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The effects of defoliation frequency (21, 28, 35 and 42 days) and defoliation intensity (20, 30 and 40 cm above the ground) on green dry matter (GDM) yield, and chemical composition of Megathyrsus maximus cv. Tamani were evaluated under natural field conditions at the Roraima´s savannas. Defoliation regimes affect productivity and chemical composition of M. maximus cv. Tamani forage. The decrease in the pasture defoliation frequency and intensity improved the accumulation of forage, however it reduces the tissue concentrations of N, P, Ca, Mg and K. Irrespective of defoliation frequencies, the highest levels of N (25.31 g kg-1), P (2.11 g kg-1), Mg (2.78 g kg-1) and K (21.13 g kg-1) were recorded for the defoliation intensity at 40 cm above the ground, except for Ca (4.31 g kg-1), where the greatest concentration was obtained with defoliations at 30 cm above the ground. The use of defoliation frequency around 32 days and defoliation intensity of 28 cm above the ground can be considered adequate for the management of pastures of M. maximus cv. Tamani, in order to provides higher forage productivity and quality, regrowth vigor, larger efficiency of forage utilization, greater tissue renewal and canopy structure more favorable to grazing Made available in DSpace on 2021-10-18T19:00:40Z (GMT). No. of bitstreams: 1 PubVet-2021-Produtividade-e-composicao-quimica-da-forragem-de-Megathyrsus-maximus-cv.-Tamani-sob-regimes-de-desfolhacao.pdf: 404226 bytes, checksum: 2c10af0da8c33992d6c90beabb689c7f (MD5) Previous issue date: 2021

Made available in DSpace on 2022-08-22T19:24:10Z (GMT). No. of bitstreams: 1 RSD-2022-Agronomic-performance-and-chemical-composition-of-genotypes-and-cultivars-of-Megathyrsus-maximus-in-Roraimas-savannas-1.pdf: 109091 bytes, checksum: 1450c4c0f1861c4df1e00af41c9a3ff0 (MD5) Previous issue date: 2022

Artificial hybridization plays a fundamental role in plant breeding programs since it generates new genotypic combinations that can result in desirable phenotypes. Depending on the species and mode of reproduction, controlled crosses may be challenging, and contaminating individuals can be introduced accidentally. In this context, the identification of such contaminants is important to avoid compromising further selection cycles, as well as genetic and genomic studies. The main objective of this work was to propose an automated multivariate methodology for the detection and classification of putative contaminants, including apomictic clones (ACs), self-fertilized individuals, half-siblings (HSs), and full contaminants (FCs), in biparental polyploid progenies of tropical forage grasses. We established a pipeline to identify contaminants in genotyping-by-sequencing (GBS) data encoded as allele dosages of single nucleotide polymorphism (SNP) markers by integrating principal component analysis (PCA), genotypic analysis (GA) measures based on Mendelian segregation, and clustering analysis (CA). The combination of these methods allowed for the correct identification of all contaminants in all simulated progenies and the detection of putative contaminants in three real progenies of tropical forage grasses, providing an easy and promising methodology for the identification of contaminants in biparental progenies of tetraploid and hexaploid species. The proposed pipeline was made available through the polyCID Shiny app and can be easily coupled with traditional genetic approaches, such as linkage map construction, thereby increasing the efficiency of breeding programs. Made available in DSpace on 2021-12-07T14:00:42Z (GMT). No. of bitstreams: 1 SemiAutomatedSNP.pdf: 2844859 bytes, checksum: e7cb8fd79620358847aaa86717df754b (MD5) Previous issue date: 2021

Made available in DSpace on 2020-12-10T16:59:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Pro-reitoria de Pesquisa e Pos-graduacao from Universidade Federal de Minas Gerais In experiments with selection of perennial plants, the initial performance is expected to be maintained throughout the productive life. The probability of repeating the agronomic response can be evaluated by the repeatability coefficient. The objective was to estimate repeatability coefficients of agronomic characteristics in Panicum maximum Jacq. using different methods and identify the best combinations between harvests according to the genotypic stabilization. Seventeen genotypes were evaluated in a randomized complete block design with three replicates. The coefficients of repeatability were estimated by the methods: ANOVA, structural analysis based on the mean of the correlation coefficients (SACOR), analysis of principal components based on the covariance matrix (PCCOV) and correlation matrix (PCCOR). In the genotypic stabilization, coefficients estimated by ANOVA and PCCOR were used. For total DM, repeatability coefficients ranged from 0.3500 to 0.4300 by the ANOVA and PCCOR methods, respectively. High repeatability coefficients were found for the characteristic leaf DM, while low coefficients were observed for leaf and stem percentages and leaf:stem ratio. For the genotypic stabilization of total DM and leaf:stem ratio, the best coefficients were observed for the combination of harvests 5 to 8. There are variations in the estimate of repeatability by different methods and the highest coefficients were those of the principal components based on the correlation and covariance matrices. For the genotypic stabilization, the best coefficients of repeatability and determination were observed for the harvests performed in the second rainy period. Univ Estadual Paulista, Via Acesso Prof Paulo Donato Castelane, Jaboticabal, SP, Brazil Univ Fed Sao Joao del Rei, Ave Visconde do Rio Preto S-N, Sao Joao Del Rei, MG, Brazil Univ Fed Minas Gerais, Ave Univ 1000, Montes Claros, MG, Brazil Univ Estadual Sudoeste Bahia, Praca Primavera 40, Itapetinga, BA, Brazil Embrapa Gado Corte, Empresa Brasileira Pesquisa Agr, Campo Grande, MS, Brazil Univ Sao Paulo, Av Padua Dias 11,Cx Postal 9, Piracieaba, SP, Brazil Univ Fed Vales Jequitinhonha & Mucuri, Rodovia MGT 367 Km 583,5000 Alto Jacuba, Diamantina, MG, Brazil Univ Estadual Paulista, Via Acesso Prof Paulo Donato Castelane, Jaboticabal, SP, Brazil CAPES: 001

The effects of defoliation frequency (28, 35, 42 and 49 days) and defoliation intensity (30, 40 and 50 cm above the ground) on green dry matter (GDM) yield, and chemical composition of Panicum maximum cv. Mombaça were evaluated under natural field conditions at the Roraima ́s savannas. Defoliation regimes affect productivity and chemical composition of grass forage. The decrease in the pasture defoliation frequency and intensity improved the accumulation of forage, however it reduces the tissue concentrations of N, P, Ca, Mg and K. Irrespective of defoliation frequencies, the highest levels of N (23.99 g kg-1), P (2.12 g kg-1), Ca (4.22 g kg-1), Mg (2.87 g kg-1) and K (21.45 g kg-1) were recorded for the defoliation intensity at 40 cm above the ground. The use of defoliation frequency around 42 days and defoliation intensity of 42,9 cm above the ground can be considered adequate for the management of pastures of P. maximum cv. Mombaça, in order to provides higher forage productivity and quality, regrowth vigor, larger efficiency of forage utilization, greater tissue renewal and canopy structure more favorable to grazing. Made available in DSpace on 2021-08-04T14:04:04Z (GMT). No. of bitstreams: 1 RSD-2021-Forage-productivity-and-chemical-composition-of-Panicum-maximum-cv.-Mombaca-under-defoliations-intensities-and-frequencies.pdf: 197529 bytes, checksum: fa818da930760d565c0bc3dbda549b22 (MD5) Previous issue date: 2021

The effect of defoliation intensities (20, 30, 40 and 50 cm above soil level) on green dry matter (GDM) yield and morphogenetic and structural characteristics of Megathyrsus maximus cv. Centenário were evaluated under field conditions in Roraima´s savannas. The effects of defoliation intensities on the GDM yields, leaf area index and leaf elongation rates was adjusted to the quadratic regression model and maximum values recorded with cutting at 35.8; 44.9 and 30.2 cm above soil level, respectively. The tiller population density, number of leaves tiller-1 and leaf appearance rate was inversely proportional to the intensity of defoliation, while the opposite occurred for to average leaf length and leaf senescence rate. Apical meristem removal percentage was higher with increasing defoliation intensity. Vigor regrowth showed close negative correlation with defoliation intensity level. Pastures of M. maximus cv. Centenário managed under 30 to 35 cm residue provides higher forage productivity, larger efficiency of forage utilization, greater tissue renewal and canopy structure more favorable to grazing. El efecto de la intensidad de defoliación (20, 30, 40 y 50 cm por encima del suelo) sobre la producción de forraje y características morfogenéticas y estructurales de Megathyrsus maximus cv. Centenário se evaluó en las sabanas de Roraima. Los efectos de las intensidades de defoliación sobre la producción de materia seca verde, índice de área foliar y tasa de expansión de hojas fueron ajustados al modelo cuadrático de regresión y los máximos valores registrados con cortes a 35,8; 44,9 y 30,2 cm por encima del suelo, respectivamente. La densidad poblacional de macollas, la tasa de aparición de hojas y el número de hojas macolla-1 fueron inversamente proporcional a la intensidad de defoliación, ocurriendo lo contrario en cuanto a la longitud media de las hojas y la tasa de senescencia foliar. La eliminación de meristemos apicales se incrementó con el aumento de la intensidad de defoliación. El vigor de rebrote fue directo y negativamente correlacionado con la intensidad de defoliación. Pastos de M. maximus cv. Centenário manejados bajo residuos de 30 a 35 cm proporcionan mayor productividad y eficiencia de utilización del forraje, mayor renovación de tejidos y estructura del dosel más favorable al pastoreo. O efeito de intensidades de desfolhação (20, 30, 40 e 50 cm acima do solo) sobre a produção de forragem e características morfogênicas e estruturais de Megathyrsus maximus cv. Centenário foi avaliado em condições de campo nos cerrados de Roraima. Os efeitos das intensidades de desfolhação sobre a produção de matéria seca verde, índice de área foliar e taxa de expansão de folhas foram ajustados ao modelo quadrático de regressão e os máximos valores registrados com cortes a 35,8; 44,9 e 30,2 cm acima do solo, respectivamente. A densidade populacional de perfilhos, taxa de aparecimento de folhas e número de folhas perfilho-1 foram inversamente proporcionais à intensidade de desfolhação, ocorrendo o inverso quanto ao comprimento médio de folhas e taxa de senescência foliar. A eliminação de meristemas apicais foi incrementada com o aumento da intensidade de desfolhação. O vigor de rebrota foi direta e negativamente correlacionado com a intensidade de desfolhação. Pastagens de M. maximus cv. Centenário manejadas sob resíduos entre 30 a 35 cm proporcionam maior produtividade e eficiência de utilização da forragem, maior renovação de tecidos e estrutura do dossel mais favorável ao pastejo.

In this work were avaluated the effects of pasture rest periods on forage accumulation, chemical composition and morphogenic and structural characteristics of Megathyrsus maximus cv. Tamani in the Roraima´s savannas. Made available in DSpace on 2020-05-27T04:39:55Z (GMT). No. of bitstreams: 1 PubVet-2020-Desempenho-produtivo-composicao-quimica-RR.pdf: 426064 bytes, checksum: 17c74239ac356d03c8f6ed72d38db7b0 (MD5) Previous issue date: 2020 Título em Português: Desempenho produtivo, composição química e morfogênese de Megathyrsus maximus cv. Tamani sob períodos de descanso.

Made available in DSpace on 2020-12-10T09:09:02Z (GMT). No. of bitstreams: 1 1-Pasto-Certo-version-2.0-An-application-about-Brazilian-tropical-forage-cultivars-for-mobile-and-desktop-devices.pdf: 863590 bytes, checksum: ae5d39cfb70a7b726bbdad6e5a85dbc0 (MD5) Previous issue date: 2020

Made available in DSpace on 2020-12-12T22:28:01Z (GMT). No. of bitstreams: 1 5-High-Resolution-Linkage-Map-With-Allele.pdf: 1662161 bytes, checksum: f170934230a975599b17caabc555d7ed (MD5) Previous issue date: 2020

Made available in DSpace on 2020-04-29T04:38:28Z (GMT). No. of bitstreams: 1 RDS-2020-Caracteristicas-morfogenicas-e-estruturais-de-Megathyrsus-maximus-cv.-Centenario-sob-intensidades-de-desfolhacao1.pdf: 415463 bytes, checksum: 80253f1b9068111fc07abe6540190066 (MD5) Previous issue date: 2020

Genomic selection is an efficient approach to get shorter breeding cycles in recurrent selection programs and greater genetic gains with selection of superior individuals. Despite advances in genotyping techniques, genetic studies for polyploid species have been limited to a rough approximation of studies in diploid species. The major challenge is to distinguish the different types of heterozygotes present in polyploid populations. In this work, we evaluated different genomic prediction models applied to a recurrent selection population of 530 genotypes of Panicum maximum, an autotetraploid forage grass. We ,also investigated the effect of the allele dosage in the prediction, i.e., considering tetraploid (GS-TD) or diploid (GS-DD) allele dosage. A longitudinal linear mixed model was fitted for each one of the six phenotypic traits, considering different covariance matrices for genetic and residual effects. A total of 41,424 genotypingby- sequencing markers were obtained using 96-plex and Pst1 restriction enzyme, and quantitative genotype calling was performed. Six predictive models were generalized to tetraploid species and predictive ability was estimated by a replicated fivefold cross-validation process. GS-TD and GS-DD models were performed considering 1,223 informative markers. Overall, GS-TD data yielded higher predictive abilities than with GS-DD data. However, different predictive models had similar predictive ability performance. In this work, we provide bioinformatic and modeling guidelines to consider tetraploid dosage and observed that genomic selection may lead to additional gains in recurrent selection program of P. maximum. Made available in DSpace on 2019-12-31T00:38:25Z (GMT). No. of bitstreams: 1 GenomicSelectionwithAlleleDosage.pdf: 1504705 bytes, checksum: 070a9fc1afa0161e4c6ea7502c5f52f8 (MD5) Previous issue date: 2019

Made available in DSpace on 2019-06-26T00:40:18Z (GMT). No. of bitstreams: 1 2019RDSRespostadepastagensdeMegathyrsusmaximuscv.Zuriafrequenciadedesfolhacao.pdf: 222339 bytes, checksum: 6b2b471330f22f7a596aacd5b04beaf8 (MD5) Previous issue date: 2019

In experiments with selection of perennial plants, the initial performance is expected to be maintained throughout the productive life. The probability of repeating the agronomic response can be evaluated by the repeatability coefficient. The objective was to estimate repeatability coefficients of agronomic characteristics in Panicum maximum Jacq. using different methods and identify the best combinations between harvests according to the genotypic stabilization. Seventeen genotypes were evaluated in a randomized complete block design with three replicates. The coefficients of repeatability were estimated by the methods: ANOVA, structural analysis based on the mean of the correlation coefficients (SACOR), analysis of principal components based on the covariance matrix (PCCOV) and correlation matrix (PCCOR). In the genotypic stabilization, coefficients estimated by ANOVA and PCCOR were used. For total DM, repeatability coefficients ranged from 0.3500 to 0.4300 by the ANOVA and PCCOR methods, respectively. High repeatability coefficients were found for the characteristic leaf DM, while low coefficients were observed for leaf and stem percentages and leaf:stem ratio. For the genotypic stabilization of total DM and leaf:stem ratio, the best coefficients were observed for the combination of harvests 5 to 8. There are variations in the estimate of repeatability by different methods and the highest coefficients were those of the principal components based on the correlation and covariance matrices. For the genotypic stabilization, the best coefficients of repeatability and determination were observed for the harvests performed in the second rainy period. Made available in DSpace on 2019-12-31T00:38:51Z (GMT). No. of bitstreams: 1 Repeatabilityandgenotypicstability.pdf: 375500 bytes, checksum: ebdf11750194b8c14759b604db7f7927 (MD5) Previous issue date: 2019

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico Outra Agência A adubação nitrogenada modifica os padrões morfogênicos de crescimento das forrageiras. Logo, estudos sobre a resposta de plantas recém lançadas, como a capim BRS Quênia, à adubação podem contribuir sobremaneira com a recomendação estratégias de manejo e doses mais apropriadas do adubo. Objetivou-se com este trabalho avaliar a alocação de biomassa aérea e radicular, resposta morfogênica e a eficiência agronômica da adubação em plantas de Panicum maximum cv. BRS Quênia, sem adubação e adubadas com 50, 100 e 200 mg.dm-3 de nitrogênio. O experimento foi conduzido em casa de vegetação, em delineamento inteiramente casualizado com quatro repetições. As proporções de folha foram maiores que as proporções de colmo, independentemente da adubação nitrogenada. Houve maiores incrementos na produção de parte aérea em detrimento a produção de raiz. O aumento da adubação implicou em menor intervalo entre o surgimento das folhas do capim BRS Quênia, bem como aumentou o número de perfilhos por planta. A medida que se incrementa a adubação nitrogenada há diminuição da eficiência de uso do adubo. A adubação nitrogenada influencia positivamente a produção de forragem em plantas de Panicum maximum BRS Quênia e, independentemente da dose de adubação nitrogenada, a parte aérea funciona como principal dreno de nitrogênio. Nitrogen fertilization modifies the morphogen patterns of forage growth. Therefore, studies on the response of newly introduced plants, such as BRS Quênia, to fertilization can contribute greatly with the recommendation of management strategies and more appropriate doses of fertilizer. The objective with this research was to evaluate aboveground and root dry mass production and the morphogenetic and structural characteristics, as well as the agronomic efficiency of nitrogen fertilization in Panicum maximum cv. BRS Quênia, without fertilization and submitted to nitrogen levels (50, 100 and 200 mg/dm3). The experiment was conducted in the greenhouse in a completely randomized design whit four replication. Production characteristics and morphogenetic and structural characteristics of the plants were evaluated. The grass BRS Quênia responded to nitrogen fertilization for all characteristics evaluated. Leaf proportions were higher than stem proportions, regardless of nitrogen fertilization. There were larger increases in aboveground mass production than root production. The increase in fertilization implied in a shorter interval between the emergence of leaves of BRS Quênia grass, as well as increased number of tillers per plant. As nitrogen fertilization increases, there is a decrease in fertilizer efficiency. Nitrogen fertilization positively influences forage production in Panicum maximum BRS Quênia plants and, independently of nitrogen dosage, the aboveground mass acts as the main nitrogen drain.

Ainda há muitas cultivares por vir, cada uma com vantagens específicas. A tendência é que sejam liberadas espécies menos generalistas, sou seja, adaptadas às demandas específicas do setor produtivo.

Made available in DSpace on 2018-05-16T00:47:46Z (GMT). No. of bitstreams: 1 PubVet2018RendimentodeforragemcomposicaoquimicaemorfogenesedeMegathyrsusmaximuscv.Tanzania1sobfrequenciasdedesfolhacao.pdf: 455112 bytes, checksum: cb4bd5dcb30c5dfd3358d2717567d63c (MD5) Previous issue date: 2018-05-15

This study aimed to isolate and identify endophytic fungi from the forage grass P. maximum and evaluate their ability to inhibit the growth of plant pathogenic fungi. One sample from P. purpureum grass was also included. Surface disinfected stem fragments were used for endophytic fungal isolation. One hundred and twenty-six endophytic fungi were isolated, of which 118 were from P. maximum and eight from P. purpureum. Morphological characteristics and internal transcribed spacer (ITS) and 18S (NS) sequence comparisons identified most isolated endophytic fungi as belonging to the phylum Ascomycota, with Sarocladium being the dominant genus. The isolates were subjected to in vitro antagonism tests against pathogenic fungi, and 31 endophytic fungi inhibited the growth of Bipolaris maydis, Penicillium expansum, and Sclerotinia minor. The results expand our knowledge of the diversity of endophytes associated with tropical grasses and suggest that they may represent new sources of antifungal metabolites for biocontrol and biotechnological purposes. Made available in DSpace on 2019-07-05T00:52:54Z (GMT). No. of bitstreams: 1 FungalendophytesofPanicummaximum.pdf: 308948 bytes, checksum: 906943033eabb016539b917e21260361 (MD5) Previous issue date: 2018

O efeito de intensidades de desfolhação (20, 30, 40 e 50 cm acima do solo) sobre a produção de forragem e características morfogênicas e estruturais de Megathyrsus maximus cv. Tanzânia-1 foi avaliado nos cerrados de Roraima. Made available in DSpace on 2018-06-07T01:07:52Z (GMT). No. of bitstreams: 1 PUBVETv12Caracteristicas.pdf: 496557 bytes, checksum: c5e604a57937d59cd386f376df9f92c8 (MD5) Previous issue date: 2018-06-06

Made available in DSpace on 2017-09-27T10:31:19Z (GMT). No. of bitstreams: 1 PubVet2017ProdutividadedeforragemcomposicaoquimicaemorfogenesedeMegathyrsusmaximuscv.Mombacasobperiodosdedescanso.pdf: 327288 bytes, checksum: 5adcd5df5ee678f658ac86c17a047186 (MD5) Previous issue date: 2017-09-26

Made available in DSpace on 2017-09-27T10:30:59Z (GMT). No. of bitstreams: 1 PubVet2017AcumulodeforragememorfogenesedeMegathyrsusmaximuscv.Mombacasobniveisdefosforo1.pdf: 381179 bytes, checksum: dbdf8b04f09c627d5ffebf8378eb7c66 (MD5) Previous issue date: 2017-09-26

Selection of superior forage genotypes is based on agronomic traits assayed in repeated measures. The questions are how repeatable the performance of individual genotypes is and how many harvests are needed to select the best genotypes. The objectives were to estimate repeatability coefficients of dry matter yield (DMY) and forage quality, their phenotypic stability and the number of harvests needed for an accurate selection. Two randomized complete block design experiments data with 24 genotypes each, undergoing 12 and 16 harvests, over a period of 2 and 3 years, respectively, were used. The DMY repeatability estimates ranged from 0.42 to 0.55, suggesting a low heritability. The mean numbers of repeated measures were 5 and 7 harvests for 0.80 and 0.85 accuracy, respectively. The inclusion of the first two harvests negatively affects the estimates. Repeatability for quality traits ranged from 0.30 to 0.69, indicating low to moderate heritability. Made available in DSpace on 2017-10-14T10:33:19Z (GMT). No. of bitstreams: 1 RepeatabilitynumberofharvestsandphenotypicstabilityofdrymatteryieldandqualitytraitsofPanicummaximumjacq.pdf: 157585 bytes, checksum: 750e23dd26d49456c87b8fcf5956887b (MD5) Previous issue date: 2017-10-13 Título em português: Repetibilidade, número de colheitas e estabilidade fenotípica da produção de matéria seca e de características de qualidade de Panicum maximum jacq.

Made available in DSpace on 2019-03-23T00:42:39Z (GMT). No. of bitstreams: 1 84139671PB.pdf: 1217108 bytes, checksum: 7d4aae8e8bf35fb6c64c9db451f605f4 (MD5) Previous issue date: 2016

O experimento foi conduzido objetivando-se determinar os coeficientes de repetibilidade, por quatro métodos (Análise de Variância, de Componentes prin-cipais - matriz de correlação e covariância e a Análise estrutural), o número de cortes necessários para aumento de acurácia e a estabilização fenotípica de características de produção em acessos de Panicum maximum. O experimento foi conduzido em delineamento inteiramente casualizado com 35 genótipos e três repetições. Foram realizados cinco cortes e as amostras foram pesadas e secas para obtenção da produção de matéria seca total, de colmo, folhas e material morto. Os coeficientes de repetibilidade nos diferentes métodos, para todas as características, oscilaram entre 0,1867 e 0,6583. As estimativas da repetibilidade obtidas pelo método da análise de variância foram quase sempre menores que as obtidas pelos demais métodos. Pelo método dos componen-tes principais (baseado na matriz de covariância), as estimativas foram sempre maiores em relação aos demais métodos. Portanto, é possível recomendar esse método para estimativas do coeficiente de repetibilidade para as características avaliadas nesse estudo. Considerando satisfatórios os níveis de 80 ou 90% de confiabilidade para avaliação da superioridade relativa dos acessos para todas as características avaliadas, as cinco medições realizadas são suficientes para escolha do melhor acesso.

Objetivou-se com este trabalho avaliar a diversidade genética e a importância relativa de caracteres morfológicos para o estudo da diversidade genética em genótipos de Stylosanthes capitata com base em caracteres morfológicos. Foram avaliadas 10 famílias de polinização aberta (297-2, 49-5, 1064-4, 49-4, 1095-5, 141-6, 1064-6, 297-6, 625-3, 111-3), previamente selecionadas pelo programa de melhoramento da Embrapa Gado de Corte e a cultivar Campo Grande como testemunha. O delineamento experimental foi inteiramente casualizado, com quatro repetições. Foram avaliadas as características morfológicas: forma de crescimento, comprimento, largura, relação comprimento:largura dos folíolos centrais e laterais, altura da planta, comprimento da haste e número de ramificações secundárias. A matriz de distância generalizada do Mahalanobis foi obtida utilizando-se as médias fenotípicas para cada característica e a matriz de variâncias e covariâncias residuais. Em posse da matriz de dissimilaridade, as famílias e a cultivar Campo Grande foram agrupadas utilizando o método de Ward. A análise de variáveis canônicas (VC) também foi realizada utilizando-se a média fenotípica dos caracteres avaliados e a matriz de variâncias e covariâncias residuais. Por meio da análise de agrupamento pelo método de Ward foi possível reunir os 11 genótipos em cinco grupos. A análise de variáveis canônicas foi realizada com grande eficiência, pois permitiu resumir a variação total observada nos nove caracteres morfológicos em apenas três VC, que acumularam 81,65% da variação total dos dados. Também foi possível realizar o estudo da importância das características para o agrupamento. Os caracteres morfológicos largura do folíolo central, relação comprimento largura dos folíolos central e lateral, largura do folíolo lateral e ramificações secundárias figuram entre os de maior importância para a avaliação da diversidade genética entre genótipos de Stylosanthes capitata. Made available in DSpace on 2018-02-24T00:38:04Z (GMT). No. of bitstreams: 1 57DiversidadegeneticaemacessosdeStylosanthescapitata2015.pdf: 274562 bytes, checksum: 09af0142501aa816d7d92c3f5714cea5 (MD5) Previous issue date: 2018-02-23

The objective of this study was to evaluate the genotypic stability of agronomic traits in hybrids of Panicum maximum. Hybrids originating from the crosses between two sexual parents and cultivars Mombasa and Tanzania were evaluated in an incomplete-block design. Evaluated traits were total dry matter, leaf dry matter, stem dry matter, percentage of leaves, and leaf:stem ratio. These traits were evaluated in six harvests. Overall, higher repeatability was observed for the traits total dry matter and leaf dry matter, especially when harvests 4, 5, and 6, occurring in spring and summer, were evaluated. The leaf dry matter was the trait that provided the greatest repeatability and determination. The repeatability of stem dry matter, percentage of leaves, and leaf:stem ratio had a low magnitude, even when the coefficient was estimated based on the harvests of better stabilization for the other variables. The hybrids achieved genotypic stabilization in the harvests made in the second rainy season. Harvests made in the rainy season provide greater repeatability and determination, and the inclusion of the dry-season harvest is detrimental to the process of selection of low-repeatability traits such as percentage of leaves. Made available in DSpace on 2018-02-23T00:32:09Z (GMT). No. of bitstreams: 1 48GenotypicstabilizationofagronomictraitsinPanicummaximumJacq.hybrids2015.pdf: 726903 bytes, checksum: 1c995621037287f847ae6795baa494d1 (MD5) Previous issue date: 2018-02-22

The silvopastoral system is a viable technological alternative to extensive cattle grazing, however, for it to be successful, forage grass genotypes adapted to reduced light need to be identified. The objective of this study was to select progenies of Panicum maximum tolerant to low light conditions for use in breeding programs and to study the genetic control and performance of some traits associated with shade tolerance. Six full-sib progenies were evaluated in full sun, 50% and 70% of light reduction in pots and subjected to cuttings. Progeny genotypic values (GV) increased with light reduction in relation to plant height (H) and specific leaf area (SLA). The traits total dry mass accumulation (DM) and leaf dry mass accumulation (LDM) had GV higher in 50% shade and intermediate in 70% shade. The GV of tiller number (TIL) and root dry mass accumulation (RDM) decreased with light reduction. The highest positive correlations were obtained for the traits H and RDM with SLA and DM; the highest negative, correlations were between TIL and SLA and RDM, and H and LDM. The progenies showed higher tolerance to 50% light reduction and, among them, two stood out and will be used in breeding programs. It was also found that it is not necessary to evaluate some traits under all light conditions. All traits had high broad sense heritability and high genotypic correlation between progenies in all light intensities. There is genetic difference among the progenies regarding the response to different light intensities, which will allow selection for shade tolerance.

Soil fertility of the Brazilian savanna (Cerrado) is natu-rally poor. Extensive areas of pastures located in the central part of the territory are cultivated with Brachiaria grasses, which are less demanding for soil nutrients and lime than other species (Rao et al. 1998). On the other hand, Panicum maximum cultivars, such as the high yielding Mombaça grass recommended for intensive beef and dairy cattle systems (Euclides et al. 2008), must be seeded with a higher amount of fertilizer, especially phosphorus (P). Consequently, an effort is underway to select P. maximum genotypes with low P demand and high responsiveness. The objective of this study was to evaluate dry matter yields of genotypes of P. maximum in response to doses of P and lime in the Brazilian Cerrado. Made available in DSpace on 2018-12-14T00:00:15Z (GMT). No. of bitstreams: 1 44DrymatteryieldofpromisingPanicummaximumgenotypesinresponsetophosphorusandlimingonBraziliansavannah2013.pdf: 327728 bytes, checksum: 22b9adda626c4c02b17769afe08831fa (MD5) Previous issue date: 2018-02-22

Made available in DSpace on 2020-04-24T14:32:55Z (GMT). No. of bitstreams: 1 v71n1a03-SA-2013-0102.indd-Scientia-agricola-v71n1a03.pdf: 4102879 bytes, checksum: 3ccf96841dfbdb4858131169a3843d04 (MD5) Previous issue date: 2014

Guinea grass (Panicum maximum Jacq.) is a tropical African grass often used to feed beef cattle, which is an important economic activity in Brazil. Brazil is the leader in global meat exportation because of its exclusively pasture-raised bovine herds. Guinea grass also has potential uses in bioenergy production due to its elevated biomass generation through the C4 photosynthesis pathway. We generated approximately 13 Gb of data from Illumina sequencing of P. maximum leaves. Four different genotypes were sequenced, and the combined reads were assembled de novo into 38,192 unigenes and annotated; approximately 63% of the unigenes had homology to other proteins in the NCBI non-redundant protein database. Functional classification through COG (Clusters of Orthologous Groups), GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses showed that the unigenes from Guinea grass leaves are involved in a wide range of biological processes and metabolic pathways, including C4 photosynthesis and lignocellulose generation, which are important for cattle grazing and bioenergy production. The most abundant transcripts were involved in carbon fixation, photosynthesis, RNA translation and heavy metal cellular homeostasis. Finally, we identified a number of potential molecular markers, including 5,035 microsatellites (SSRs) and 346,456 single nucleotide polymorphisms (SNPs). To the best of our knowledge, this is the first study to characterize the complete leaf transcriptome of P. maximum using highthroughput sequencing. The biological information provided here will aid in gene expression studies and marker-assisted selection-based breeding research in tropical grasses.

This experiment was carried out with the objectives of determining repeatability coefficients, the number of harvests necessary to increase accuracy and the genotypic stability of yield characteristics in Brachiaria brizantha cultivars in the northeast region of Brazil in the period from July 2009 to March 2011. The experimental design used was completely randomized with three treatments (Brachiaria brizantha var. Marandu, Xaraés and Piatã) and three replications. Each plot was harvested seven times: five in the rainy season and two in the dry season. Immediately after each harvest, the forage was weighed and dried to obtain total, stem, leaf and dead dry matter yields. For the estimation of the repeatability coefficient, analysis of variance, principal components (correlation and covariance matrices) and structural analyses were used. The repeatability coefficients (r) obtained by the different methods, for all characteristics evaluated, varied from 0.009 to 0.837. The estimates of the repeatability coefficients obtained for all characteristics evaluated by the method of analyses of variance were almost always lower than those obtained by the other methods. By the principal components method (based on the covariance matrix), the estimates were always higher than those from other methods. Considering that levels of 80 or 90% confidence are satisfactory in the evaluation of the relative superiority of the cultivars for all the evaluated characteristics, with the exception of dead matter yield, the seven harvests are sufficient for the choice of the best cultivar to be used in the northeast region of Brazil. Made available in DSpace on 2018-02-23T00:31:44Z (GMT). No. of bitstreams: 1 46RepeatabilityofagronomiccharactersinBrachiariabrizanthacultivars2013.pdf: 322049 bytes, checksum: 2a2969945ae1898faeae823b4f673faa (MD5) Previous issue date: 2018-02-22

The Panicum maximum breeding program coordinated by the Brazilian Agricultural Research Corporation (Embrapa) has been evaluating and selecting genotypes under different soil and climatic conditions, with the objective to release new cultivars adapted to the diverse regions of Brazil. For the Amazon biome, small-plot experiments carried out in Acre between 2003 and 2005 allowed the selection of some promising genotypes (Valentim and Andrade 2005; Valentim et al. 2006; Andrade and Valentim 2009), with higher potential for forage growth than cultivars on the market. The objec-tive of this work was to compare 2 new P. maximum genotypes with cv. Tanzânia in relation to carrying ca-pacity and animal performance, when managed under rotational stocking in the Amazon biome. Publicado também nos Anais do 22º INTERNATIONAL GRASSLAND CONGRESS, Sidney, 2013.

O objetivo deste trabalho foi avaliar as características anatômicas e morfofisiológicas de lâminas foliares de genótipos de Panicum maximum e determinar quais as mais relevantes para a discriminação precoce do valor nutritivo de genótipos promissores. O experimento foi realizado entre janeiro de 2006 e novembro de 2007, em Dourados, MS. Foram avaliados 23 genótipos de P. maximum pré-selecionados do programa de melhoramento da Embrapa Gado de Corte. Utilizou-se o delineamento experimental de blocos ao acaso, com três repetições. Foram avaliadas 27 características anatômicas e morfofisiológicas de lâminas foliares em cada genótipo. Para cada característica estudada, os resultados foram agrupados pelo teste de Scott‑Knott. A importância relativa das características avaliadas para a avaliação da divergência genética foi determinada pelo método de Singh. As características que melhor discriminaram os genótipos foram as proporções ? na seção transversal das lâminas ? das epidermes adaxial, abaxial, adaxial + abaxial, do mesofilo e do tecido vascular + esclerênquima. A área foliar específica, a área foliar e o comprimento de lâmina foram as características morfofisiológicas que mais contribuíram para a discriminação dos genótipos; porém, sua importância relativa foi muito menor que a das características anatômicas. A proporção ocupada pela bainha parenquimática dos feixes e a largura das lâminas apresentam instabilidade fenotípica.

The Guineagrass (Panicum maximum Jacq.) is one of the most important tropical forage grasses, but genetic knowledge and tools regarding this species are still limited. Therefore, 20 novel polymorphic microsatellite markers were developed, validated, and employed in estimating genetic relationships among 25 P. maximum genotypes selected from a Brazilian germplasm collection. In addition, they were tested for cross-species amplification in four other forage grass species. The number of alleles observed for each locus ranged from 4 to 12 (average 6.7). The values of polymorphism information content (PIC) varied from 0.41 to 0.83 (average 0.61) and the discriminating power (D) ranged from 0.53 to 0.98 (average 0.72). Cross-amplification demonstrated the potential transferability of these microsatellites to four tropical forage grass species. Cluster analysis based on the unweighted pair group method revealed three distinct groups: two clusters consisted of P. maximum genotypes and a third cluster, consisted of the other tropical forage grass species. The data demonstrated that the microsatellites developed herein have potential for germplasm characterization and genetic diversity analysis in P. maximum and other forage grass species.

A utilização de marcadores moleculares pode servir para direcionar cruzamentos, confirmar novos híbridos e identificar genótipos para fins comerciais. Nesse contexto, o objetivo deste trabalho foi analisar a diversidade genética entre cultivares e híbridos de Brachiaria spp. e Panicum maximum usando marcadores moleculares do tipo RAPD (Polimorfismos de DNA amplificados ao acaso). Foram 22 genótipos analisados com 10 primers, os quais amplificaram 178 fragmentos polimórficos de DNA, que foram usados para estimar a similaridade genética por meio do coeficiente de Jaccard. Os valores de similaridade obtidos variaram de 0,066 a 0,841. A estrutura genética entre todos os genótipos estudados foi estimada pelo método UPGMA (Método de agrupamento com médias aritméticas não ponderadas), revelando três grupos distintos com altos valores de bootstrap (>89%). Os resultados demonstraram que a técnica RAPD oferece uma maneira rápida, relativamente barata e útil para a caracterização da diversidade genética entre as diferentes cultivares e híbridos de Brachiaria ssp. e P. maximum analisados

A genetically diverse population of Setaria sphacelata was developed at Gainesville, Florida by intercrossing the cultivars ?Narok?, ?Kazungula? and ?Solander? and a local persistent population. To determine heritability of traits that may improve setaria as a forage plant in Florida, progeny of the intercrossed population underwent two cycles of selection for inflorescence number and one cycle for leaf width. The selected populations, together with cultivars and introductions, were evaluated for morphological characters, yield and forage quality in field experiments with close- and wide-spaced plants. Increase of inflorescence number was not obtained by selection but resulted in decreased plant height, inflorescence length, yield, leaf width, and leafiness. Leaf width was increased by selection and was associated with increased leafiness and whole-plant crude protein content. The results suggest good prospects for selection of setaria cultivars suited to Florida with improved yield and quality providing they tolerate winter cold and reliably produce seed.

Recursos genéticos das pastagens. O melhoramento das espécies de pastagens. Progaramas de melhoramento genético de pastagens no Brasil. Made available in DSpace on 2020-04-24T00:42:18Z (GMT). No. of bitstreams: 1 Geneticaempastagem.pdf: 224070 bytes, checksum: d9160eefb856bd3b5adfbaccde1d7527 (MD5) Previous issue date: 2005

O trabalho foi realizado com o objetivo de avaliar a produção de B. decumbens cv. Basilisk e B. brizantha, cultivares Marandu e Xaraés, sob diferentes níveis de sombreamento. Utilizou-se delineamento em blocos casualizados com esquema de parcelas subdivididas, considerando os níveis de sombreamento (0, 50, 70%) como parcela e as espécies ou cultivares como subparcelas. Sementes das gramíneas foram postas a germinar em bandejas e transplantadas (três plântulas por vaso). Foram realizados quatro cortes em cada subparcela. Antes de cada corte, mediram-se a altura de planta e a área foliar de quatro folhas em cada planta e quantificou-se o número de perfilhos vivos por vaso. Após a colheita, as plantas foram separadas em lâmina, colmo + bainha e material morto para determinação da produção de matéria seca. Para produção de matéria seca total, calcularam-se a produção média em cada um os cortes e a produção total. No último corte, avaliou-se a massa seca de raízes. As interações significativas foram desdobradas adequadamente. O fator qualitativo foi submetido à comparação de médias pelo teste Tukey e o quantitativo à análise de regressão linear. À exceção da produção média em quatro cortes e da produção de colmos e de material morto, observou-se interação significativa para todas as outras variáveis. Independentemente do nível de sombreamento, o cultivar Xaraés destacou-se positivamente na maioria das características analisadas, enquanto, no nível de 50% de sombreamento, o capim-braquiária apresentou maior produtividade, em porcentagem de produção a pleno sol. Na avaliação da porcentagem de folhas, destacou-se o capim-xaraés, seguido do capim-marandu. Independentemente da forrageira, o nível de sombreamento teve efeito direto sobre o número de perfilhos/planta, a produção de MS do sistema radicular, a área foliar e o valor SPAD. Yields of B. decumbens cultivar Basilisk and B. brizantha cultivars Marandu and Xaraés were evaluated under different shade levels. A completely randomized block split plot design was used, with the shade levels as plots (0, 50, 70%), and the species and cultivars as split-plots. Seeds were germinated on trays and three seedlings were transplanted to each pot. Four harvests were made on each split-plot. Prior to each harvest, plant height, number of live tiller per pot and the leaf area of four leaves per pot were recorded. After harvesting, the plants were separated into leaves, stem + sheaths and dead matter to determine dry matter yield. Total dry matter yield was calculated for each harvest and for the sum of harvests. In the last harvest, root dry matter yield was also evaluated. Significant interactions were unfolded adequately. The means of the qualitative factor (forages) were compared by the Tukey test and the quantitative factor (shade level) was submitted to linear regression analysis. With the exception of the mean yield in four harvests and stem and dead matter yield, significant interaction was detected for all other variables. Regardless of the shade level, the Xaraés cultivar presented the highest values in most of the variables analyzed, while B. decumbens presented the lowest yield in all levels of shade. Regarding leaf percentage, cv. Xaraés revealed the highest results, followed by cv. Marandu. Regardless of the forage grass, the shade level affected directly the number of tillers/plant, root dry matter yield, leaf area and SPAD value.

EnglishGenetic breeding of forage plants has increasingly contributed to the release of more productive plants. In this regard, evaluating the genotypic value is essential when aiming to rank genotypes based on the mean free of environmental factors. Therefore, this study aimed to predict the genotypic value of agronomic and nutritive value characters of three progenies of Panicum maximum. Hybrids were evaluated in a clonal test in an incomplete-randomized design with three treatments (progenies 1, 2, and 3) and two replications (clones). Six harvests were performed at 25cm from the ground level throughout one year. Progeny 2 provided better results for total and leaf dry mass yield, regrowth, and height, and lower incidence of leaf spot. Progenies 1 and 3 had a better response for qualitative characters such as higher crude protein and digestibility and lower lignin and fiber content. Hybrid progenies of P. maximum have forage characters of interest for breeding, and when using ‘Mombaca’ grass as parents, the progeny stands out for leaf production and resistance to leaf spot and for ‘Tanzania’ grass as parent has resulted in better forage quality. Key words: Bipolaris maydis; chemical composition; leaf biomass; ‘Mombaca’; ‘Tanzania’ portuguesO lancamento de forrageiras resultantes de programas de melhoramento genetico tem sido importante fonte de liberacao de novas forrageiras mais adaptadas e competitivas. Nessas situacoes, a avaliacao do valor genetico e essencial quando se objetiva ranquear os genotipos com base no valor genotipico, isento dos efeitos ambientais. O objetivo com este trabalho foi estimar e avaliar o valor genotipico de caracteristicas agronomicas e de valor nutritivo de tres progenies de P. maximum, resultantes do cruzamento entre duas progenitoras sexuais e as cultivares ‘Mombaca’ e ‘Tanzânia’. O experimento foi implantado em teste clonal no delineamento em blocos incompletos com tres tratamentos (progenies 1, 2 e 3) com duas repeticoes (clones). Os hibridos foram manejados por meio de cortes na altura de 25cm do nivel do solo por um ano, realizando seis cortes. A progenie 2 proporcionou melhores resultados para producao de folhas, rebrota, altura de planta e baixa incidencia de mancha foliar causada por Bipolaris maydis. As progenies 1 e 3 apresentaram, em media, melhores resultados para caracteristicas qualitativas como proteina bruta e digestibilidade e menor teor de lignina. As progenies hibridas de P. maximum apresentam caracteristicas forrageiras de interesse para o melhoramento, sendo que a utilizacao do capim-mombaca como parental proporciona maior producao de folhas e resistencia a mancha foliar, ao passo que o capim-tanzânia como parental proporciona melhoria da qualidade da forragem. Palavras-chave: Bipolaris maydis; composicao bromatologica; biomassa de folhas; ‘Mombaca’; ‘Tanzânia’