regarded as the selection of a group of clones that maximizes expected genetic value (predicted genetic gain minus inbreeding depression). A case study was conducted in which twenty clones for a Seed orchard were selected among second-generation loblolly pine (Pinus taeda L.) selections from the NCSU-Industry cooperative breeding program. Assuming an observed inbreeding depression of 40% for one unit coefficient of inbreeding, penalty constants based on estimated breeding values at age 8 was corresponding with inbreeding depression. That gave 12% more genetic value for GMS than Restricted Selection. Predictions of the penalty constant considering additional relevant factors (such as pollen contamination, breeding values based on immature trials, and unrepresentative experimental sites) resulted in selection of the same clones. Changes among the selected clones did not occur until relatedness reached twice the penalty constant, suggesting that GMS solutions are rather robust.
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fertility variation and its effect on the relatedness of Seeds in pinus densiflora pinus thunbergii and pinus koraiensis clonal Seed Orchards
Silvae Genetica, 1998Co-Authors: K S Kang, D. LindgrenAbstract:The numbers of female and male strobili were counted in clonal Seed Orchards with 99 clones of Pinus densiflora and 60 clones of P. thunbergii and in an archive consisting of 180 clones of P. koraiensis, respectively. The observation data showed a great variation in both female and male strobili among clones in the three populations. It was possible to express the expected contribution of genotypes to Seed crop as an inverse of cumulative function of type, x = F(x) 1/a , where x is the expected contribution of Seed orchard genotypes and F(x) is the ranked relative contribution of flowering production. Parameter a is a parameter which describes flowering variation. Status number and variance effective population size could be related to the square sum of contribution. The status numbers were calculated to be 69.2 (70% of the initial census number), 54.6 (91%) and 38.8 (22%) in the expected crops of clonal Seed Orchards of P. densiflora, P. thunbergii and P. koraiensis, respectively. The variance effective population sizes connecting these Orchards with their expected crops were estimated to be 230.3, 610.3 and 49.4, respectively. Despite the large differences in status numbers and variance effective population sizes, the group coancestry remained at a low value in all expected Seed orchard crops. Relative gene diversity compared to the reference population from which plus trees were selected was quite high in all populations.
W. Henkel - One of the best experts on this subject based on the ideXlab platform.
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A concept for Seed Orchards based on isoenzyme gene markers
Forest Ecology and Management, 2000Co-Authors: B. Hosius, F. Bergmann, M. Konnert, W. HenkelAbstract:Abstract Advanced silvicultural methods in Thuringia as well as the necessity to preserve the genetic resources of endangered tree species have led to the goal of establishing Seed Orchards of silver fir ( Abies alba Mill.). In order to combine several economic and genetic features in constructing these Seed Orchards, the clones were chosen using a multistep procedure accompanied by genetic surveys at isoenzyme loci. Of the initial material consisting of 26 indigenous stands, 500 plus-trees were selected according to their vitality and growth. Based on several sampling strategies where the clone collections were stratified according to the level of gene diversity, occurrence of rare alleles and degree of homozygosity, 130 clones were finally chosen from the plus-tree collection. These clones are assumed to include all essential features attributed to a Seed orchard which should produce vital and improved Seed crop and preserve the gene pool of silver fir.
Re Vaillancourt - One of the best experts on this subject based on the ideXlab platform.
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patterns of hybrid Seed production in adjacent Seed Orchards of acacia auriculiformis and a mangium in vietnam
Annals of Forest Science, 2019Co-Authors: Ce Harwood, Chi Q Nghiem, Rod A Griffin, Re VaillancourtAbstract:Hybrid Seed production in adjacent Seed Orchards of Acacia auriculiformis and Acacia mangium was influenced by (i) flowering times of the two species and (ii) the distances of parent trees from the inter-orchard boundary. Approximately 80% of hybridisation events were found within 60 m from the boundary. Understanding pollen dispersal has important implications for breeding and Seed production of pure species and hybrid Acacia. We examined patterns of hybrid production in adjacent clonal Seed Orchards of A. auriculiformis and A. mangium in Vietnam. We assessed the frequency of hybrid offspring using four species-diagnostic SSR markers in Seed collected from a total of 72 trees (75 Seedlings per tree) at distances ranging from 4 to 144 m from the inter-orchard boundary. The number of hybrid was determined from SSR allele peak sizes in pooled sample (10 Seedlings per pool, 540 pools). Calibrations were developed from pools with known proportions of pure-species and hybrid material. Hybrid frequency differed significantly among individual clones (P < 0.001) but not between species (A. mangium = 3.4%, A. auriculiformis = 2.8%). Two late-flowering clones of A. auriculiformis yielded no hybrids. The level of interspecific hybridisation declined significantly (P < 0.001) with increasing distance, and no hybrid Seed was produced by trees located more than 116 m from the inter-orchard boundary. Pooling of tissue samples for analysis of species-specific DNA polymorphisms was an efficient, low-cost strategy for detecting hybrid genotypes among the offspring of pure-species parents, and a low rate of associated error was demonstrated. The inferred decline in inter-species pollen flow with increasing distance from the boundary between the two Orchards provides guidance for the design of hybridising Orchards and isolation requirements to prevent contamination of Seed Orchards by external pollen sources.
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Patterns of hybrid Seed production in adjacent Seed Orchards of Acacia auriculiformis and A. mangium in Vietnam
Annals of Forest Science, 2019Co-Authors: Son Le, Ce Harwood, Chi Q Nghiem, A. Rod Griffin, Re VaillancourtAbstract:Key message Hybrid Seed production in adjacent Seed Orchards of Acacia auriculiformis and Acacia mangium was influenced by (i) flowering times of the two species and (ii) the distances of parent trees from the inter-orchard boundary. Approximately 80% of hybridisation events were found within 60 m from the boundary. Context Understanding pollen dispersal has important implications for breeding and Seed production of pure species and hybrid Acacia . Aims We examined patterns of hybrid production in adjacent clonal Seed Orchards of A. auriculiformis and A. mangium in Vietnam. Methods We assessed the frequency of hybrid offspring using four species-diagnostic SSR markers in Seed collected from a total of 72 trees (75 Seedlings per tree) at distances ranging from 4 to 144 m from the inter-orchard boundary. The number of hybrid was determined from SSR allele peak sizes in pooled sample (10 Seedlings per pool, 540 pools). Calibrations were developed from pools with known proportions of pure-species and hybrid material. Results Hybrid frequency differed significantly among individual clones ( P
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Patterns of hybrid Seed production in adjacent Seed Orchards of Acacia auriculiformis and A. mangium in Vietnam
'Springer Science and Business Media LLC', 2019Co-Authors: Le S, Ce Harwood, Cq Nghiem, Ar Griffin, Re VaillancourtAbstract:AbstractKey message Hybrid Seed production in adjacent Seed Orchards of Acacia auriculiformis and Acacia mangium was influenced by (i) flowering times of the two species and (ii) the distances of parent trees from the inter-orchard boundary. Approximately 80% of hybridisation events were found within 60 m from the boundary. ContextUnderstanding pollen dispersal has important implications for breeding and Seed production of pure species and hybrid Acacia.AimsWe examined patterns of hybrid production in adjacent clonal Seed Orchards of A. auriculiformis and A. mangium in Vietnam.MethodsWe assessed the frequency of hybrid offspring using four species-diagnostic SSR markers in Seed collected from a total of 72 trees (75 Seedlings per tree) at distances ranging from 4 to 144 m from the inter-orchard boundary. The number of hybrid was determined from SSR allele peak sizes in pooled sample (10 Seedlings per pool, 540 pools). Calibrations were developed from pools with known proportions of pure-species and hybrid material.ResultsHybrid frequency differed significantly among individual clones (P A. mangium = 3.4%, A. auriculiformis = 2.8%). Two late-flowering clones of A. auriculiformis yielded no hybrids. The level of interspecific hybridisation declined significantly (P ConclusionPooling of tissue samples for analysis of species-specific DNA polymorphisms was an efficient, low-cost strategy for detecting hybrid genotypes among the offspring of pure-species parents, and a low rate of associated error was demonstrated. The inferred decline in inter-species pollen flow with increasing distance from the boundary between the two Orchards provides guidance for the design of hybridising Orchards and isolation requirements to prevent contamination of Seed Orchards by external pollen sources
S C Stewart - One of the best experts on this subject based on the ideXlab platform.
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simultaneous estimation of pollen contamination and pollen fertilities of individual trees in conifer Seed Orchards using multilocus genetic data
Theoretical and Applied Genetics, 1994Co-Authors: S C StewartAbstract:Seed Orchards of forest trees are established to produce genetically-improved Seed for reforestation. Genetic efficiency requires Seed Orchards to be (1) reproductively isolated form surrounding trees, (2) that there be similar fertilities among all orchard trees, and (3) minimum inbreeding. Each aspect of Seed orchard reproduction can be simultaneously estimated using the observed frequency of each multilocus gametic type contributed through fertilizing pollen and the expected multilocus gametic segregation frequencies of orchard tree and of the contaminating population. These genetic estimates are directly relevant to the genetics of the tree breeding program. The flexibility of sampling Seed — the basic data for these techniques — allows great scope for hypothesis testing, including tests of the accuracy of predictions of biophysical models of pollen movement. A simple example and a white spruce Seed orchard case study are presented to illustrate the estimation technique and to investigate its sensitivity.