José A. G. da Silva

Dissimilaridade genética entre genótipos de aveia

Dezoito genotipos de aveia foram testados quanto a dissimilaridade genetica, com e sem o controle de molestias da parte aerea. As variaveis avaliadas foram rendimento de graos desaristados, peso de mil graos, peso do hectolitro, estatura de planta e dias da emergencia a floracao. Foram empregados analises por variaveis canonicas e tecnicas de agrupamento por meio dos metodos de otimizacao de Tocher e o metodo hierarquico do vizinho mais proximo, tendo como medida de dissimilaridade a distância generalizada de Mahalanobis. Pelos resultados, constatou-se significativa dissimilaridade genetica entre os genotipos, indicando a existencia de variabilidade para os caracteres avaliados. O metodo de Tocher e o metodo do vizinho mais proximo permitiram a separacao dos genotipos em grupos distintos, possibilitando a identificacao de futuros genitores que possam ser utilizados em cruzamentos artificiais que produzam progenies com maior heterose. Os caracteres que mais contribuiram para a dissimilaridade genetica foram o peso do hectolitro e a estatura de planta.

Efeito da densidade de semeadura e potencial de afilhamento sobre a adaptabilidade e estabilidade em trigo

The objectives of this work were to determine the grain yield adaptability and stability of ten wheat genotypes (Triticum aestivum L.), contrasting for the character tillering potential, conducted in different seeding densities. The experiments were conducted in the years 2005, 2006 and 2007 in Capao do Leao -RS and in Pato Branco-PR and Ijui-RS in the year 2007. A split-plot design was used considering the genotype as the plot and seeding density as the sub-plot. The seeding densities used were 50, 200, 350, 500 and 650 viable seeds m-2. The analyses of adaptability and stability were performed using the method proposed by Eberhart and Russell. The changes in seeding density and location intensely influenced the adaptability and stability parameters for grain yield. Genotypes adapted to various seeding densities were found (FUNDACEP 29 - except for 650 seeds m-2), as well as those with specific adaptability and a predictable performance only in favorable (CD 114) and unfavorable (CD 108) environments, indicating the need of an adequate fitting of seeding density to the performance predictability for grain yield in wheat.

SELEÇÃO INDIRETA EM AVEIA PARA O INCREMENTO NO RENDIMENTO DE GRÃOS

Different traits of economic importance for oat are correlated to each other in magnitude and varied sense. Such fact implies that the selection on a character can provide changes in the other, whose result can be or not interesting. Thus, the quantification of direct and indirect selection effects of one or several traits on others are of fundamental importance to guide improvement programs, representing the objective of this paper. 58 oat genotypes were evaluated, in Pelotas, RS, Brazil, in random block design with three replicates, on which phenotypic evaluations were conducted. These data were used to determine the simple correlation coefficients among variables. Starting from these coefficients, the path analysis procedure was applied on grain yield trait. In agreement with the obtained results, no analyzed variable presented direct effect on the grain yield similar to the phenotypic correlations coefficient, showing the existence of another traits influencing both in the magnitude and in the sense of the correlation, preventinng isolated selection on grain yield. Panicle weight showed the highest positive correlation with grain yield. However, stature and head date showed lower correlation coefficients, what makes difficult the indirect selection for grain yields. Grain number and grain weight, although positive and contributing to determine panicle weight, showed intermediary correlation with grain yield. Thus, to consider the effects of panicle weight, grain number and grain weight seems to be the best strategy for indirect selection of grain yield in oat.

Estimativa de coeficientes de correlação e trilha em gerações segregantes de trigo hexaplóide

The knowledge of how the agronomical traits are correlated in segregating populations is of primary importance for plant breeders, specially when one considers indirect selection through a character easily measurable or with high heritability correlated to the trait of interest with lower heritability. Agronomical traits in F2 and F3 generations of four wheat crosses, were evaluated on 2004 agricultural year in the Centro Agropecuario da Palma, of the Centro de Genomica e Fitomelhoramento - FAEM/UFPel, located in Capao do Leao country in Rio Grande do Sul State. The present work had the objectives to estimate for evaluated traits: a) genotypic, phenotypic and environmental correlation coefficients between the traits; and b) path coefficients for grain yield. For all populations, the single correlations indicated that the selection of higher yielding plants can be performed by indirect selection for number of fertile tillers per plant. The path analysis showed that it was possible to identify the indirect effect of the trait number of fertile tillers the as cause of the correlation between other traits (ear length x grain yield, spikelet number per ear x grain yield and number of ear grain x grain yield). Thus suggesting that the number of fertile tillers is the major trait to select for in order to obtain gains on grain yield.

Caráter stay-green e produtividade de grãos em trigo

ABSTRACTSTAY-GREEN TRAIT AND WHEAT GRAIN YIELD The stay-green trait is one of the factors that can aid the breeder in obtaining higher yieldingplants due to a delay in leaf senescence, favouring grain filling. The objective of this study was to evaluatethe performance of different wheat lines with and without the stay-green trait and investigate if longergreen period; foster an increment of grain yield. The field experiment was conducted in randomizedcomplete block design with three replications in two crop years. Genetically superior lines facilitate thebenefits of the stay-green trait for grain yield. The stay-green trait promotes yield stability under differentenvironments.Key words: Triticum aestivum L., green permanence, plant breeding.( 1 ) Recebido para publicacao em 5 de dezembro de 2006 e aceito em 5 de julho de 2007.( 2 ) Departamento de Estudos Agrarios - Agronomia/Universidade Regional do Noroeste do Estado do Rio Grande do Sul (Unijui),98700-000 Ijui (RS). E-mail: jose.gonzales@unijui.edu.br(

Variabilidade genética na busca de eficiência à produção de sementes e biomassa de capim Sudão

The objective of the study was to investigate the genetic variability of characters linked to inflorescence in populations of Sudan grass and the contribution of these variables in defining the most effective trait selection for seed yield. In addition, to provide subsidies to indicate that the selection pressure on the components of panicle to increase seed production does not compromise the character of forage interest. The experiments were conducted in the years 2009 and 2010 in the selection of plants for the characters tillering, biomass production and making up the inflorescence of the species. It was verified that there is genetic variability among populations of Sudan grass, especially in the mass character of panicle, number of grains in panicle and grain weight, variables of greatest contribution on the morphological differences observed in the inflorescence. Correlations were obtained for the effective mass of panicle and number of grains in panicle and increase in grain weight of panicle. The selection pressure on these characters does not bring harm on biomass and tillering.

Expressão do fenótipo em populações segregantes de aveia conduzidas em diferentes ambientes

Selection on the phenotype basis can be affected by environmental factors; forcing the plant-breeder to isolate genetic and environmental factors. The objective of this work was to evaluate the yield components of oat segregant populations subjected to different methods. Eight populations were planted in random block design with two replicates, according to three different models: spaced plant, full line and hill. Panicles with weight higher than mean plus one standard deviation were selected and measured for grain weight and grain number per panicle. Results showed a significant interaction between populations and environmental factors. Heritability was high, excepted for grain number/panicle on the full line models. Panicle weight can be an efficient trait to select genotypes in order to order increase grain yield.

Enraizamento de estacas de Chamaecyparis lawsoniana Parl. em cinco substratos com uso de ácido indolbutírico

To determine the best medium available in Pelotas, RS, for rooting of Chamaecyparis lawsoniana Parl. cuttings, the media fine vermiculite, carbonized rice hull, sand, carbonized rice hull + fine vermiculite and sand + fine vermiculite (1:1 v/v) were used. This experiment was carried out in a glass greenhouse with intermitent mist at the Plant Science Department of Faculdade de Agronomia Eliseu Maciel/Universidade Federal de Pelotas, from May to September 1997. Apical cuttings 15cm long were treated with indolbutyric acid (IBA) at 10.000ppm. The following evaluations were made: number of roots per cutting, weight of root dry matter, length of the longest root per cutting, and rooted cutting percentage. The results show that the vermiculite medium, with the IBA concentration utilized, is the most suitable for the rooting of C. lawsoniana cuttings, with 99% of rooting, greater number of roots per cutting (15), greater length of roots (12cm) and greater weight of root dry matter (0.04g).

Early generation selection strategy for yield and yield components in white oat

Several studies have searched for higher efficiency on plant selection in generations bearing high frequency of heterozygotes. This work aims to compare the response of direct selection for grain yield, indirect selection through average grain weight and combined selection for higher yield potential and average grain weight of oat plants (Avena sativa L.), using the honeycomb breeding method. These strategies were applied in the growing seasons of 2001 and 2002 in F3 and F4 populations, respectively, in the crosses UPF 18 CTC 5, OR 2 ´ UPF 7 and OR 2 ´ UPF 18. The ten best genetic combinations obtained for each cross and selection strategy were evaluated in greenhouse yield trials. Selection of plants with higher yield and average grain weight might be performed on early generations with high levels of heterozygosis. The direct selection for grain yield and indirect selection for average grain weight enabled to increase the average of characters under selection. However, genotypes obtained through direct selection presented lower average grain weight and those obtained through the indirect selection presented lower yield potential. Selection strategies must be run simultaneously to combine in only one genotype high yield potential and large grain weight, enabling maximum genetic gain for both characters.

Métodos de semeadura na condução de populações segregantes de aveia e suas interações com o ambiente de seleção

Phenotype-based selection can be influenced by environmental factors. Plants breeders need to use selection methods to separate genetic from environmental effects. The goal of this study was to test the efficacy of indirect selection to increase oat (Avena sativa L.) grain yield under different sowing systems. Eight oat segregant populations were selected for panicle weight under three different sowing methods (hill, spaced plant, full line), during 2000 and 2001 growing seasons, The development of superior genotypes required evaluation in distinct years mainly to minimize environment effects. Sowing systems seemed to have extreme importance to selection. Sowing oat in hill provided reduced environmental contribution in the expression of panicle weight.