Jorge Luiz Nedel

Vigor de sementes e análise de crescimento de aveia preta

This study was carried out in Capao do Leao, RS, Brazil, with the objective of evaluating the effect of seed vigor on the growth of two cultivars of cultivated black oats (Avena strigosa Schreb), as well as to verify possible interactions with plant population (150, 300 and 450 pl m-2). Seed vigor and plant population affected dry matter production during the vegetative period. The effects were reduced progressively in the growing season, with no more difference after anthesis. The extreme levels of seed vigor and plant population produced differences in dry matter yield of 410 kg ha-1 and 480 kg ha-1, respectively, at the 75th day after emergence, these effects were due to differences in crop growth rates. A compensatory effect of the plant population on dry matter production was verified, so that the effect of low seed vigor could be compensated by an increase in plant population; the lower the seed vigor level, the greater was the plant population required. High vigor seeds also compensated the effects of low plant populations.

Eficiência de coeficientes de similaridade em genótipos de feijão mediante marcadores RAPD

O objetivo deste trabalho foi avaliar a eficiencia de coeficientes de similaridade em genotipos de feijao por meio de marcadores RAPD. A eficiencia dos coeficientes de similaridade de Jaccard, Sorensen-Dice, Russel e Rao, Ochiai, Coincidencia Simples, Rogers e Tanimoto, Hamann, Kulczynski 2, Yule e Phi no agrupamento de 35 cultivares locais e comerciais de feijao foi analisada com base em 104 marcadores RAPD. Os coeficientes foram comparados por dendrogramas, pela eficiencia da projecao no espaco bidimensional e por grupos formados pelo metodo de otimizacao de Tocher. Os diferentes coeficientes de similaridade apresentaram variacao quanto a eficiencia de projecao no espaco bidimensional e quanto ao numero de grupos formados pelo metodo de otimizacao de Tocher. Os coeficientes de Russel e Rao e de Yule sao os mais discordantes, e os coeficientes de Sorensen-Dice, Ochiai e Kulczynski 2 sao mais eficientes que os demais. O coeficiente de Russel e Rao nao tem a capacidade de agrupar as cultivares em seus respectivos centros de domesticacao.

CONDICIONAMENTO OSMÓTICO EM SEMENTES DE CEBOLA: I. EFEITOS SOBRE A GERMINAÇÃO

Onion seed lots (varieties Aurora and Petrolini) of different vigor levels, were osmoconditioned using aerated aqueous solutions of KNO3 and PEG at 20°C. In addition three soaking times (0, 24 and 48 hours) were evaluated. Following each treatment, seeds were dried in an oven at 30°C until they reached initial moisture levels. Then seeds were divided into two portions. One batch was stored in a dessecador for six months, while the other was immediately evaluated. Results showed that the rate of germination and germination under stress conditions increased in osmoconditioned onion seeds. Treatment with KNO3 for 24 hours presented the best performance. Osmotic conditioning may reverse the process of natural aging of onion seeds. Osmoconditioned onion seeds maintained their physiologic quality up to six months of storage.

Análise de RAPD na identificação de cultivares: uma metodologia útil?

Caracteres morfologicos tem sido utilizados tradicionalmente como assinaturas da identidade e pureza varietal e genetica. Esses descritores se constituem em uma base pobre, por ser uma medida indireta da composicao genetica do material. Uma vez que caracteres moleculares revelam diferencas geneticas mais rapidamente, com maior precisao e sem o obscurecimento causado pelo efeito ambiental, oferecem vantagens significantes em termos de discriminacao, confiabilidade, rapidez e custo reduzido. Um metodo molecular relativamente novo, DNA polimorfico amplificado ao acaso (RAPD), baseado na reacao em cadeia da polimerase (PCR), tem sido adotado por alguns pesquisadores envolvidos no desenvolvimento de metodos de identificacao de cultivares principalmente por ser uma tecnica simples que nao requer nenhuma informacao previa sobre sequencias de nucleotideos do genoma da especie, alem de ser bastante acessivel e de custo relativamente baixo. Mas, infelizmente, a analise de RAPD apresenta serios problemas, principalmente em relacao a reprodutibilidade e caracterizacao da homologia dos produtos. Se esses problemas podem ser efetivamente resolvidos entao a analise de RAPD pode se tornar um metodo eficiente e aplicavel, mas talvez o investimento em tempo e dinheiro seja mais util no desenvolvimento e adaptacao de tecnicas mais promissoras. Ha um grande volume de publicacoes sobre a tecnica de RAPD na literatura, todas evidenciando o mesmo problema: a variabilidade inerente aos produtos de amplificacoes com primers decâmeros limita a sua utilizacao na industria e em programas de certificacao. O objetivo deste trabalho foi discorrer sobre a eficiencia da tecnica de RAPD na identificacao de cultivares, ressaltando as suas vantagens e limitacoes.

Diversidade genética em cultivares locais e comerciais de feijão baseada em marcadores RAPD

Abstract – The objective of this work was to characterize the genetic diversity within and amongcultivars and landraces of common bean from RAPD markers analysis, and to evaluate the capacity ofthis markers in clustering common bean genotypes according to domestication centers and seed color.Thirty five common bean genotypes including 13 commercial cultivars and 22 landraces, from State ofRio Grande do Sul, Brazil, were evaluated. Genetic distances were calculated using Sorensen-Dice’ssimilarity coefficient, displayed in a dendrogram. RAPD markers were efficient in separating cultivarsand landraces according to domestication centers, but not according to seed color. Mesoamericancommercial cultivars and landraces have been clustered in different groups. A high degree of similaritywas observed among cultivars in use in Rio Grande do Sul.Index terms: Phaseolus vulgaris , genetic variation, cluster analysis. (1) Aceito para publicacao em 18 de agosto de 2003.Extraido da tese de doutorado apresentada pelo primeiro autora Universidade Federal de Pelotas (UFPel), Pelotas, RS.

Uso de testes de vigor de sementes na detecção de variabilidade genética intracultivar em pimentão

In order to check the hypothesis of intracultivar polymorphism for vigor in sweetpepper (Capsicum annuum L.), seeds from a single lot of the cultivar Ikeda were submitted to four seed vigor tests, namely: cold test, germination rate index, accelerated aging and seedling vigor classification. Vigorous and less vigorous seedlings were separated by each test and transplanted to a greenhouse where the plants were allowed to produce seeds (S1). As a second step, the seeds from low and high vigor seedlings were resubmitted to the test by which they were originally selected and compared to a check treatment, where selection was not made. Further, only the S1 seeds produced by the plants selected through the cold test were conducted to a second generation in order to verify possible selection gain. After data analysis it was concluded that: a) there are strong evidences indicating individual vigor variation within the seed lot of the cv. Ikeda used; b) the evidences lead to the indication that the variation has, at least, one genetic component which may be used for breeding and seed quality improvement purposes, and c) the cold test was the most efficient for detection of individual vigor difference in the seed population.

Variação e associação de características ligadas a formação do grão de genótipos de trigo

O rendimento de trigo (Triticum aestivum L.) e estabelecido pelo numero de graos produzidos por unidade de area e pelo peso do grao. Este e determinado pela taxa e duracao do desenvolvimento do grao. A taxa e a duracao do enchimento do grao foram determinados em sete genotipos de trigos brasileiros, com o objetivo de avaliar a variacao genotipica para estes caracteres e a relacao dos mesmos com parâmetros agronomicos. Variacoes genotipicas significativas foram observadas, tanto para a taxa como para a duracao de enchimento da grao. A taxa e a duracao de enchimento do grao variaram de 0,077 a 0,089 mg/sem/graus dias acumulados e de 27 a 31 dias, respectivamente. A taxa e nao a duracao de enchimento estava associada ao peso do grao. A selecao de genotipos com maior peso de grao pode levar a obtencao de cultivares de trigo precoces, com maior taxa de enchimento de graos e adequadas a um sistema de duas culturas anuais.

Padrões eletroforéticos de hordeínas e isoenzimas para identificação de cultivares de cevada

The goal of this study was to determine the polyacrylamide gel electrophoretic patterns (electrophoregrams) of the hordeinas and isozymes from five Brazilian barley cultivars: Embrapa 43, Embrapa 127, Embrapa 128, Embrapa 129 e BR 2. The uniformity (homogeneity) of these patterns also was determined through the 90 single seed samples of each cultivar. Most of the cultivars were readily discriminated by hordein electrophoregrams; five barley cultivars presented four different eletroforegrams of hordeins. Three cultivars gave unique hordein patterns, whereas the two others (Embrapa 128 e BR 2) presented different esterases (EC 3.1.1.1) patterns. Jaccard similarity measures of conjugated data of hordeinas and esterases allowed discrimination of all cultivars and biotypes. The cultivar Embrapa 43 showed two biotypes well defined of hordeins and esterases. The variation of the hodeins pattern on that cultivar have direct relation with the variation on zimograms of esterases. This relation was not found in all cultivars that presented biotypes. It was established that electrophoresis data of hordeins and esterases can be helpful on barley cultivars identification.

PADRÕES ELETROFORÉTICOS DE CULTIVARES DE TRIGO INDICADAS PARA REGIÃO SUL DO BRASIL

In Brazil, the methods traditionally used for cultivar identification are morphologic traits from seed, seedling or plant. The methods using electrophoresis allows cultivar identification using less time and resources. The objectives of this study was to define the electrophoretic pattern of wheat cultivars in Southern Brazil, as well as to verify intra-cultivar variation. Four electrophoresis systems were used in polyacrylamide gels. Two were used for total protein (APAGE and SDS-PAGE) and two for the enzymatic systems of esterase and peroxidase. The APAGE allowed to characterize individually the cultivars BR 18, BR 35, CEP 24, CEP 27, EMBRAPA 15, EMBRAPA 40, IAPAR 17, IAPAR 29, OCEPAR 16, OCEPAR 21, RS 01 and RS 08 and put the others in to three groups: group 1: BR 38 and EMBRAPA 52; group 2: EMBRAPA 16, EMBRAPA 24 and EMBRAPA 49; group 3: BR 23, BR 32 and IAPAR 28. With the utilization of SDS-PAGE and esterase it was possible to individualize the cultivars of the three groups. Intra-cultivar variation were not detected using APAGE. However, EMBRAPA 16 showed variation in SDS-PAGE. Using esterase, intra-cultivar variation was detected in BR 38 and EMBRAPA 15; for peroxidase intra-cultivar variation was detected in BR 23, CEP24, CEP 27, EMBRAPA 15, EMBRAPA 40 and IAPAR 17. The results showed that it is possible to identify wheat cultivars by electrophoresis, since the different systems are combined.

Análise numérica dos eletroforegramas de gliadinas de cultivares de triticale

Aiming the automatization of cultivar identification by protein electrophoresis, the objective of this work was evaluate the feasibility of using band intensity values as polimorphism aditional data on cultivar discrimination and compare different similarity coefficients on the analysis of gliadins electophoregrams data. Electrophoregrams of gliadinas take from four cultivars of triticale closely related were compared by the computer-assisted analysis using six binary (presence/absence) coefficients of similarity (Jaccard, Sorensen-Dice, Nei & Li, Simple Matching, Yule and Baroni-Urbani) and five quantitative coefficients (Pearson product moment correlation, Spearman, Percent Similarity, Modified Morisita and Gower). The intensity of bands used on the quantitative analysis of electrophoregrams was distributed in different number of classes of intensity, making possible to evaluate the effect of variability on this parameter. It was used about 60 single seed samples of each cultivar. In spite of low inter-varietal polymorphism, the coefficient means within of the cultivars was always greater than between cultivars. That clearly shows the high discriminating power of the tests. With this study we demonstrate the viability of identifying triticale cultivars by the numeric comparison of gliadin electrophoresis data with a library of electrophoregrams. It allows a more objective comparison of the electrophoregrams, comparing to visual analysis. We also found a great variability on intensity (density) data of bands. The parameter intensity is therefore not much reliable on gliadins polymorphism analysis in triticale. Hence about the intensity, there is a progressive lost on reliability of the results as increase the number of intensity classes.