Data/hora: 15/06/2024 15:52:18

Biblioteca(s): | Embrapa Florestas.
Data corrente: | 06/06/1995
Data da última atualização: | 24/03/2015
Autoria: | SHIMIZU, J. Y.
Título: | Inter-family competition in loblolly pine and its effects in genetic tests.
Ano de publicação: | 1985
Fonte/Imprenta: | 1985.
Páginas: | 64 f.
Idioma: | Inglês
Notas: | Thesis (Doctor of Philosophy) - Department of Forestry, Graduate Faculty, North Carolina State University, Raleigh.
Conteúdo: | Thirty -six unrelated full-sib families of Loblolly pine were used to evaluate the e of inter-family competition in genetic tests.Three-month-old seedlings were planted in a nursery with a uniform spacing of 8cm x 8cm in three plot layouts: a) 16-tree square plots; b)2-tree row plots; and c) non-contiguous family plots . Five levels of inter-family competition were identified according to the number of unrelated competitors in the immediate vicinity of a subject tree. Eight of the families were deleted from the analyses of growth traits because of empty plots due to mortality at 20 months of age which was apparently unrelated to increases in inter-family competition levels. Family differences in competitive ability were significant,especially for stem volume and dry weigt but less so for height growth . Low intraclass correlations for competitive ability in spite of the possible presence of non-additive genetic variance suggested that competitive ability is lowly hertitable. Higher levels of inter-family competition increased intracless correlations, indicating that interfamily competition leads to overestimation of family variances and of all parameters derived therefrom. Genetic phase changes during the stand development took place much earlier in more genotypically homogenous stands. Individual families reacted differentlly to inter-family competition at different stages of growth. Since competitive ability did not correlate with growth traits at competition levels other than the one in which it was observed and showed low heritability, selections under intense inter-family competition in short-term genetic tests are not likely to increase genetic gain. A few families showed rank changes under inter-family competition but neither the magnitude or the direction of the change could be preedicted on the basis of their performance in family blocks. Thinnings should become integral parts of loblolly pine genetic tests in order to reduce the bias in the estimation of genetic parameters and in ranking families for their genetic merit.
Palavras-Chave: | Competição; Competition; Genetic parameters; Mudas; Parametros genéticos; Viveiros florestais.
Thesagro: | Genética; Pinheiro; Pinus Taeda.
Thesaurus Nal: | forest nurseries; genetics; seedlings.
Categoria do assunto: | --
URL: | http://ainfo.cnptia.embrapa.br/digital/bitstream/item/120873/1/Doc1.pdf
Registro original: | Embrapa Florestas (CNPF)

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