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Search Results: 1 - 10 of 346528 matches for " Lédo Francisco José da Silva "
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Análise genética em um dialelo de alface
Lédo, Francisco José da Silva;Casali, Vicente Wagner Dias;Cruz, Cosme Dami?o;Lédo, Carlos Alberto da Silva;
Pesquisa Agropecuária Brasileira , 2001, DOI: 10.1590/S0100-204X2001000300013
Abstract: this work aimed to estimate genetic parameters in a lettuce diallel, according to the jinks & hayman's method. the experiment was carried out in a greenhouse, at the universidade federal de vi?osa, from october 20 to december 12, 1996. the experimental design used was a randomized complete blocks, with three replications. pots with 4,5 dm3 of substrate and one plant/pot (plot) were used. six lettuce cultivars and their respective f1 hybrids were evaluated. the following characters were evaluated: fresh matter of aerial part (fmap); dry matter of aerial part (dmap), leaves (dml) and roots (dmr); number of leaves/plant (nul); and stem height (sh). some evidences of epistasis were detected for dmap, nul and sh characters. in fmap the variation of additive nature contributes predominantly to the genetic variability observed between parents and f1. the prevalence of dominance gene effects on the control ofdml and dmr characters were evident. the estimates of genotypic determination coefficient on wide sense () in fmap, dml and dmr were 0.84, 0.85 and 0.90, and restricted sense () 0.66, 0.45 and 0.49.
Análise genética em um dialelo de alface
Lédo Francisco José da Silva,Casali Vicente Wagner Dias,Cruz Cosme Dami?o,Lédo Carlos Alberto da Silva
Pesquisa Agropecuária Brasileira , 2001,
Abstract: Este trabalho teve por objetivo estimar parametros genéticos em um dialelo de alface, segundo o método de Jinks & Hayman. O experimento foi conduzido em casa de vegeta o, na Universidade Federal de Vi osa, no período de 20/10 a 12/12/96. O delineamento experimental adotado foi o de blocos casualizados, com três repeti es. Utilizaram-se vasos com 4,5 dm3 de substrato e uma planta por vaso (parcela). Foram avaliadas seis cultivares de alface (Vitória de Ver o, Nativa, Regina de Ver o, Maravilha de Ver o, Grand Rapids e Mimosa) e seus respectivos híbridos F1. Avaliaram-se os seguintes caracteres: matéria fresca da parte aérea (MFPA); matéria seca da parte aérea (MSPA), folhas (MSF) e raiz (MSR); número de folhas/planta (NUF); e comprimento do caule (CC). Foram detectadas evidências de epistasia nos caracteres MSPA, NUF e CC. Na MFPA a varia o de natureza aditiva contribuiu predominantemente para a variabilidade genética observada entre pais e seus híbridos F1. Evidenciou-se a predominancia de efeitos gênicos de dominancia no controle gênico dos caracteres MSF e MSR. As estimativas do coeficiente de determina o genotípico no sentido amplo () sobre MFPA, MSF e MSR foram de 0,84, 0,85 e 0,90, respectivamente, e restrito () 0,66, 0,45 e 0,49.
Estacionalidade e estabilidade de produ??o de forragem de progênies de Brachiaraia ruziziensis
Souza Sobrinho, Fausto;Lédo, Francisco José da Silva;Kopp, Maurício Marini;
Ciência e Agrotecnologia , 2011, DOI: 10.1590/S1413-70542011000400006
Abstract: the objective of this study was to evaluate the forage biomass productivity of brachiaria ruziziensis progenies and yield stability over different cuts, representing favorable and unfavorable periods of forage development. 118 progenies of b. ruziziensis and the controls b. decumbens cv. basilisk, b. brizantha cv. marandu, b. ruziziensis cv. common and brachiaria sp. were evaluated using a randomized block design with two replicates. there were seven cuts assessment with an average interval of 60 and 90 days in water (5 cuts) and dry (2 cuts) seasons. in each cut, plants height (alt) and dry (pbs) and green (pbv) biomass forage yield were measured. the averages of the different cuts made in dry or water seasons were used to perform statistical analysis in a factorial (progeny x times) for the effects of progeny production seasonality. the stability analysis also was performed. despite the large concentration of pbv and pbs in the rainy season, the existence of genetic variability between progenies of b. ruziziensis for alt, pbv and pbs were observed in both rainy and dry seasons. some evaluated materials showed production stabilities higher than commercial cultivars of brachiaria indicating the possibility of identification and selection of b. ruziziensis material with higher average and stable production over the year.
Repetibilidade de características agron?micas e número de cortes necessários para sele??o de Urochloa ruziziensis
Souza Sobrinho, Fausto;Borges, Vanderley;Lédo, Francisco José da Silva;Kopp, Maurício Marini;
Pesquisa Agropecuária Brasileira , 2010, DOI: 10.1590/S0100-204X2010000600007
Abstract: the objective of this work was to estimate the repeatability of agronomic traits and to determine the appropriate number of cuts for selectig urochloa ruziziensis. one hundred and eighteen progenies of half-sib u. ruziziensis and four checks, the cultivars basilisk (u. decumbens), marandu (u. brizantha), comum (u. ruziziensis) and one access urochloa sp. were evaluated. a randomized complete block with two replications and plots in a 3.0-m line with 1.0x0.5-m spacing was used. seven cuts were made at intervals of 60 and 90 days in wet and dry seasons, respectively. the evaluated characteristics were: plant height, dry matter weight (dm), fresh matter weight (fm) and percentage of dry matter (pdm). the repeatability was estimated by analysis of variance, principal components of the covariance matrix and of the correlation matrix, and structural analysis using the correlation matrix. repeatability estimates varied from 0.31-0.38 for plant height, 0.31-0.43 for fm, 0.16-0.50 for pdm and 0.23-0.43 for dm, with coefficients of determination between 57-87%. the number of cuts necessary to assess the actual value of the characteristics ranged between 7-8 cuts for fm and plant height, and 10-14 for dm and pdm, with coefficients of determination greater than 80%.
Efeito da aduba??o e do calcário na produ??o de matéria seca e de óleo essencial de pimenta-longa
Sousa, Mariangela de Moraes Messias;Lédo, Francisco José da Silva;Pimentel, Flávio Araújo;
Pesquisa Agropecuária Brasileira , 2001, DOI: 10.1590/S0100-204X2001000300002
Abstract: the aim of this paper was to evaluate the effect of different doses of n, p and k, in a soil with and without limestone, on dry matter and essential oil production of long pepper (piper hispidinervum c. dc.). the randomized blocks design was used, with three replications, where the treatments were set up on a 3 x 3 x 3 factorial arrangement, with three doses of n (0, 8 and 16 g/plant of n), p (0, 5 and 10 g/plant of p2o5) and k (0, 5 and 10 g/plant of k2o). at six and twelve months after transplantation, dry matter of branches plus leaves and essential oil total production were evaluated. the p doses improved a quadratic effect on the production of dry matter, with maximum response obtained with 7.1 and 9.6 g/plant of p2o5, on limestoned and non-limestoned soil, respectively. at the non-limestoned soil, the n doses had a quadratic effect on dry matter and essential oil yield, with maximum points of 10.2 and 9.4 g/plant of n, respectively. p was the nutrient that had the most emphasized effect upon the increase of dry matter. average production of dry matter and essential oil were higher in limestoned soil (6,451 kg/ha e 167 l/ha, respectively) than in non-limestoned soil (5,003 kg/ha and 145 l/ha).
Eficiência de inoculantes de rizóbio na nodula??o de alfafa em solo de cerrado
Xavier, Deise Ferreira;Gomes, Fernando Teixeira;Lédo, Francisco José da Silva;Pereira, Ant?nio Vander;
Revista Brasileira de Zootecnia , 2005, DOI: 10.1590/S1516-35982005000300009
Abstract: an experiment was carried out under controlled conditions at the embrapa dairy cattle, juiz de fora, mg, aiming to study the efficiency of two commercial inoculants of rhizobium meliloti on the development of alfalfa cultivars in a ";cerrado"; soil classified as dark-red latossol (oxisol). the experimental design was a randomized blocks, in a 3 x 4 factorial, with four replications and the following treatments: a) three alfalfa cultivars: crioula, crioula cnpgl and p30; b) two commercial inoculants and two checks (with and without nitrogen). sixty days after sowing, a harvest was performed at 5 cm height from ground level, to determine dry matter (dm) weight and total-n in the above ground parts. at ninety days, the whole plants were sampled, to measure the dm yield of both above ground parts and roots, and n content of above ground parts. the presence of nodules in the roots was examined. results of dm yield of above ground parts and roots, and of total-n in the above ground parts, indicated that the two commercial inoculants used were efficient for all the three alfalfa cultivars in the soil, which had its ph corrected. regarding nodulation, the checks with and without nitrogen did not nodulate, indicating that rhizobium meliloti was not present in the soil. these observations reinforce the need of inoculation of alfalfa with appropriate rhizobia in tropical regions.
Associa??o entre caracteres e análise de trilha na sele??o de progênies de meios-irm?os de Brachiaria ruziziensis
Borges, Vanderley;Sobrinho, Fausto Souza;Lédo, Francisco José da Silva;Kopp, Maurício Marini;
Revista Ceres , 2011, DOI: 10.1590/S0034-737X2011000600013
Abstract: high association between fresh and dry mass weight can facilitate early selection of superior genotypes of b. ruziziensis r. germ. & c.m. evrard. the aim of this study was to verify the associations between traits in the selection of b. ruziziensis genotypes. the experiment was arranged in a complete randomized block design with two replications. the traits evaluated were height and vigor of plants; weight of fresh mass and percentage of dry matter of the whole plant, stem and leaf; dry mass weight of total herbage, stem, and leaf and the ratio between productivity of leaf and stem. estimation of simple correlations and path analysis were performed considering the dry mass weight as the main variable. the correlations were mostly low, but significant higher correlations were observed between fresh mass weight and dry mass weight, dry weight of the stem and dry weight of leaves. the path coefficients showed that the direct effects of different explanatory variables on the dry mass weight were mostly low. more significant direct effects were obtained with fresh mass weight, stem dry weight and leaf dry weight, indicating that the fresh mass weight allows for the indirect selection for dry mass weight.
NOTE-Genetic variability in Brachiaria ruziziensis for resistance to spittlebugs
Fausto Souza Sobrinho,Alexander Machado Auad,Francisco José da Silva Lédo
Crop Breeding and Applied Biotechnology , 2010,
Abstract: The aim of this study was to evaluate the resistance of B. ruziziensis clones to the spittlebug species Deoisschach and Mahanarva spectabilis. Together with the cultivar Marandu (B. brizantha) and the progenies 77s, 85s and 106sas controls, 71 B. ruziziensis clones were evaluated in a randomized block design. Six spittlebug eggs about to hatch wereartificially infested and 40 days later evaluated for the percentage of surviving nymphs and plant damage based on a ratingscale. Analysis of variance identified significant differences for nymph survival and plant damage of both spittlebug species.Since nymph survival and damage scores of the clones 100, 95, 19, 42, 93, 4, 92, 47, 26, 63, and 58 were similar to Marandu,these can be considered resistant to insect pests. These results, besides demonstrating the existence of genetic variability fora possible selection, offer hope for an identification of B. ruziziensis spittlebug-resistant genotypes.
Efeito da aduba o e do calcário na produ o de matéria seca e de óleo essencial de pimenta-longa
Sousa Mariangela de Moraes Messias,Lédo Francisco José da Silva,Pimentel Flávio Araújo
Pesquisa Agropecuária Brasileira , 2001,
Abstract: O objetivo deste trabalho foi estudar o efeito de diferentes doses de N, P e K, em solo que recebeu ou n o calcário, sobre a produ o de matéria seca e de óleo essencial de pimenta-longa (Piper hispidinervum C. DC.). Utilizou-se o delineamento experimental de blocos casualizados, com três repeti es. Os tratamentos foram arranjados no esquema fatorial 3 x 3 x 3, com três doses de N (0, 8 e 16 g/planta de N), P (0, 5 e 10 g/planta de P2O5) e K (0, 5 e 10 g/planta de K2O). Aos 6 e 12 meses após o transplantio, foi avaliada a produ o de matéria seca de ramos e folhas, e de óleo essencial. As doses de P promoveram efeito quadrático sobre a produ o de matéria seca, com respostas máximas obtidas com 7,1 e 9,6 g/planta de P2O5, no solo que recebeu ou n o calcário, respectivamente. Em solo n o calcareado, as doses de N promoveram efeito quadrático sobre as produ es de matéria seca e de óleo essencial, com os pontos de máxima de 10,2 e 9,4 g/planta de N, respectivamente. O P foi o nutriente que promoveu efeito mais pronunciado no aumento da produ o de matéria seca. As médias de produ o de matéria seca e de óleo essencial foram maiores no ensaio onde o solo foi calcareado (6.451 kg/ha e 167 L/ha, respectivamente), do que as obtidas no solo n o calcareado (5.003 kg/ha e 145 L/ha, respectivamente).
Effects of nutrient solution pH on growth parameters of alfalfa (Medicago sativa L.) genotypes
Maurício Marini K?pp,Le?nidas Paix?o Passos,Rui da Silva Verneue,Francisco José da Silva Lédo
Comunicata Scientiae , 2011,
Abstract: The effects of nutrient solution pH (4.0, 5.0, 6.0 and 7.0) were examined on growth features of 12 alfalfa genotypes in relation to characters: leaf blade, epicotyl, hypocotyl, first leaf petiole, trifoliate leaf petiole and root fresh weight and epicotyl, hypocotyl, first leaf petiole, trifoliate leaf petiole and root length. Significant quadratic effects of pH solution were detected for all studied parameters. The pH value which resulted in maximum growth varied, according to the studied parameter, between 5.0 and 6.0. The genotypes Victoria, Esmeralda, Crioula and F-708 exhibited superior performance when data were pooled for all studied pH values. The results indicate that the initial growth is affected by pH variation in the nutrient solution, and that contrasting genotypes tend to perform alike.
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