M. D. V. de Resende

Seleção genética em progênies híbridas de coqueiro

O presente trabalho objetivou realizar a selecao genetica de individuos hibridos superiores de coqueiro a partir da avaliacao de 1.080 plantas para producao de frutos e de albumen fresco, visando a ao fornecimento de sementes e/ou clones melhorados para plantio no Para. Empregaram-se o delineamento experimental de blocos ao acaso e os metodos Blupis e Blupis-Biefeitos, visando identificar em quais parcelas estao os melhores individuos e quantos individuos devem ser selecionados de cada parcela. Foram avaliados os caracteres numero de frutos (NF), peso de albumen fresco por fruto (PAFF) e peso de albumen fresco por planta (PAFP), em nove safras anuais. As estimativas dos coeficientes de determinacao genetica entre medias de progenies variaram de 81,12% a 97,38%, propiciando acuracias seletivas de 90,07% a 98,68% para a selecao entre familias hibridas. A interacao familias x safras foi de grande magnitude para os caracteres NF e PAFP, conforme revelado pelas baixas (40,77% a 63,36%) correlacoes genotipicas atraves das safras. O procedimento Blupis - Biefeitos indicou a selecao de 66 plantas, sendo 48 da familia PB113 e 18 da familia PB111, propiciando intensidade de selecao de 6,1% e ganho genetico de 9,95%.

Evolução da vassoura-de-bruxa e avaliação da resistência em progênies de cupuaçuzeiro

Com o objetivo de conhecer a evolucao da doenca vassoura-de-bruxa, a taxa de segregacao e estimar parâmetros geneticos, foi conduzido um experimento com 21 progenies de irmaos completos de cupuacuzeiro, instalado em Belem, Para. As progenies foram obtidas pelo cruzamento controlado de clones resistentes com clones resistentes, clones resistentes com clones suscetiveis e, clones suscetiveis com clones suscetiveis. Foram avaliadas tambem tres progenies de meios-irmaos como testemunhas. Os experimentos foram avaliados ao nivel de individuos, e as analises foram conduzidas via metodologia de modelos lineares mistos (procedimento REMl/BlUP), como delineamento em blocos incompletos desbalanceados, com tratamentos comuns entre dois experimentos. As variaveis avaliadas foram: percentagem de plantas resistentes ao ataque da doenca no ramo, inflorescencia, fruto imaturo e maduro, no periodo de 2002 a 2007. Os resultados mostraram que a emissao de vassoura vegetativa e especialmente importante entre julho e setembro. A evolucao da doenca evidencia que as podas fitossanitarias devem ser realizadas no final da safra, nos meses de maio/junho, e repassadas em setembro/outubro. A populacao estudada oferece excelente possibilidade de selecao e ganho genetico, respaldada pelos elevados indices de variabilidade genetica e herdabilidade dos caracteres de resistencia. As progenies segregaram tanto para os sintomas de vassoura nos ramos, nas inflorescencias, como nos frutos imaturos e maduros. Para o controle integrado desta doenca, os resultados mostram a importância da associacao de materiais geneticos resistentes ou moderadamente resistentes a vassoura-de-bruxa com as podas fitossanitarias.

An index combining volume and Pilodyn penetration to study stability and adaptability of Eucalyptus multi-species hybrids in Rio Grande do Sul, Brazil

ABSTRACT This paper presents results from a study into the stability and adaptability of Eucalyptus multi-species hybrids in the state of Rio Grande do Sul, Brazil, using an index that includes volume growth and Pilodyn penetration. Clonal tests were established with 146 Eucalyptus clones from 34 different species and/or hybrids, in a randomised block design with 30 replications, and one plant per plot in four different sites. Diameter at breast height (dbh), tree total height (th), and Pilodyn penetration for indirect estimate of basic density were measured in trees at three years of age. An index (MAIweight) combining mean annual volume increment and Pilodyn penetration was calculated. In the analysis of MAIweight for each site, the best clones were from pure species (E. urophylla, E. grandis and E. saligna). In contrast, the evaluation of adaptability and stability between the four environments simultaneously showed that three-way cross and single cross hybrids ranked more highly: E. urophylla × (E. camaldulensis × E. grandis), E. grandis × (E. urophylla × E. grandis) and E. grandis × E. urophylla. This study demonstrates the importance of heterosis (hybrid vigour) to improving adaptability and stability. Genetic complementarity from crosses between different species was the principal process that produced the observed heterosis. While the pure species performed well in specific environments, the hybrids presented better broad adaptation to a range of environments. Breeding efforts should therefore account for these features when planning crosses and choosing sites for establishing trials.

Best linear unbiased prediction for genetic evaluation in reciprocal recurrent selection with popcorn populations

SUMMARY The objective of the present study was to present the theory and application of best linear unbiased prediction (BLUP) in reciprocal recurrent selection (RRS). Seven progeny tests from two RRS programmes with popcorn (Zea mays L. ssp. mays [syn. Zea mays L. ssp. everta (Sturtev.) Zhuk.]) populations were conducted and analysed for expansion volume and grain yield. The interpopulation half- and full-sib family models were fitted using ASReml software. Half-sib selection is equivalent to selection for the general combining ability (GCA) of the common parents. With inbred full-sib progeny and BLUP analysis, it is possible to predict the general and specific combining ability effects. The standard error of prediction of the progeny effect was lower than the standard deviation of the best linear unbiased estimation (BLUE) estimate. For half- and full-sib RRS, the BLUE and BLUP provided highly correlated estimates of progeny genotypic values. The coincidence between selected parents ranged from 64 to 95%. With inbred full-sib progeny, the correlations between the BLUE of progeny genotypic values and the BLUP of GCA effects were lower. Consequently, the coincidence between selected parents was lower, ranging from 0 to 57%. The percentage of common selected inbred progeny based on the BLUE and BLUP of the progeny genotypic value ranged from 57 to 100%.

A note on transgenerational epigenetics affecting egg quality traits in meat-type quail

ABSTRACT 1. The aim of the following experiment was to estimate transgenerational epigenetic variance for egg quality traits using genealogical and phenotypic information in meat-type quail. Measured traits included egg length (EL) and width (EWD), albumen weight (AW), shell weight (SW), yolk weight (YW) and egg weight (EW). 2. A total of 391 birds were evaluated for egg quality by collecting a sample of one egg per bird, during three consecutive days, starting on the 14th d of production. Analyses were performed using mixed models including the random epigenetic effect. Variance components were estimated by the restricted maximum likelihood method. A grid-search for values for the auto-recursive parameter (λ) was used in the variance components estimation. This parameter is directly related to the reset (v) and epigenetic transmissibility (1 − v) coefficients. 3. The epigenetic effect was not significant for any of the egg quality traits evaluated. Direct heritability estimates for egg quality traits ranged in magnitude from 0.06 to 0.33, whereby the higher estimates were found for AW and SW. Epigenetic heritability estimates were low and close to zero (ranging from 0.00 to 0.07) for all evaluated traits. 4. The current breeding strategies accounting for additive genetic effect seem to be suitable for egg quality traits in meat-type quail.