The perception of foresters and forestry in most countries is that both are closely associated wi... more The perception of foresters and forestry in most countries is that both are closely associated with timber harvesting and forest exploitation. Despite evidence to the contrary, foresters are not viewed as champions of environmental management. The practice of forestry is increasing in complexity at the economic, operational, environmental and social scales. The ideas for these complex changes are not new
AGRIS record. Record number, SK1998000651. Titles, Provenance variation, genotype by environment ... more AGRIS record. Record number, SK1998000651. Titles, Provenance variation, genotype by environment interactions and age - age correlations for Eucalyptus regnans on nine sites in south-eastern Australia. Personal Authors, ...
Thinned and pruned plantation-grown Eucalyptus nitens (H.Deane & Maiden) Maiden has potential to ... more Thinned and pruned plantation-grown Eucalyptus nitens (H.Deane & Maiden) Maiden has potential to supplement native forest 'ash' eucalypt logs for the Tasmanian sawmilling industry. Processing methods developed for native forest euca-lypts were applied to logs from 22-year-old pruned stands thinned at age six years to 100, 200, 300, 400 stems/ha and unthinned control stands with a stocking of 700 stems/ha at harvest. Consistent with existing industry requirements for the two sawing methods, 42 trees with diameter at breast height over bark (DBHOB) < 43 cm were selected for back-sawing (fl at-sawing), and 39 trees with DBHOB > 43 cm for quarter-sawing. For each sawing method, sets of trees were selected to provide trees evenly distributed across the target diameter range and, as near as possible, with sets matched across thinning treatments for size. From each tree two sawlogs, nominally 2.7 m in length, were cut from the pruned part of the stem. Both logs from individua...
Primeros resultados de un ensayo de severidad de poda en Eucalyptus regnans: efectos 1 en el crec... more Primeros resultados de un ensayo de severidad de poda en Eucalyptus regnans: efectos 1 en el crecimiento y respuesta fisiológica. 2 Peter 3 4 5 6 7 RESUMEN 8 Las crecientes preocupaciones de los consumidores en materias ambientales han llevado a la protección 9 de los bosques naturales. Como resultado, los productores de maderas de alto valor han dirigido su 10 interés a las plantaciones de Eucalyptus como una fuente para el suministro de madera de latifoliadas 11 que tradicionalmente se obtenía de bosques naturales. Varias especies de Eucalyptus se han establecido 12 en diversos países desde los trópicos hasta las zonas de clima templado frío. Una especie de interés en 13 la zona fría y templada, es E. regnans, que se ha establecido con éxito en Nueva Zelanda y Chile. En su 14 medio natural, los bosques esclerófilos húmedos del sureste de Australia, puede alcanzar alturas 15 cercanas a 100 metros y es una de las maderas más populares para una amplia gama de productos, 16 incluidos ...
The photosynthetic response to pruning was measured in two Eucalyptus regnans stands, aged 2 and ... more The photosynthetic response to pruning was measured in two Eucalyptus regnans stands, aged 2 and 3 years, located in areas of high productivity on the coast of the province of Arauco, Chile. Variables such as rates of CO 2 assimilation and stomatal conductance were measured in three ages of foliage on trees with different pruning severity treatments, which corresponded to the removal of 0 % (control), 30, 50 and 70 % of live crown length. The 2-year-old stand measurements were performed at the time of pruning and 6, 10, 14 and 18 weeks later, and the 3-year stand, 5, 9, 18 and 28 weeks after pruning. In both trials, significant differences were found between the foliage ages for all instances of measurement showing the mature foliage the highest values up to 30 % higher than old foliage. There were also significant differences between pruning severity treatments in both trials in which, in general, the highest values of CO 2 assimilation were observed among the highest pruning severity treatments with values up to 40 % higher than the unpruned trees.
... thinning operations open the canopy to wind penetration and can dramatically increase the vul... more ... thinning operations open the canopy to wind penetration and can dramatically increase the vulnerability of a stand to windthrow (Savill, 1983; Ruel, 1995; Quine ... The incidence of windthrow has been positively related to the rate of thinning (Ruth and Yoder, 1953; Booth, 1974). ...
Abstract Peripheral longitudinal growth strain (LGS) was measured on a total of 81, 22-year-old p... more Abstract Peripheral longitudinal growth strain (LGS) was measured on a total of 81, 22-year-old pruned Eucalyptus nitens trees from five thinning treatments in a plantation thinning trial in Tasmania. Growth strain data were gathered at breast height on each tree using the ...
Effective nutrition management is vital for optimising productivity in many eucalypt plantations,... more Effective nutrition management is vital for optimising productivity in many eucalypt plantations, to protect the large investment in pruning for solid wood production and meet long-term woodflow targets. A fertiliser decision support tool, EucFERT, has been developed which is helping forest managers to maximise growth responses while being economic and minimising off-site nutrient losses. The tool uses detailed local soil information along with crop and site data to provide guidance on a stand basis. Predicted growth responses to fertiliser are based on long-term nutrition experiments covering early-rotation and mid-rotation trials across a range of site and soil types. Outputs from EucFERT can be used to prepare Stand fertiliser management plans that include soil and site management, fertiliser product, rate, application, frequency and timing, along with environmental and operational cautions relating to aerial application. The use of this computerised tool provides much greater co...
Intra-specific hybrids within Eucalyptus nitens and E. globulus were compared directly with inter... more Intra-specific hybrids within Eucalyptus nitens and E. globulus were compared directly with inter-specific E. nitens × globulus using common parents. Diameter (age 2, 4, 6, 10 years) and Pilodyn (age 6 years) were used as indirect measures of growth and wood density, respectively. Genetic parameters were estimated for all cross types and traits. A direct comparison of the general combining ability with the general hybridising ability was made. Heterosis was estimated for intra- and inter-specific hybrids. The intra-specific hybrids in both species exhibit intermediate heritabilities and levels of additive genetic variance. The inter-specific F1 E. nitens × globulus exhibited high incidence of abnormalities at young ages and high levels of later age mortality. The mean performance of surviving inter-specific F1 hybrids was generally intermediate for all traits, to varying degrees, between the parental intra-specific crosses, and there is little evidence for significant heterosis. Different provenances of E. globulus may exhibit different responses to hybridisation. In this case, the inter-specific F1 hybrids, using Taranna E. globulus, appear to perform worse on average than those using King Island provenance for growth traits. There is evidence that specific hybrid families are produced that outperform most of the pure species families for one or other of the traits examined; however, there is no reliable quantitative genetic method of predicting which parents should be used.
This thesis examines the quantitative genetics of intra- and inter-specific hybrids of E. globulu... more This thesis examines the quantitative genetics of intra- and inter-specific hybrids of E. globulus ssp. globulus and E. nitens. The trials established to make this study are unique in forestry, due to the fact that the same parents have
been used in open-pollination, intra- and inter-provenance (or intra-species) crosses and inter-species F1 hybrids. This has allowed direct comparison of genetic parameters derived from different cross types. The traits examined
include frost resistance using an electrical conductivity method, growth (diameter at breast height over bark DBHOB, at ages 2, 3, 4, 6 and 10 years) and Pilodyn penetration at age 6 years as an indirect measure of wood density.
The results demonstrate that the measured performance of frost, growth and Pilodyn traits in the inter-specific Fi hybrid E. nitens x globulus is always intermediate or comparable with one or other of the parent species. In the frost trait, the inter-specific hybrid was no better than the frost sensitive E.
globulus, so there is no overall advantage in producing the hybrid for this trait. Negative mid-parent heterosis was observed for early age growth traits in inter-specific E. nitens x globulus FI hybrids involving Taranna E. globulus male
parents. The inter-specific FI hybrids demonstrated generally poor survival and a high proportion of abnormal and slow growing phenotypes, which eventually died. This latter phenomenon was not evident in pure species crosses, either within or between provenances. It is shown that in E. globulus open-pollinated progeny estimates of additive
genetic parameters are inflated and that breeding values for growth in E. globulus are poorly estimated, possibly due to the confounding effects of variation in inbreeding. This was not the case for traits of high heritability such as Pilodyn. Within the E. nitens population studied, open-pollinated estimates compared well with control-pollinated estimates for all traits. Genetic parameter estimates from control-pollinated progeny indicate low heritability for growth in E. globulus which diminish over time. Dominance
effects were low and comparable with additive genetic effects but were site specific. In E. nitens heritability for growth is moderate to high, tending to increase over time with significantly low levels of dominance, which diminish over time. Pilodyn has low to moderate heritabilities with low levels of dominance in both species. Moderate levels of heritability were demonstrated for frost resistance in both species, but dominance effects could not be accurately estimated. The correlation of performance of parents in intia-specific crosses through their General Combining Ability (GCA) is compared with performance in inter-specific hybrids through General Hybridising Ability (GHA). It is shown that there is little or no correlation between GCA and GHA in inter-specific F1 hybrids for growth or frost resistance, but there was a good correlation for Pilodyn. This indicates that, for growth and frost resistance, there may be
different genes, which contribute to expression between species and these may not combine according to classical quantitative genetic theory. In contrast, within E. globulus there was very high correlation of within-provenance GCA
with between-provenance GHA for growth and Pilodyn, indicating the same genes are acting within the species, regardless of provenance. It is demonstrated that standard quantitative genetic models do not cope adequately with inter-specific F1 hybrid populations for growth traits in this
case. In addition, the implication for breeding and deployment of interspecific Fi hybrids is compromised by the lack of ability to predict performance of potential hybrid combinations from pure species performance of parents.
The first Europeans to discover Eucalyptus globulus were French explorers in 1792. Its seed was r... more The first Europeans to discover Eucalyptus globulus were French explorers in 1792. Its seed was rapidly spread throughout the world in the 19 th century and this was the species by which much of the world first knew the genus. However, it was in the industrial forests of the 20 th century that this species, once considered the 'Prince of Eucalypts', achieved greatest prominence due to its fast growth and superior pulp qualities. Formal breeding first commenced in 1966 in Portugal and in the late 1980's large base population trials from open-pollinated seed collections from native stands were established in many countries. These trials have provided unprecedented insights into the quantitative genetic control of numerous traits of economic and ecological importance and how this variation is spatially distributed in the native range of the species. However with large, fully pedigreed breeding populations becoming available for quantitative analysis and the rapidly expanding knowledge of DNA sequence variation, we are now at the threshold of a new understanding of this important eucalypt gene pool. Indications of the significance of non-additive genetic effects are becoming available. The E. globulus chloroplast genome has now been sequenced and several genome maps have been published. Studies of the variation in nuclear microsatellites and the lignin biosynthesis gene CCR confirm the complex, spatially structured nature of the native gene pool. Strong spatial structuring of the chloroplast genome has provided a tool for tracking seed migration and the geographic origin of exotic landraces. Highly divergent lineages of chloroplast DNA have been discovered and studies of the hypervariable J LA+ region argue that some components of the E. globulus gene pool have been assimilated from other species following hybridisation.
The use of hybrid eucalypts in commercial forestry has generally resulted from opportunistic cros... more The use of hybrid eucalypts in commercial forestry has generally resulted from opportunistic crossing events with superior individuals being vegetatively propagated in large numbers. To develop strategies to breed hybrids, it is important to understand the barriers to hybridisation in the genus and as well as the genetic behavior of hybrid populations. Using F 1 hybrid populations of E. gunnii × globulus, E. nitens × globulus and outcrossed parental controls we demonstrate, firstly, the importance of environment on hybrid performance and secondly, that high levels of F 1 and advanced generation hybrid inviability can occur at an early age, even in crosses between closely related species. Inviable F 1 hybrids are a sensitive indicator of genomic incompatibility and add a cost to hybrid selection and production. However, surviving F 1 's may be vigorous and of interest to breeders. F 1 hybrid populations do not appear to conform to classical quantitative genetic models for growth with inflated estimates of additive genetic variance and poor predictability of hybrid performance. Nevertheless, this does not appear to be so for other more highly heritable traits. Advanced generation hybridisation is one means of overcoming the constraints and costs of poor clonal propagation and F 1 hybrid seed production, but hybrid breakdown may substantially reduce genetic gains.
Two Tasmanian provenance trials of Eucalyptus globulus Labili, and related species of blue gum—E ... more Two Tasmanian provenance trials of Eucalyptus globulus Labili, and related species of blue gum—E pseudoglobulus Naudin ex Maiden, E. bicostata Maid, et al., and E. maidenii F. Muell.—were analysed for growth, form and survival differences between species and between provenances within species. E globulus and E pseudoglobulus were not significantly different in growth but both were much faster growing than E bicostata and E maidenii which appeared to be poorly adapted to the cool temperate climate of Tasmania. Cross sites analysis did not identify significant consistent variation between provenances within species for height at age 4 years or diameter at age 7 years. Provenance differences were significant when sites were analysed separately although there was little differentiation within E globulus for growth characters. Significant differences were found in survival and form score between species and provenances within species. Implications for future work within this group of species are discussed.
in Vitro Cellular & Developmental Biology-plant, 1998
Genomic DNA was isolated fromin vitro Pinus radiata seedling with five DNA isolation protocols co... more Genomic DNA was isolated fromin vitro Pinus radiata seedling with five DNA isolation protocols commonly used for pines. The methods described by Jobes et al. (1995) and Nelson et al. (1994) utilize sodium dodecyl sulfate, whereas those of Murray and Thompson (1980), Doyle and Doyle (1990), and Devey et al. (1996) use cetyltrimethyl ammonium bromide for cell lysis. The quality and quantity of the isolated DNA was measured and compared. Lithium chloride was found to be more effective than RNase for minimizing the amount of RNA present in the solution. Protocols described by Jobes et al. (1995) and Devey et al. (1996) yielded a large quantity of pure DNA which was suitable for restriction enzyme digestion and polymerase chain reaction amplification. With these methods, 37 to 79 μg of DNA with an A260/280 ratio between 1.7 and 1.9 was obtained from 1 g ofPinus radiata seedlings grownin vitro.
The perception of foresters and forestry in most countries is that both are closely associated wi... more The perception of foresters and forestry in most countries is that both are closely associated with timber harvesting and forest exploitation. Despite evidence to the contrary, foresters are not viewed as champions of environmental management. The practice of forestry is increasing in complexity at the economic, operational, environmental and social scales. The ideas for these complex changes are not new
AGRIS record. Record number, SK1998000651. Titles, Provenance variation, genotype by environment ... more AGRIS record. Record number, SK1998000651. Titles, Provenance variation, genotype by environment interactions and age - age correlations for Eucalyptus regnans on nine sites in south-eastern Australia. Personal Authors, ...
Thinned and pruned plantation-grown Eucalyptus nitens (H.Deane & Maiden) Maiden has potential to ... more Thinned and pruned plantation-grown Eucalyptus nitens (H.Deane & Maiden) Maiden has potential to supplement native forest 'ash' eucalypt logs for the Tasmanian sawmilling industry. Processing methods developed for native forest euca-lypts were applied to logs from 22-year-old pruned stands thinned at age six years to 100, 200, 300, 400 stems/ha and unthinned control stands with a stocking of 700 stems/ha at harvest. Consistent with existing industry requirements for the two sawing methods, 42 trees with diameter at breast height over bark (DBHOB) < 43 cm were selected for back-sawing (fl at-sawing), and 39 trees with DBHOB > 43 cm for quarter-sawing. For each sawing method, sets of trees were selected to provide trees evenly distributed across the target diameter range and, as near as possible, with sets matched across thinning treatments for size. From each tree two sawlogs, nominally 2.7 m in length, were cut from the pruned part of the stem. Both logs from individua...
Primeros resultados de un ensayo de severidad de poda en Eucalyptus regnans: efectos 1 en el crec... more Primeros resultados de un ensayo de severidad de poda en Eucalyptus regnans: efectos 1 en el crecimiento y respuesta fisiológica. 2 Peter 3 4 5 6 7 RESUMEN 8 Las crecientes preocupaciones de los consumidores en materias ambientales han llevado a la protección 9 de los bosques naturales. Como resultado, los productores de maderas de alto valor han dirigido su 10 interés a las plantaciones de Eucalyptus como una fuente para el suministro de madera de latifoliadas 11 que tradicionalmente se obtenía de bosques naturales. Varias especies de Eucalyptus se han establecido 12 en diversos países desde los trópicos hasta las zonas de clima templado frío. Una especie de interés en 13 la zona fría y templada, es E. regnans, que se ha establecido con éxito en Nueva Zelanda y Chile. En su 14 medio natural, los bosques esclerófilos húmedos del sureste de Australia, puede alcanzar alturas 15 cercanas a 100 metros y es una de las maderas más populares para una amplia gama de productos, 16 incluidos ...
The photosynthetic response to pruning was measured in two Eucalyptus regnans stands, aged 2 and ... more The photosynthetic response to pruning was measured in two Eucalyptus regnans stands, aged 2 and 3 years, located in areas of high productivity on the coast of the province of Arauco, Chile. Variables such as rates of CO 2 assimilation and stomatal conductance were measured in three ages of foliage on trees with different pruning severity treatments, which corresponded to the removal of 0 % (control), 30, 50 and 70 % of live crown length. The 2-year-old stand measurements were performed at the time of pruning and 6, 10, 14 and 18 weeks later, and the 3-year stand, 5, 9, 18 and 28 weeks after pruning. In both trials, significant differences were found between the foliage ages for all instances of measurement showing the mature foliage the highest values up to 30 % higher than old foliage. There were also significant differences between pruning severity treatments in both trials in which, in general, the highest values of CO 2 assimilation were observed among the highest pruning severity treatments with values up to 40 % higher than the unpruned trees.
... thinning operations open the canopy to wind penetration and can dramatically increase the vul... more ... thinning operations open the canopy to wind penetration and can dramatically increase the vulnerability of a stand to windthrow (Savill, 1983; Ruel, 1995; Quine ... The incidence of windthrow has been positively related to the rate of thinning (Ruth and Yoder, 1953; Booth, 1974). ...
Abstract Peripheral longitudinal growth strain (LGS) was measured on a total of 81, 22-year-old p... more Abstract Peripheral longitudinal growth strain (LGS) was measured on a total of 81, 22-year-old pruned Eucalyptus nitens trees from five thinning treatments in a plantation thinning trial in Tasmania. Growth strain data were gathered at breast height on each tree using the ...
Effective nutrition management is vital for optimising productivity in many eucalypt plantations,... more Effective nutrition management is vital for optimising productivity in many eucalypt plantations, to protect the large investment in pruning for solid wood production and meet long-term woodflow targets. A fertiliser decision support tool, EucFERT, has been developed which is helping forest managers to maximise growth responses while being economic and minimising off-site nutrient losses. The tool uses detailed local soil information along with crop and site data to provide guidance on a stand basis. Predicted growth responses to fertiliser are based on long-term nutrition experiments covering early-rotation and mid-rotation trials across a range of site and soil types. Outputs from EucFERT can be used to prepare Stand fertiliser management plans that include soil and site management, fertiliser product, rate, application, frequency and timing, along with environmental and operational cautions relating to aerial application. The use of this computerised tool provides much greater co...
Intra-specific hybrids within Eucalyptus nitens and E. globulus were compared directly with inter... more Intra-specific hybrids within Eucalyptus nitens and E. globulus were compared directly with inter-specific E. nitens × globulus using common parents. Diameter (age 2, 4, 6, 10 years) and Pilodyn (age 6 years) were used as indirect measures of growth and wood density, respectively. Genetic parameters were estimated for all cross types and traits. A direct comparison of the general combining ability with the general hybridising ability was made. Heterosis was estimated for intra- and inter-specific hybrids. The intra-specific hybrids in both species exhibit intermediate heritabilities and levels of additive genetic variance. The inter-specific F1 E. nitens × globulus exhibited high incidence of abnormalities at young ages and high levels of later age mortality. The mean performance of surviving inter-specific F1 hybrids was generally intermediate for all traits, to varying degrees, between the parental intra-specific crosses, and there is little evidence for significant heterosis. Different provenances of E. globulus may exhibit different responses to hybridisation. In this case, the inter-specific F1 hybrids, using Taranna E. globulus, appear to perform worse on average than those using King Island provenance for growth traits. There is evidence that specific hybrid families are produced that outperform most of the pure species families for one or other of the traits examined; however, there is no reliable quantitative genetic method of predicting which parents should be used.
This thesis examines the quantitative genetics of intra- and inter-specific hybrids of E. globulu... more This thesis examines the quantitative genetics of intra- and inter-specific hybrids of E. globulus ssp. globulus and E. nitens. The trials established to make this study are unique in forestry, due to the fact that the same parents have
been used in open-pollination, intra- and inter-provenance (or intra-species) crosses and inter-species F1 hybrids. This has allowed direct comparison of genetic parameters derived from different cross types. The traits examined
include frost resistance using an electrical conductivity method, growth (diameter at breast height over bark DBHOB, at ages 2, 3, 4, 6 and 10 years) and Pilodyn penetration at age 6 years as an indirect measure of wood density.
The results demonstrate that the measured performance of frost, growth and Pilodyn traits in the inter-specific Fi hybrid E. nitens x globulus is always intermediate or comparable with one or other of the parent species. In the frost trait, the inter-specific hybrid was no better than the frost sensitive E.
globulus, so there is no overall advantage in producing the hybrid for this trait. Negative mid-parent heterosis was observed for early age growth traits in inter-specific E. nitens x globulus FI hybrids involving Taranna E. globulus male
parents. The inter-specific FI hybrids demonstrated generally poor survival and a high proportion of abnormal and slow growing phenotypes, which eventually died. This latter phenomenon was not evident in pure species crosses, either within or between provenances. It is shown that in E. globulus open-pollinated progeny estimates of additive
genetic parameters are inflated and that breeding values for growth in E. globulus are poorly estimated, possibly due to the confounding effects of variation in inbreeding. This was not the case for traits of high heritability such as Pilodyn. Within the E. nitens population studied, open-pollinated estimates compared well with control-pollinated estimates for all traits. Genetic parameter estimates from control-pollinated progeny indicate low heritability for growth in E. globulus which diminish over time. Dominance
effects were low and comparable with additive genetic effects but were site specific. In E. nitens heritability for growth is moderate to high, tending to increase over time with significantly low levels of dominance, which diminish over time. Pilodyn has low to moderate heritabilities with low levels of dominance in both species. Moderate levels of heritability were demonstrated for frost resistance in both species, but dominance effects could not be accurately estimated. The correlation of performance of parents in intia-specific crosses through their General Combining Ability (GCA) is compared with performance in inter-specific hybrids through General Hybridising Ability (GHA). It is shown that there is little or no correlation between GCA and GHA in inter-specific F1 hybrids for growth or frost resistance, but there was a good correlation for Pilodyn. This indicates that, for growth and frost resistance, there may be
different genes, which contribute to expression between species and these may not combine according to classical quantitative genetic theory. In contrast, within E. globulus there was very high correlation of within-provenance GCA
with between-provenance GHA for growth and Pilodyn, indicating the same genes are acting within the species, regardless of provenance. It is demonstrated that standard quantitative genetic models do not cope adequately with inter-specific F1 hybrid populations for growth traits in this
case. In addition, the implication for breeding and deployment of interspecific Fi hybrids is compromised by the lack of ability to predict performance of potential hybrid combinations from pure species performance of parents.
The first Europeans to discover Eucalyptus globulus were French explorers in 1792. Its seed was r... more The first Europeans to discover Eucalyptus globulus were French explorers in 1792. Its seed was rapidly spread throughout the world in the 19 th century and this was the species by which much of the world first knew the genus. However, it was in the industrial forests of the 20 th century that this species, once considered the 'Prince of Eucalypts', achieved greatest prominence due to its fast growth and superior pulp qualities. Formal breeding first commenced in 1966 in Portugal and in the late 1980's large base population trials from open-pollinated seed collections from native stands were established in many countries. These trials have provided unprecedented insights into the quantitative genetic control of numerous traits of economic and ecological importance and how this variation is spatially distributed in the native range of the species. However with large, fully pedigreed breeding populations becoming available for quantitative analysis and the rapidly expanding knowledge of DNA sequence variation, we are now at the threshold of a new understanding of this important eucalypt gene pool. Indications of the significance of non-additive genetic effects are becoming available. The E. globulus chloroplast genome has now been sequenced and several genome maps have been published. Studies of the variation in nuclear microsatellites and the lignin biosynthesis gene CCR confirm the complex, spatially structured nature of the native gene pool. Strong spatial structuring of the chloroplast genome has provided a tool for tracking seed migration and the geographic origin of exotic landraces. Highly divergent lineages of chloroplast DNA have been discovered and studies of the hypervariable J LA+ region argue that some components of the E. globulus gene pool have been assimilated from other species following hybridisation.
The use of hybrid eucalypts in commercial forestry has generally resulted from opportunistic cros... more The use of hybrid eucalypts in commercial forestry has generally resulted from opportunistic crossing events with superior individuals being vegetatively propagated in large numbers. To develop strategies to breed hybrids, it is important to understand the barriers to hybridisation in the genus and as well as the genetic behavior of hybrid populations. Using F 1 hybrid populations of E. gunnii × globulus, E. nitens × globulus and outcrossed parental controls we demonstrate, firstly, the importance of environment on hybrid performance and secondly, that high levels of F 1 and advanced generation hybrid inviability can occur at an early age, even in crosses between closely related species. Inviable F 1 hybrids are a sensitive indicator of genomic incompatibility and add a cost to hybrid selection and production. However, surviving F 1 's may be vigorous and of interest to breeders. F 1 hybrid populations do not appear to conform to classical quantitative genetic models for growth with inflated estimates of additive genetic variance and poor predictability of hybrid performance. Nevertheless, this does not appear to be so for other more highly heritable traits. Advanced generation hybridisation is one means of overcoming the constraints and costs of poor clonal propagation and F 1 hybrid seed production, but hybrid breakdown may substantially reduce genetic gains.
Two Tasmanian provenance trials of Eucalyptus globulus Labili, and related species of blue gum—E ... more Two Tasmanian provenance trials of Eucalyptus globulus Labili, and related species of blue gum—E pseudoglobulus Naudin ex Maiden, E. bicostata Maid, et al., and E. maidenii F. Muell.—were analysed for growth, form and survival differences between species and between provenances within species. E globulus and E pseudoglobulus were not significantly different in growth but both were much faster growing than E bicostata and E maidenii which appeared to be poorly adapted to the cool temperate climate of Tasmania. Cross sites analysis did not identify significant consistent variation between provenances within species for height at age 4 years or diameter at age 7 years. Provenance differences were significant when sites were analysed separately although there was little differentiation within E globulus for growth characters. Significant differences were found in survival and form score between species and provenances within species. Implications for future work within this group of species are discussed.
in Vitro Cellular & Developmental Biology-plant, 1998
Genomic DNA was isolated fromin vitro Pinus radiata seedling with five DNA isolation protocols co... more Genomic DNA was isolated fromin vitro Pinus radiata seedling with five DNA isolation protocols commonly used for pines. The methods described by Jobes et al. (1995) and Nelson et al. (1994) utilize sodium dodecyl sulfate, whereas those of Murray and Thompson (1980), Doyle and Doyle (1990), and Devey et al. (1996) use cetyltrimethyl ammonium bromide for cell lysis. The quality and quantity of the isolated DNA was measured and compared. Lithium chloride was found to be more effective than RNase for minimizing the amount of RNA present in the solution. Protocols described by Jobes et al. (1995) and Devey et al. (1996) yielded a large quantity of pure DNA which was suitable for restriction enzyme digestion and polymerase chain reaction amplification. With these methods, 37 to 79 μg of DNA with an A260/280 ratio between 1.7 and 1.9 was obtained from 1 g ofPinus radiata seedlings grownin vitro.
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Papers by Peter Volker
been used in open-pollination, intra- and inter-provenance (or intra-species) crosses and inter-species F1 hybrids. This has allowed direct comparison of genetic parameters derived from different cross types. The traits examined
include frost resistance using an electrical conductivity method, growth (diameter at breast height over bark DBHOB, at ages 2, 3, 4, 6 and 10 years) and Pilodyn penetration at age 6 years as an indirect measure of wood density.
The results demonstrate that the measured performance of frost, growth and Pilodyn traits in the inter-specific Fi hybrid E. nitens x globulus is always intermediate or comparable with one or other of the parent species. In the frost trait, the inter-specific hybrid was no better than the frost sensitive E.
globulus, so there is no overall advantage in producing the hybrid for this trait. Negative mid-parent heterosis was observed for early age growth traits in inter-specific E. nitens x globulus FI hybrids involving Taranna E. globulus male
parents. The inter-specific FI hybrids demonstrated generally poor survival and a high proportion of abnormal and slow growing phenotypes, which eventually died. This latter phenomenon was not evident in pure species crosses, either within or between provenances. It is shown that in E. globulus open-pollinated progeny estimates of additive
genetic parameters are inflated and that breeding values for growth in E. globulus are poorly estimated, possibly due to the confounding effects of variation in inbreeding. This was not the case for traits of high heritability such as Pilodyn. Within the E. nitens population studied, open-pollinated estimates compared well with control-pollinated estimates for all traits. Genetic parameter estimates from control-pollinated progeny indicate low heritability for growth in E. globulus which diminish over time. Dominance
effects were low and comparable with additive genetic effects but were site specific. In E. nitens heritability for growth is moderate to high, tending to increase over time with significantly low levels of dominance, which diminish over time. Pilodyn has low to moderate heritabilities with low levels of dominance in both species. Moderate levels of heritability were demonstrated for frost resistance in both species, but dominance effects could not be accurately estimated. The correlation of performance of parents in intia-specific crosses through their General Combining Ability (GCA) is compared with performance in inter-specific hybrids through General Hybridising Ability (GHA). It is shown that there is little or no correlation between GCA and GHA in inter-specific F1 hybrids for growth or frost resistance, but there was a good correlation for Pilodyn. This indicates that, for growth and frost resistance, there may be
different genes, which contribute to expression between species and these may not combine according to classical quantitative genetic theory. In contrast, within E. globulus there was very high correlation of within-provenance GCA
with between-provenance GHA for growth and Pilodyn, indicating the same genes are acting within the species, regardless of provenance. It is demonstrated that standard quantitative genetic models do not cope adequately with inter-specific F1 hybrid populations for growth traits in this
case. In addition, the implication for breeding and deployment of interspecific Fi hybrids is compromised by the lack of ability to predict performance of potential hybrid combinations from pure species performance of parents.
been used in open-pollination, intra- and inter-provenance (or intra-species) crosses and inter-species F1 hybrids. This has allowed direct comparison of genetic parameters derived from different cross types. The traits examined
include frost resistance using an electrical conductivity method, growth (diameter at breast height over bark DBHOB, at ages 2, 3, 4, 6 and 10 years) and Pilodyn penetration at age 6 years as an indirect measure of wood density.
The results demonstrate that the measured performance of frost, growth and Pilodyn traits in the inter-specific Fi hybrid E. nitens x globulus is always intermediate or comparable with one or other of the parent species. In the frost trait, the inter-specific hybrid was no better than the frost sensitive E.
globulus, so there is no overall advantage in producing the hybrid for this trait. Negative mid-parent heterosis was observed for early age growth traits in inter-specific E. nitens x globulus FI hybrids involving Taranna E. globulus male
parents. The inter-specific FI hybrids demonstrated generally poor survival and a high proportion of abnormal and slow growing phenotypes, which eventually died. This latter phenomenon was not evident in pure species crosses, either within or between provenances. It is shown that in E. globulus open-pollinated progeny estimates of additive
genetic parameters are inflated and that breeding values for growth in E. globulus are poorly estimated, possibly due to the confounding effects of variation in inbreeding. This was not the case for traits of high heritability such as Pilodyn. Within the E. nitens population studied, open-pollinated estimates compared well with control-pollinated estimates for all traits. Genetic parameter estimates from control-pollinated progeny indicate low heritability for growth in E. globulus which diminish over time. Dominance
effects were low and comparable with additive genetic effects but were site specific. In E. nitens heritability for growth is moderate to high, tending to increase over time with significantly low levels of dominance, which diminish over time. Pilodyn has low to moderate heritabilities with low levels of dominance in both species. Moderate levels of heritability were demonstrated for frost resistance in both species, but dominance effects could not be accurately estimated. The correlation of performance of parents in intia-specific crosses through their General Combining Ability (GCA) is compared with performance in inter-specific hybrids through General Hybridising Ability (GHA). It is shown that there is little or no correlation between GCA and GHA in inter-specific F1 hybrids for growth or frost resistance, but there was a good correlation for Pilodyn. This indicates that, for growth and frost resistance, there may be
different genes, which contribute to expression between species and these may not combine according to classical quantitative genetic theory. In contrast, within E. globulus there was very high correlation of within-provenance GCA
with between-provenance GHA for growth and Pilodyn, indicating the same genes are acting within the species, regardless of provenance. It is demonstrated that standard quantitative genetic models do not cope adequately with inter-specific F1 hybrid populations for growth traits in this
case. In addition, the implication for breeding and deployment of interspecific Fi hybrids is compromised by the lack of ability to predict performance of potential hybrid combinations from pure species performance of parents.