Potential of hybrids among elite clones of eucalypt by microsatellite markers

O objetivo deste trabalho foi avaliar o potencial dos marcadores microssatélites em predizer o comportamento dos híbridos entre clones-elite de eucalipto da empresa Aracruz Celulose. Foram utilizados 21 clones-elite, cruzados conforme o esquema de dialelo balanceado. Os 137 híbridos obtidos, além dos 21 pais e 11 híbridos repetidos, foram avaliados em três locais: Aracruz, São Mateus e Caravelas, em delineamento de blocos incompletos 13x13 com 40 repetições. As parcelas foram constituídas de uma planta, espaçadas 3x3 m. Os caracteres circunferência à altura do peito (CAP) e densidade básica da madeira foram avaliados aos dois anos de idade. Os dados foram submetidos à análise dialélica e, posteriormente, foi obtida a correlação entre a divergência genética dos genitores, obtida por meio dos marcadores microssatélites, e as estimativas dos parâmetros do dialelo. A divergência genética apresentou coeficientes de correlação significativos apenas com a capacidade específica de combinação para CAP e com a média dos híbridos para CAP. A predição por meio de marcadores microssatélites possui baixa precisão para poder ser utilizada em substituição aos cruzamentos dialélicos.The objective of this work was to evaluate the potential of microsatellite markers to predict the performance of hybrids among elite clones of eucalypt from Aracruz Celulose. Twenty one elite clones were crossed in a full-diallel mating scheme. One hundred and thirty seven hybrids, 21 parents and 11 repeated hybrids were evaluated in three sites: Aracruz, São Mateus and Caravelas, in an experimental design of incomplete blocks 13x13 with 40 replicates, comprising single plant plot and spaced 3x3 m. The characters evaluated were the circumference at breast height (CBH) and the wood basic density, two years after the planting. Means were submitted to diallel analysis and, later, the correlation between the genetic divergence of parents by microsatellite markers and the estimative of diallel parameters were obtained. The genetic divergence was correlated with the specific combining ability to CBH height and with the means of hybrids to the same character. The other coefficients of correlation with the genetic divergence were not significantly different from zero. The prediction by microsatellite markers is of little accuracy to be utilized in place of diallel estimates

Potencial de híbridos simples de milho para extração de linhagens Potential of maize single hybrids to generate inbred lines

A utilização de híbridos simples comerciais de milho é uma das opções de populações para a extração de linhagens, porque são adaptados e provavelmente concentram alta freqüência de alelos favoráveis já fixados. Mesmo nos locos que estão segregando, a freqüência de alelos favoráveis é 0,5. Assim, a identificação de populações promissoras, derivadas de híbridos simples superiores, é uma boa estratégia para aumentar a eficiência dos programas de melhoramento. As populações derivadas dos híbridos simples comerciais AG9012 e C333 foram avaliadas com o objetivo de verificar o potencial dessas para extração de linhagens superiores, por meio das estimativas de parâmetros genéticos e fenotípicos, da estimativa de m+a e a metodologia proposta por Jinks & Pooni (1976). Foram avaliadas 169 famílias S1 de cada população, durante a safra agrícola de 1999/2000, na área experimental do Departamento de Biologia da UFLA, em Lavras - MG, em látice simples 13x13, sendo as parcelas constituídas por uma linha de 3 m. As características analisadas foram incidência de Phaeosphaeria maydis em duas épocas, altura de plantas, altura de espigas e produtividade de espigas despalhadas. Foi constatado que há possibilidade de se obterem linhagens com bom desempenho per se, sendo a população derivada do C333 a mais promissora, por associar resistência a Phaeosphaeria maydis e possuir média mais alta e maior probabilidade de obtenção de linhagens superiores. A metodologia proposta por Jinks & Pooni (1976) mostrou-se mais informativa do que a estimativa de m+a para a escolha de populações, mas, quando possível, as duas podem ser utilizadas simultaneamente para auxiliar na decisão dos melhoristas.<br>Populations derived from commercial single hybrids are one of the breeder options for inbred line extraction because of their adaptation and probable high frequency of loci with fixed favorable alleles. Even the segregating loci carry favorable alleles at a frequency of 0.5. Therefore, identification of promising single hybrid populations for inbred line extraction is strategic to increase the efficiency of breeding programs. The populations derived from the two commercial single hybrids AG9012 and C333 were assessed to estimate their capacity to inbred line extraction using the genetic and phenotypic parameters estimate, the m+a estimate and Jinks & Pooni (1976) methodology. Two sets of 169 S1 families derived from each hybrid population were assessed during the 1999/2000 growing season in the experimental area of the Biology Department at UFLA in Lavras, MG. The families were assessed in two simple 13 x 13 lattices in 3 m single row plots. The assessed traits were: a) incidence of Phaeosphaeria maydis in two sowing periods; b) plant height; c) ear height; and, d) de-hulled ear yield. It was detected that inbred lines with good "per se" performance can be obtained. The C333 hybrid derived population was the most promising for breeding purposes due to its resistance to Phaeosphaeria maydis associated with a higher mean and greater potential to generate superior inbred lines. The Jinks & Pooni (1976) methodology gave more informations to help the population choice than the m+a estimate. However, when it's possible, both can be used together to help the plant breeders to make a choice

EVALUATION OF CORN HALF SIB FAMILIES AT DIFFERENT INTER ROW SPACING

In this work, 196 half-sib corn families from CMS 39 population wereevaluated at different inter row spacing with the purpose of verifying their genetic potentialin distinct sowing arrangements. The experiments were conducted in 2001/2002, at theexperimental area of UFLA‘s Biology Department, located in Lavras, Minas Gerais,Brazil. Two distinct and contiguous experiments were conducted in a 14 x 14 simplelattice design with two replications and sown in a non-tillage system. On the firstexperiment, plots were represented by single 4 m long , 50 cm spaced rows. The spacingbetween plants within rows was 40.0 cm. On the second experiment, the inter row spacing was 90.0 cm and inter plant spacing was 22.2 cm, keeping the same density of 50.000plants ha-1. The evaluated traits were husked ear weight, plant/ear height and prolificacy.Interaction row spacing x genotype was significant, indicating it is more efficient toconduct corn improvement programs at different inter row spacing for this population.The 50.0 cm inter row spacing provided the best ear weight yield and greatest prolificacy.Gains from selection for ear weight were similar at both spacings, but it is more interestingto carry out a breeding program at 50.0 cm inter row spacing, because this arrangementprovided the highest average for all the evaluated characters

Dialelo parcial entre clones de Eucalyptus camaldulensis e clones de E. urophylla, E. grandis e E. saligna Half-diallel between Eucalyptus camaldulensis clones and E. grandis E. urophylla, and E. saligna clones

O objetivo deste trabalho foi identificar combinações híbridas superiores nos cruzamentos entre clones-elite de Eucalyptus grandis, E. urophylla e E. saligna com clones-elite de E. camaldulensis da Aracruz Celulose S.A., por meio de cruzamentos dialélicos parciais. Para isso, as 44 combinações híbridas obtidas e mais quatro testemunhas foram plantadas de setembro a outubro de 2001, em três localidades: Aracruz, ES; São Mateus, ES; e Caravelas, BA, no delineamento de blocos casualizados com 40 repetições e uma planta por parcela. Dois anos após o plantio, foram avaliadas a circunferência à altura do peito (CAP) e a densidade básica da madeira (DEN). Os dados médios foram submetidos à análise dialélica segundo o método de Griffing (1956), adaptado por Geraldi e Miranda Filho (1988). Constatou-se que muitos híbridos foram promissores tanto para a obtenção de ganhos em CAP quanto para obter a densidade da madeira, pois associaram média e variância altas. A maior parte da variação entre os híbridos foi explicada pela capacidade geral de combinação, indicando a predominância de efeitos aditivos no controle dos caracteres.The objective of this research was to evaluate the hybrid potential between E. grandis, E. urophylla and E. saligna clones from Aracruz Celulose S. A. with E. camaldulensis clones. To do so, six elite clones were crossed with ten E. camaldulensis clones, in a half-diallel mating design. The resulting hybrid combinations as well as the four check clones were carried out from September to October 2001, in three sites, Aracruz and São Mateus, in the Espírito Santo State, and Caravelas, Bahia State, in a completely randomized block design with single plant plots and 40 replicates. Two years later, the circumference at breast height and the wood basic density were measured. The means were submitted to a diallel analysis, according to the Griffing (1956) method, adapted by Geraldi and Miranda Filho (1988). It was observed that the diallel crossings were promising for both the wood volume and wood quality gain. The general combining ability was responsible for most of the variations between the hybrids

Combining ability of elite clones of Eucalyptus grandis and Eucalyptus urophylla with Eucalyptus globulus

In Brazil, eucalyptus breeding programs for cellulose production has used two species, Eucalyptus grandis and Eucalyptus urophylla. Nevertheless, it would be useful to introgress alleles from other species to improve wood quality and volume. The objective of this research was to evaluate the hybrid potential of elite clones of E. grandis and E. urophylla from the Aracruz Celulose Company S. A. with Eucalyptus globulus clones. To do so, six elite clones were crossed with ten E. globulus clones in a half-diallel mating design. The resulting hybrid combinations as well as the four check clones were evaluated in randomized complete block experiments with single plant plots and 40 replicates from September to October 2001 at three Brazilian sites, Aracruz and São Mateus in the Espírito Santo state and Caravelas in Bahia State. Two years later the circumference at breast height (CBH) and the wood density (WD) were measured. The means were submitted to diallel analysis according to the Griffing method (1956), adapted by Geraldi and Miranda Filho (1988). Although the number of clones involved was small, the crossings of elite clones of E. grandis and E. urophylla with clones of E. globulus were promising, especially for wood quality gains