ABSTRACT The objective of this study was to evaluate 94 Paspalum notatum genotypes over two growing seasons to estimate genetic dissimilarity through agronomic traits and the distance between genotypes. This information is used to create an ideotype from the best averages obtained for the set of characteristics evaluated. Seven apomitic, three sexual, and 81 hybrid genotypes were compared with native genotypes “André da Rocha”, “Bagual”, and cultivar “Pensacola” as controls. There is genetic variability in P. notatum for the studied characteristics, and distinct genotypes with superior characteristics can be used in new combinations between apomictic and sexual plants to obtain hybrids. The characters with the greatest relative contribution to the dissimilarity between the genotypes were tiller density, stem dry mass, and leaf dry mass yield. Thus, these characteristics are suitable criteria to infer genetic distance studies in P. notatum . The selection index based on the ideotype is an auxiliary tool in the breeding process. The ideotype must be based on characteristics of interest according to the objective of the breeding program, as well as on the breeder’s prior knowledge in relation to culture.

RESUMO O gênero Paspalum compõe as pastagens naturais das regiões tropicais e subtropicais da América com várias espécies de reconhecido potencial forrageiro. O objetivo deste estudo foi avaliar a influência de diferentes níveis de fertilização nitrogenada sobre os caracteres agronômicos e na eficiência de utilização de nitrogênio por genótipos superiores de P. notatum Flügge. Foram avaliados quatro níveis de fertilização nitrogenada (0, 60, 180 e 360 kg N ha-1) e nove genótipos, seis provenientes do United States Departament of Agriculture (USDA) (30N, 36N, 48N, 70N, 83N e 95N), coletados na América do Sul, dois genótipos nativos do Rio Grande do Sul, Brasil (André da Rocha e Bagual) e a cv. Pensacola. O delineamento experimental utilizado foi o de blocos casualizados em esquema fatorial 4 x 9, com quatro repetições de campo. A partir da variabilidade de respostas encontradas para os caracteres agronômicos são indicados a prosseguir no programa de melhoramento genético os genótipos 48N, André da Rocha e Bagual por atingirem as máximas eficiências produtivas de acordo com as doses de N testadas.O genótipo 36N que obteve a maior eficiência de utilização de nitrogênio, demonstrando-se biologicamente viável com a menor dose de N, equivalente a 60 kg de N ha-1.

SUMMARY The Paspalum genus forms the natural pastures of the tropical and subtropical regions of America and includes several species of recognized forage potential. The aim of this study was to evaluate the influence of different levels of nitrogen fertilization on the agronomic traits and nitrogen use efficiency in superior genotypes of Paspalum notatum Flügge. Four nitrogen fertilization levels (0, 60, 180 and 360 kg N ha-1) and nine genotypes were evaluated, six from the United States Department of Agriculture (USDA) (30N, 36N, 48N, 70N, 83N and 95N), collected in South America, two native genotypes of Rio Grande do Sul, Brazil (André da Rocha and Bagual) and cv. Pensacola. The experimental design was a randomized complete block in a 4 x 9 factorial, with four field replications. From the variability of the responses found for the agronomic traits, the genotypes 48N, André da Rocha and Bagual are indicated to continue in the breeding program because they reach the maximum productive efficiencies according to the doses of N tested. The genotype 36N obtained the highest efficiency of nitrogen utilization, being biologically viable with the lowest N dose, equivalent of 60 kg of N ha-1.

ABSTRACT This study aimed to estimate the genetic parameters, genetic correlations, genetic dissimilarity, and predicted gains with the selection of interspecific apomictic Paspalum plicatulum × Paspalum guenoarum hybrids in relation to seed yield traits. Nineteen genotypes that showed increased forage yield in previous studies were planted in a randomized complete block design with ten blocks. Traits evaluated in this study were: number of tillers/plant, number of reproductive tillers/plant, number of racemes/inflorescence, number of seeds/inflorescence, weight of a thousand seeds, and seed yield. Data were analyzed using a mixed model approach. The genotypes evaluated in our study showed improvement potential in relation to high heritability (H a 2 > 0.50 ), high precision (Acgen> 90%), and genetic dissimilarity (forming three groups) for seed yield traits. Seed yield showed high correlation to reproductive tillers that can be used as indirect selection tools for genetic improvement of seed yield.

ABSTRACT: For many decades, animal production in southern Brazil has been based on native forage grasses. Paspalum notatum Flügge (bahiagrass) is one of the most frequently used native grass in southern Brazil. The native germplasm of P. notatum is tetraploid and displays apomictic reproduction; hence, chromosome doubling of sexual diploid accessions is required to facilitate hybridization. The main goal of this study was to evaluate forage production and other agronomical evaluation of P. notatum intraspecific hybrids in order to obtain new varieties that could be registered and/or protected and launched as new cultivars in the future. Three tetraploid sexual genotypes were crossed with the ecotypes Bagual and André da Rocha. Biomass production (leaf, stem, and inflorescence fractions), plant growth habit, plant height, number of tillers, and frost damage were evaluated in the resulting hybrids. The general combining ability (GCA) and specific combining ability (SCA) were calculated for the six families generated. We evaluated 196 hybrids and the most productive yielded 42 % more total dry mass than the most productive parent (ecotype Bagual), and Bagual production was seven-fold higher than that of cultivar ‘Pensacola’. The highest GCA values were observed for Bagual and Q4205. No correlation was observed between leaf coloration and the frost effect or regrowth in the following winter. Similarly, no correlation between plant growth habit and dry mass production was observed. The reproduction mode of the most productive hybrids are currently being analyzed in larger plots to identify apomictic and sexual genotypes for future registration and protection.

ABSTRACT This study aimed to determine the variability and expression of the components of seed yield in twenty-three apomictic Paspalum plicatulum × Paspalum lepton hybrids and two male parent plants (P. lepton). We used a randomized block design with genotypes individually arranged into ten blocks. The variables were: number of total tillers/plant, number of vegetative tillers/plant, number of reproductive tillers/plant, percentage of reproductive tillers, number of racemes/inflorescence, number of seeds/inflorescence, weight of a thousand seeds, and seed yield. We assessed genetic variability using multivariate procedures: generalized Mahalanobis distance, Tocher's clustering optimization method, and quantification of the relative contribution of the variables. The quantification of variability, based on the components of seed yield of Paspalum plicatulum × Paspalum lepton hybrids, allows the formation of six groups of genotypes using Tocher's method, with high means for the characteristics studied. Weight of a thousand seeds and number of seeds/inflorescence were the traits that most contributed to the genetic dissimilarity. Genetic crosses involving genotype 10E5052 from group VI and 10E4071 from group V could be undertaken to isolate high yielding segregants, since these genotypes have high seed yielding potential.

RESUMO O objetivo deste estudo foi avaliar a expressão de caracteres agronômicos e a tolerância ao frio de híbridos apomíticos de Paspalum plicatulum x P. guenoarum, bem como estimar suas correlações fenotípicas, em duas regiões edafoclimáticas distintas. O estudo foi conduzido em diferentes locais e anos de avaliação, em delineamento de blocos ao acaso, com três repetições. Foram avaliados quatro híbridos interespecíficos de Paspalum, dois genótipos de P. guenoarum e a cv. Aruana (Panicum maximum), utilizada como testemunha. Os híbridos H12, H13, H20 e H22 apresentaram superioridade para os caracteres agronômicos avaliados e tolerância ao frio, em relação às cvs. Rojas e Aruana e ao ecótipo Azulão, e são indicados para novas etapas de avaliação, como estimativas da produção de sementes e estudos de DHE e VCU, visando o lançamento como novas cultivares. As estimativas de correlações fenotípicas são importantes ferramentas para a seleção de progênies, com destaque para o caráter MSF que apresentou alta correlação positiva com os caracteres MST, DPP, rebrote e altura, indicando ser desnecessária a realização de separação morfológica, economizando tempo e mão de obra em um programa de melhoramento de forrageiras.

ABSTRACT The aim of this study was to evaluate the expression of agronomic characteristics and tolerance to cold in apomictic Paspalum plicatulum x P. guenoarum hybrids, and estimate their phenotypic correlations in two different regions of soil and climate. The study was conducted at different locations and evaluated in different years, in a randomised block design with three replications. Four interspecific hybrids of Paspalum and two genotypes of P. guenoarum were evaluated, with the Aruana cultivar (Panicum maximum) used as a control. The H12, H13, H20 and H22 hybrids proved to be superior in tolerance for cold and the agronomic traits evaluated relative to the Rojas and Aruana cultivars and the Azulão ecotype, and are suitable for new stages of assessment, such as estimates of seed production and studies of DHS and VCU, with a view to their release as new cultivars. Estimates of phenotypic correlations are important tools in progeny selection, especially the characteristic of LDM, which showed a high positive correlation with the characteristics TDM, PDP, regrowth and height, demonstrating that carrying out morphological separation is unnecessary, saving time and labour in a forage breeding program.

RESUMO O objetivo do trabalho foi fornecer subsídios para obtenção de ganho genético em espécies apomíticas do gênero Paspalum pela identificação de caracteres que evidenciem simultaneamente alta correlação e herdabilidade. Assim, dimensionar o quanto da variação fenotípica é devido a efeitos genéticos e ambientais e o grau de associação existente entre a produção da matéria seca de folha como outros caracteres de interesse forrageiro de mais fácil seleção e aferição, proporcionará agilidade e economia no processo de seleção de plantas forrageiras. O experimento foi conduzido nos anos de 2009/10 e 2010/11 nos municípios de Eldorado do Sul e Augusto Pestana, RS, Brasil, em um delineamento experimental de blocos casualizados com três repetições. Nos acessos apomíticos do gênero Paspalum o aumento da pressão de seleção direta sobre a matéria seca total e de folhas é fortalecida pela maior contribuição dos efeitos genéticos do que ambientais sobre a composição da variância fenotípica. O ganho genético na produção de folhas se mostra eficiente via seleção indireta pela matéria seca total, caráter de elevada herdabilidade e de mais fácil seleção e aferição.

ABSTRACT The objective of this work was to provide means to obtain genetic gain in apomictic species of the genus Paspalum by identifying traits that simultaneously show high correlation and heritability. Thus, to determine the amount of phenotypic variation due to genetic and environmental effects and the degree of association between leaf dry matter production and other traits of forage interest that are easy to select and measure will bring agility and economy in the selection of forage species. The experiment was conducted in the years 2009/10 and 2010/11 in the municipalities of Eldorado do Sul and Augusto Pestana, RS, Brazil, in a randomized complete block design with three replicates. The increase in the direct selection pressure on total and leaf dry matter of apomictic accesses of the genus Paspalum is enhanced by a greater contribution of genetic effects than environmental effects on the composition of the phenotypic variance. Efficient genetic gain in leaf production is achieved by indirect selection of total dry matter, which is a trait of high heritability and easy to select and measure.

ABSTRACT The objective of this study was to evaluate the influence of photoperiod on the forage yield by ecotypes and intraspecific hybrids of P. notatum. Tetraploid ecotypes from the United States Department of Agriculture and the National University of the Northeast in Argentina, in addition to six intraspecific hybrids, totaling 19 ecotypes, were assessed. The materials evaluated were subjected to an extended photoperiod (14 h of light) and natural photoperiod from July 2011 to October 2012. The experimental design was a completely randomized factorial scheme of 19 × 2 (ecotypes × photoperiod) consisting of five replicates. The materials were influenced differentially by the variation in photoperiod, with one group showing high sensitivity, whereas another, smaller group, was insensitive to this factor. The use of materials with differentiated responses to photoperiod in different climatic regions can be an important tool to increase forage yield of Paspalum notatum.

RESUMO: O objetivo deste estudo foi avaliar a variabilidade de híbridos interespecíficos de Paspalum plicatulum x P. guenoarum por meio do desempenho agronômico e tolerância ao frio, bem como estimar as correlações fenotípicas de diferentes caracteres ligados à produção de forragem. Foram utilizados 20 híbridos, um acesso de P. guenoarum , um de P. plicatulum e a cultivar 'Pensacola' ( P. notatum ). As avaliações foram realizadas em plantas individuais, em delineamento completamente casualizado, com cinco repetições. Os genótipos de Paspalum apresentam variabilidade para massa seca total, massa seca de folhas e relação folha: colmo e na tolerância ao frio. É possível selecionar os híbridos 08Q01 e 08Q44 para novas etapas dentro de um programa de melhoramento de forrageiras. As estimativas de correlações fenotípicas podem auxiliar na seleção de genótipos com caracteres agronômicos superiores.

ABSTRACT: The goal of this study was to assess the variability of Paspalum plicatulum x P. guenoarum interspecific hybrids in terms of agronomic performance and their tolerance to cold conditions, as well as to estimate the correlation of different phenotypic characters associated with forage production. Twenty hybrids plants were used, besides one access P. guenoarum , one of P. plicatulum and the cultivar 'Pensacola' ( P. notatum ). Assessments were performed on individual plants, in a completely randomized design with five repetitions. Paspalum genotypes presented variability in total dry matter, leaf dry mass, leaf: stem ratio, and tolerance to cold. We suggest selection of the hybrids 08Q01 and 08Q44 for new stages within a forage improvement program. Estimates of phenotypic correlation may aid in the selection of genotypes with better agronomic traits.

The objective of this study was to analyze the adaptability and the stability in apomictic genotypes of the genus Paspalumacross the main characters of forage interest evaluated in different years and locations. The experiment was conducted in the years 2010 and 2011 in the municipalities of Eldorado do Sul and Augusto Pestana, RS, Brazil, in a randomized complete block design with three replications. Analyses of adaptability and stability were calculated by the Traditional and the Eberhart and Russel method. The genotypes of P. guenoarumBaio anda Azulão shows high biomass production but adapted to favorable environments and reduced stability. The genotypes of P. lepton28C show the total dry mass specific adaptability to unfavorable environment and in the dry leaf adaptability with stability

O objetivo deste trabalho foi determinar a variabilidade genética e a expressão de caracteres de interesse forrageiro em espécies de Paspalum. Os experimentos foram conduzidos em diferentes locais e anos de cultivo, em delineamento de blocos ao acaso, com três repetições. Foram avaliados cinco acessos de P. nicorae e dois de P. guenoarum, além da cultivar Pensacola (P. notatum), utilizada como testemunha. Foram quantificados os seguintes caracteres: relação folha/colmo, índice de colheita e massa de matéria seca total, de folhas e de colmo. Tanto os efeitos principais (genótipos, anos e locais de cultivo) quanto a interação entre os fatores tiveram influência significativa sobre os caracteres avaliados. Os acessos avaliados apresentam variabilidade genética em caracteres de interesse forrageiro, bem como desempenho variável de acordo com o local e o ano de cultivo. A produção de matéria seca total e de folhas são os caracteres que mais contribuem para a detecção da variabilidade genética observada, independentemente do ano de avaliação.

The objective of this work was to determine the genetic variability and the expression of traits of interest for forage production in species of Paspalum. The experiments were carried out in different locations and crop years in randomized block design with three replicates. Five accessions of P. nicorae and two of P. guenoarum were evaluated, besides the cultivar Pensacola (P. notatum), used as a control. The following traits were determined: leaf/stalk ratio; harvest index; and total, leaf, and stalk dray matter. Both main effects (genotype, years, and locations) and the interactions among factors had significant influence on the evaluated traits. The evaluated accessions showed genetic variability in traits of interest for forage production, and their performance varied according to the location and year of cultivation. Total and leaf dry matter production are the traits that most contribute to the detection of the observed genetic variability, regardless of the year of evaluation.

Realizou-se neste estudo uma avaliação inicial em diversas linhagens de aveia-branca (Avena sativa, L.), com o intuito de verificar o desempenho agronômico e identificar os genótipos promissores para o lançamento de cultivares para produção de forragem. Os experimentos foram conduzidos em duas regiões fisiográficas do estado do Rio Grande do Sul, Depressão Central e Campanha Gaúcha, nos anos de 2008 e 2009. Foram implementados em blocos casualizados com quatro repetições. Cada parcela foi constituída por uma linha de 2 m de comprimento, espaçadas a 40 cm entre si, considerando parcela útil o metro linear central, cortadas a uma altura de 10 cm. Foram avaliadas 21 linhagens de aveia-branca mais a testemunha (IPR126). No primeiro ano, também foram avaliadas duas linhagens de triticale, as quais apresentaram baixo potencial forrageiro e foram excluídas dos experimentos no segundo ano. Na avaliação do potencial produtivo das linhagens de aveia-branca, não houve diferenças ocasionadas pela interação dos fatores local, ano e linhagem. No primeiro ano, os valores médios de produção na Depressão Central e Campanha Gaúcha foram de 82,3 e 76,3 g por metro linear de matéria seca total, respectivamente. Na avaliação do segundo ano, as médias de produção para esta espécie na Depressão Central e na Campanha Gaúcha foram, respectivamente, 80,0 e 119,8 g m-1 de matéria seca total. As linhagens de aveia-branca, em sua maioria, apresentam bons resultados e são promissoras para o programa de melhoramento genético dessa espécie.

The objective of this study was to proceed with an initial evaluation of various strains of white oats (Avena sativa, L.), with the objective of characterizing the genetic diversity and the agronomic performance, identifying the promising genotypes for the release of cultivars, with the purpose of forage production. The experiments were conducted in two geographical regions of the State of Rio Grande do Sul, Depressão Central and in the Campanha Gaúcha, Brazil, in the years 2008 and 2009, in a randomized block design with four replications. Each plot consisted of a 2-m line, with lines spaced at 40 cm. The central linear meter was considered as useful plot, cut to a height of 10 cm. Twenty-one oat lines were evaluated, plus the control (IPR126). In the first year, two strains of triticale were also studied, and had a low potential for forage and were excluded from the experiments in the second year. The productive potential of oat strains did not differ for the interaction of location, year or lineage, with the first year of average production in the Depressão Central and Campanha Gaúcha, of, 82 3 and 76.3 grams per meter of total dry matter (TDM), respectively. At the second year evaluation, the means of production for this species in the Depressão Central and Campanha Gaúcha were 80.0 and 119.8 g m-1 TDM. Most strains of oats present good results and are promising for the breeding program of this species.

O objetivo neste trabalho foi selecionar genótipos mais produtivos e persistentes de trevo-branco (Trifolium repens L.) por meio da avaliação agronômica de suas progênies. Foi avaliada a produção de matéria seca (MS) de 22 progênies comparadas à população UFRGS-2004-2 e à cultivar Jacuí de trevo-branco consorciadas com azevém (Lolium multiflorum Lam.) durante os anos de 2008 e 2009. A média de produção de MS de trevo-branco durante os dois anos foi de 3.671 e 2.107 kg/ha em Eldorado do Sul e Bagé, respectivamente. Em Eldorado do Sul e Bagé, a cultivar Jacuí com mais 13 progênies formaram os grupos com maior produção. Sete progênies ficaram no grupo "a" em ambos os locais, enquanto somente a população UFRGS e uma progênie apresentaram menores produções nos dois locais, havendo interação genótipo × ambiente. As progênies 2, 6 e 7 oriundas de Bagé e 22 (Etiópia), 23 (Portugal), 24 (Estados Unidos) e 30 (Irlanda) podem ser utilizadas na formação de uma cultivar sintética mais produtiva e persistente as condições do verão.

The aim of this work was to select higher yielding and persistent genotypes, evaluating their progenies agronomically. The DM yield of 22 progenies compared with the population of UFRGS-2004-2 and with the Jacuí cultivar of white clover mixed with ryegrass (Lolium multiflorum Lam.), during the years 2008 and 2009 was evaluated. The average DM yield of white clover during the two years was 3671 and 2107 kg/ha, in Eldorado do Sul and Bagé, respectively. In Eldorado do Sul and Bagé the Jacuí cultivar with thirteen more progenies formed groups with higher production. Seven progenies were in the group "a" in both places, whereas only the population of UFRGS and one progeny had lower production in both sites, with genotype × environment interaction. Progenies 2, 6 and 7 from Bage and 22 (Ethiopia), 23 (Portugal), 24 (United States) and 30 (Ireland), can be utilized in the creation of a more productive and synthetic cultivar, in addition to being more resistant to summer conditions.

Este estudo foi realizado para avaliar uma coleção de 53 acessos de Paspalum nicorae, estabelecidos em duas regiões fisiograficamente distintas durante dois anos, buscando caracterizar a produção e qualidade de forragem dos acessos para etapas subsequentes em programa de melhoramento de plantas forrageiras. Os acessos foram estabelecidos em linhas, num delineamento de blocos casualizados com três repetições, e as avaliações foram realizadas de outubro de 2007 a fevereiro de 2009 por meio de cortes. Houve variação da produção de forragem entre os acessos ao longo do tempo e entre os locais. A maioria dos acessos de P. nicorae apresentou elevado rendimento de forragem em comparação à testemunha (P. notatum cv. Pensacola) e alguns acessos apresentaram desempenho bem expressivo. Os percentuais de proteína bruta obtidos nos acessos da coleção foram semelhantes aos encontrados na testemunha. Os acessos 28B e 26A de P. nicorae são indicados para etapas subsequentes de um programa de melhoramento de plantas forrageiras.

This study was carried out to evaluate a collection of 53 accessions of Paspalum nicorae, introduced in two physiographically distinct regions over two years, with the objective of characterizing production and quality of forage of access for subsequent phases of a forage plant breeding program. The accessions were established in lines in randomized block design with three replications and the evaluations were performed from October 2007 to February 2009 by using cuts. There was variation of forage production among access over time and among sites. The majority of the accessions of P. nicorae presented high forage yield when compared with the control (P. notatum cv. Pensacola) and some accessions presented very expressive performances. The percentages of crude protein obtained from accessions in the collection were similar to the ones found in the control access. The accessions 28B and 26A of P. nicorae are indicated for subsequent stages in a program of forage plant breeding.