Characterization and genetic diversity in Paspalum notatum Flügge accessions: Morphological and geographical distance

The objective of this work was to describe morphology and grouping of Paspalum notatum accessions, based on multicategorical data which discards the redundant variables for quantification of genetic diversity. We also tested the hypothesis that geographical distance was correlated with morphological divergence. In our study, multivariate analyzes successfully demonstrated the geographic and morphological variability of the P. notatum accessions characterized. Many of these evaluated accessions can be included in future genetic improvement programs. Based on two methodologies for discarding variables, it was possible to identify the potentially important morphological characteristics from genetic diversity studies and characterize new accessions aimed at improving forage and seed production. The methodologies used to discard variables are biometric tools that can be used successfully in future plant breeding programs, especially when a large number of traits and accessions are being evaluated. Although significant, geographic distance had a low association with morphological traits. This indicated the need to use other characteristics, such as forage and seed yield, in addition to molecular analysis. Our analyzes showed genetic variability in P. notatum for all the characteristics studied.(AU)

Multivariate analysis reveals genetic diversity in Paspalum notatum Flügge

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.

Response of Bahiagrass hybrids to nitrogen fertilization or mixture with legumes

The objective of this work was to determine Paspalum notatum genotypes appropriate for the establishment of mixtures with temperate legumes and compare the productivity of mixtures with mineral-fertilized systems along two years. Four hybrids of P. notatum, ecotype Bagual and cv. Pensacola, were either subjected to mixtures with white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus) or fertilized with 0, 60, 120, 240, and 480 kg N ha−1 year−1. P. notatum leaf blades and stems and herbage accumulation denoted a management × year interaction. Herbage accumulation varied between the mixtures and fertilized systems in first year, while in the second year, herbage accumulation of mixed systems employing the B26, B43, C22, C9, and Bagual genotypes were similar to that of systems fertilized with 120 and 240 kg N ha−1. Hybrids B26 and C9 and ecotype Bagual, once made available to producers, could be indicated for mixtures with temperate legumes because they are superior to cv. Pensacola. Herbage accumulation in mixtures involving white clover plus birdsfoot trefoil and P. notatum genotypes is similar to that of mineral nitrogen-fertilized systems with 240 kg N ha−1, emphasizing the viability of mixed between these species.

Estimativa da conversão em produto animal a partir do uso de Avena strigosa schreb submetida a diferentes fontes e doses de nitrogênio / Estimation of conversion in animal product from the use of Avena strigosa schreb submitted to different nitrogen sources and doses

O objetivo do presente estudo foi avaliar a resposta agronômica e econômica da pastagem de aveia preta (cv. Embrapa 29 Garoa) submetida a diferentes fontes e doses de fertilização nitrogenada. O delineamento experimental utilizado foi o de blocos ao acaso, organizado em esquema fatorial: duas fontes de Nitrogênio x cinco doses de fertilização x três cortes. Trezentos resultados obtidos demonstraram que a cultura da aveia preta responde em potencial produtivo a partir de diferentes fontes e doses de fertilização nitrogenada, impactando de maneira diferenciada sobre o produto animal. A escolha da dose de fertilização dentro das distintas fontes de Nitrogênio depende da eficiência de utilização do Nitrogênio em produção de forragem e a sua conversão em produção animal, aliado à remuneração do produto e custos envolvidos com a implantação da pastagem. A aplicação de ureia como fonte de Nitrogênio proporcionou maior produção de matéria seca por corte na cultura de aveia preta quando comparado ao sulfato de amônio. As maiores eficiências de utilização de nitrogênio foram obtidas com a aplicação de 45 kg ha-1 de ureia e sulfato de amônio. A cultura de aveia preta responde biologicamente até a dose de fertilização nitrogenada de 90 kg de N ha-1. As aplicações de 45 kg de N ha-1 na forma de ureia e 23 kg ha-1 de sulfato de amônio foram economicamente viáveis nas condições em que o estudo foi realizado.

The objective of this study was to evaluate the agronomic and economic response of black oat pasture (cv. Embrapa 29 Garoa) submitted to different nitrogen fertilization sources and doses. The experimental design used was a randomized block design, arranged in a factorial scheme: two sources of nitrogen x five fertilization doses x three cuts. Three hundred results obtained demonstrated that black oat crop responds in productive potential from different sources and doses of nitrogen fertilization, impacting differently on the animal product. The choice of fertilization dose within the different sources of nitrogen will depend on the efficiency of nitrogen utilization in fodder production and its conversion to animal production, coupled with the product remuneration and costs involved with pasture implantation. The application of urea as nitrogen source provided greater production of dry matter per cut in black oat culture when compared to ammonium sulfate. The highest efficiencies in the use of nitrogen were obtained by applying 45 kg ha-1 of urea and ammonium sulfate. Black oat culture responds biologically to the nitrogen fertilization dose of 90 kg N ha-1. The applications of 45 kg of N ha-1 in the form of urea and 23 kg ha-1 of ammonium sulfate were economically feasible under the conditions in which the study was carried out.

Estimativa da conversão em produto animal a partir do uso de Avena strigosa schreb submetida a diferentes fontes e doses de nitrogênio / Estimation of conversion in animal product from the use of Avena strigosa schreb submitted to different nitrogen sources and doses

O objetivo do presente estudo foi avaliar a resposta agronômica e econômica da pastagem de aveia preta (cv. Embrapa 29 Garoa) submetida a diferentes fontes e doses de fertilização nitrogenada. O delineamento experimental utilizado foi o de blocos ao acaso, organizado em esquema fatorial: duas fontes de Nitrogênio x cinco doses de fertilização x três cortes. Trezentos resultados obtidos demonstraram que a cultura da aveia preta responde em potencial produtivo a partir de diferentes fontes e doses de fertilização nitrogenada, impactando de maneira diferenciada sobre o produto animal. A escolha da dose de fertilização dentro das distintas fontes de Nitrogênio depende da eficiência de utilização do Nitrogênio em produção de forragem e a sua conversão em produção animal, aliado à remuneração do produto e custos envolvidos com a implantação da pastagem. A aplicação de ureia como fonte de Nitrogênio proporcionou maior produção de matéria seca por corte na cultura de aveia preta quando comparado ao sulfato de amônio. As maiores eficiências de utilização de nitrogênio foram obtidas com a aplicação de 45 kg ha-1 de ureia e sulfato de amônio. A cultura de aveia preta responde biologicamente até a dose de fertilização nitrogenada de 90 kg de N ha-1. As aplicações de 45 kg de N ha-1 na forma de ureia e 23 kg ha-1 de sulfato de amônio foram economicamente viáveis nas condições em que o estudo foi realizado.(AU)

The objective of this study was to evaluate the agronomic and economic response of black oat pasture (cv. Embrapa 29 Garoa) submitted to different nitrogen fertilization sources and doses. The experimental design used was a randomized block design, arranged in a factorial scheme: two sources of nitrogen x five fertilization doses x three cuts. Three hundred results obtained demonstrated that black oat crop responds in productive potential from different sources and doses of nitrogen fertilization, impacting differently on the animal product. The choice of fertilization dose within the different sources of nitrogen will depend on the efficiency of nitrogen utilization in fodder production and its conversion to animal production, coupled with the product remuneration and costs involved with pasture implantation. The application of urea as nitrogen source provided greater production of dry matter per cut in black oat culture when compared to ammonium sulfate. The highest efficiencies in the use of nitrogen were obtained by applying 45 kg ha-1 of urea and ammonium sulfate. Black oat culture responds biologically to the nitrogen fertilization dose of 90 kg N ha-1. The applications of 45 kg of N ha-1 in the form of urea and 23 kg ha-1 of ammonium sulfate were economically feasible under the conditions in which the study was carried out.(AU)

Intraspecific tetraploid hybrids of Paspalum notatum: agronomic evaluation of segregating progeny

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.

Intraspecific tetraploid hybrids of Paspalum notatum: agronomic evaluation of segregating progeny

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.(AU)

Forage performance of Paspalum hybrids from an interspecific cross / Desempenho forrageiro de híbridos de Paspalum obtidos por meio de cruzamentos interespecíficos

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.(AU)

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.(AU)