Seleção precoce para características de crescimento em testes clonais de Eucalyptus urophylla (original) (raw)
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2011
The aim of this study was to estimate genetic parameters for growth and stem form traits in a progenies test of Eucalyptus cloeziana, at 24 years of age, established in Luiz Antônio, SP. The trial was installed with open-pollinated seeds from 35 seed-trees from Helenvale and Cardwell St. Forest provenances, Australia. The trial was installed in a randomized block design, with single tree plots and 100 replications. The trial was measured at 24 years of age for diameter at breast height DBH, total height, volume and stem form. Significant differences among progenies were obtained for all traits. High genetic coefficients of variation and heritabilities were detected for all traits, showing a strong genetic control in the traits and the possibility to obtain genetic gains by massal selection among and within progenies. The expected genetic gains for stands with 24 years of age, growing in sites with the same environmental characteristics of Luiz Antônio and with seeds collected after ...
Revista Árvore, 2009
Espécies de rápido crescimento como as do gênero Eucalyptus apresentam sérios problemas durante as diversas fases de processamento de desdobro, secagem e beneficiamento. Assim, este trabalho objetivou estudar as propriedades físicas da madeira de um híbrido clonal de Eucalyptus urophylla x Eucalyptus grandis de duas idades, provenientes de regeneração florestal por talhadia simples e por reforma, em diferentes intensidades de desbaste, com diâmetros entre 28,0 e 30,0 cm. Os resultados indicaram que o extrato de maior idade com intervenção de dois desbastes (E2) apresentou os maiores valores médios da densidade básica ao longo do fuste e na direção medula-casca, além de menores contrações volumétricas médias e menor fator anisotrópico médio (1,66). Apesar de o extrato E1, com talhadia e 70 meses de idade, cujo fator anisotrópico médio foi igual a 1,92, ser próximo do extrato E3, em que foi realizada apenas uma reforma aos 70 meses de idade, com fator anisotrópico igual a 2,04 ao long...
Revista Arvore, 2009
The objective of this study was to compare the genetic gain estimates obtained by different selection strategies for identification of Eucalyptus grandis x Eucalyptus urophylla genotypes with specific environmental adaptation. The genetic progress obtained by mass selection, stratified mass selection, selection among and within families and combined selection was evaluated in three contrasting environments. Variance analysis showed a significant difference at 1% of probability according to the F test among the different genotypes evaluated in these three environments. This genetic divergence was observed in all the evaluated traits: diameter at breast height, plant height and wood volume, allowing inferring the existence of genetic variability among families. The hybrid population studied presents good yield potential and genetic variability to be explored by selection. The selection methods showed similar estimates of genetic progress, supporting the decision to use the most practical strategies.