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Quantitative Genetics on Hybrid Populations of Trees: Estimations of Genetic Parameters and Implications for Breeding Strategies.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Quantitative Genetics on Hybrid Populations of Trees: Estimations of Genetic Parameters and Implications for Breeding Strategies./
作者:	Ibarra Oyarzun, Luis Alejandro.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
面頁冊數:	168 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-09, Section: B.
Contained By:	Dissertations Abstracts International83-09B.
標題:	Precipitation. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28972990
ISBN:	9798780650034

Quantitative Genetics on Hybrid Populations of Trees: Estimations of Genetic Parameters and Implications for Breeding Strategies.
Ibarra Oyarzun, Luis Alejandro.

Quantitative Genetics on Hybrid Populations of Trees: Estimations of Genetic Parameters and Implications for Breeding Strategies. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 168 p.

Source: Dissertations Abstracts International, Volume: 83-09, Section: B.

Thesis (Ph.D.)--North Carolina State University, 2021.

This item must not be sold to any third party vendors.

Many combinations of hybrid trees have been made in the genera Eucalyptus and Pinus for the objectives of wood and cellulose production. In South Africa and Chile, field tests with hybrid populations of trees were established, and growth and wood properties measurements recorded. Quantitative genetic parameters were estimated, fitting a model that considers the effects of parent General Hybridizing Ability (GHA) for species A and B, and Specific Hybridizing Ability (SHA) for the combination of parents), along with Genetic x Environment interactions. In addition, a stochastic simulation of full-sib hybrid progeny tests was done with various mating designs and underlying true genetic parameters, where the target was to describe the accuracy and variation of the genetic parameter estimates.A clonal hybrid population of Eucalyptus nitens x E. globulus assessed in two breeding zones in Chile revealed large genetic variation in volume and wood properties. Significant genetic gain is possible for all traits analyzed. The E. nitens parent had a considerable impact on the volume gain of the hybrid, which implies that testing more E. nitens parents in future interspecific crosses will assure more volume gain. In contrast, E. globulus demonstrated zero GHA variance for volume, but did show important GHA variance for wood traits (Basic density (m3 /kg), Pulp Yield (%), and Specific Consumption (m3 /ADt)). In the Arauco zone, E. globulus demonstrated a large effect on the genetic variability of these traits; meanwhile, in the Valdivia zone, E. nitens and E. globulus were roughly similar in the size of the GHA variance. There was a strong relationship between parental performance in pure species crosses (GCA) and hybrid crosses (GHA), which indicates that parents could be selected for interspecific crosses based on pure species test results for volume and wood properties.In clonal and seedling hybrid populations of Pinus patula x P. tecunumanii (low elevation, TECL) in South Africa, a large impact of P. tecunumanii (TECL) was observed compared to P. patula. TECL exhibited higher GHA variance for volume gain in both populations. For new hybrid crosses, a more intense selection of parents should be made among TECL parents to increase volume gain. In a hybrid seedling population of P. patula x P. tecunumanii (high elevation) (PATxTECH), P. patula had a large impact on the volume gain and MOE, while TECH had a zero estimate of GHA variance for volume and a low GHA variance for MOE. Thus, more PAT parents should be tested in new hybrid crosses of this variety to increase volume and MOE gain.In the stochastic simulation, several scenarios with a range of genetic variances and mating designs were tested to understand which are optimum mating designs for obtaining unbiased and precise estimates of GHA and SHA variance. A combination of 24 parents tested in 4 crosses gave the most precise estimates for GHA and SHA variance. Zero GHA variance estimates are more likely to be obtained when a low number of crosses per parent are tested, especially in the presence of high SHA variance. For GHA variances, serious underestimates can be observed under some conditions. For example, in scenarios with a low number of parents and/or low number of crosses, the frequency of zero GHA variance estimates (despite non-zero true GHA variance) was as high as 11% over 1000 iterations. In the real data analyzed from the hybrid population of E. globulus x E. nitens and P. patula x P. tecunumanii (high elevation), zero GHA variance estimates were found for one of the species for volume; in both of those populations, the mating designs utilized a low number of parents and crosses (or the combination of both).

ISBN: 9798780650034Subjects--Topical Terms:

3680799
Precipitation.

Quantitative Genetics on Hybrid Populations of Trees: Estimations of Genetic Parameters and Implications for Breeding Strategies.
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245 1 0 $a Quantitative Genetics on Hybrid Populations of Trees: Estimations of Genetic Parameters and Implications for Breeding Strategies.
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300 $a 168 p.
500 $a Source: Dissertations Abstracts International, Volume: 83-09, Section: B.
500 $a Advisor: Hodge, Gary R. ;Acosta, Juan Jose;Maltecca, Christian;Payn, Kitt.
502 $a Thesis (Ph.D.)--North Carolina State University, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Many combinations of hybrid trees have been made in the genera Eucalyptus and Pinus for the objectives of wood and cellulose production. In South Africa and Chile, field tests with hybrid populations of trees were established, and growth and wood properties measurements recorded. Quantitative genetic parameters were estimated, fitting a model that considers the effects of parent General Hybridizing Ability (GHA) for species A and B, and Specific Hybridizing Ability (SHA) for the combination of parents), along with Genetic x Environment interactions. In addition, a stochastic simulation of full-sib hybrid progeny tests was done with various mating designs and underlying true genetic parameters, where the target was to describe the accuracy and variation of the genetic parameter estimates.A clonal hybrid population of Eucalyptus nitens x E. globulus assessed in two breeding zones in Chile revealed large genetic variation in volume and wood properties. Significant genetic gain is possible for all traits analyzed. The E. nitens parent had a considerable impact on the volume gain of the hybrid, which implies that testing more E. nitens parents in future interspecific crosses will assure more volume gain. In contrast, E. globulus demonstrated zero GHA variance for volume, but did show important GHA variance for wood traits (Basic density (m3 /kg), Pulp Yield (%), and Specific Consumption (m3 /ADt)). In the Arauco zone, E. globulus demonstrated a large effect on the genetic variability of these traits; meanwhile, in the Valdivia zone, E. nitens and E. globulus were roughly similar in the size of the GHA variance. There was a strong relationship between parental performance in pure species crosses (GCA) and hybrid crosses (GHA), which indicates that parents could be selected for interspecific crosses based on pure species test results for volume and wood properties.In clonal and seedling hybrid populations of Pinus patula x P. tecunumanii (low elevation, TECL) in South Africa, a large impact of P. tecunumanii (TECL) was observed compared to P. patula. TECL exhibited higher GHA variance for volume gain in both populations. For new hybrid crosses, a more intense selection of parents should be made among TECL parents to increase volume gain. In a hybrid seedling population of P. patula x P. tecunumanii (high elevation) (PATxTECH), P. patula had a large impact on the volume gain and MOE, while TECH had a zero estimate of GHA variance for volume and a low GHA variance for MOE. Thus, more PAT parents should be tested in new hybrid crosses of this variety to increase volume and MOE gain.In the stochastic simulation, several scenarios with a range of genetic variances and mating designs were tested to understand which are optimum mating designs for obtaining unbiased and precise estimates of GHA and SHA variance. A combination of 24 parents tested in 4 crosses gave the most precise estimates for GHA and SHA variance. Zero GHA variance estimates are more likely to be obtained when a low number of crosses per parent are tested, especially in the presence of high SHA variance. For GHA variances, serious underestimates can be observed under some conditions. For example, in scenarios with a low number of parents and/or low number of crosses, the frequency of zero GHA variance estimates (despite non-zero true GHA variance) was as high as 11% over 1000 iterations. In the real data analyzed from the hybrid population of E. globulus x E. nitens and P. patula x P. tecunumanii (high elevation), zero GHA variance estimates were found for one of the species for volume; in both of those populations, the mating designs utilized a low number of parents and crosses (or the combination of both).
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