Genetic parameters of intra- and inter-specific hybrids of Eucalyptus globulus and E. nitens |
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Authors: | Peter W Volker Bradley M Potts Nuno M G Borralho |
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Institution: | (1) Forestry Tasmania, 79 Melville St, Hobart, Tasmania, 7000, Australia;(2) Co-operative Research Centre for Forestry, Hobart, Tasmania, Australia;(3) School of Plant Science, University of Tasmania, Hobart, Tasmania, 7001, Australia;(4) Centro de Estudos Florestais, Universidade Técnica de Lisboa, Tapada da Ajuda, 1449-017 Lisbon, Portugal |
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Abstract: | 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. |
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Keywords: | Genetic parameters Eucalypts F1 hybrids |
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