ABSTRACT. The production of maize doubled haploid (DH) lines is a technique commonly used by private companies, but not by Brazilian public institutions. Research on this technique is essential to develop and improve the production of DH lines grown under tropical conditions. We assessed the ability of a gynogenetic haploid inducer system to induce haploids in a tropical environment, assessed the induction rate of haploids identified using the R-navajo morphological marker, checked for interference from the generation of hybrid donors on haploid induction, measured the ability of flow cytometry, and simple sequence repeat marker techniques to identify doubled haploids. Seeds from the inducer Krasnodar Embryo Marker Synthetic (KEMS) line were sown in Ponta Grossa, PR, and Cravinhos, SP, and the plants were crossed to produce six hybrids and their F 2 generations. The seeds were separated according to the R-navajo morphological marker indicator of haploidy (purple endosperm and white embryo) and germinated in a controlled environment. Chromosomal duplication was performed in seedlings selected as putative haploids. We performed subsequent confirmation of ploidy and the success of duplication using flow cytometry and SSR 4231©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (4): 4230-4242 (2013) Production of doubled haploid lines in tropical maize marker techniques. We concluded that DH lines can be obtained from hybrids crossed with the inducer KEMS line. The generation of inbred hybrids did not affect the induction rate or chromosomal duplication in haploids. The use of flow cytometry and SSR markers was effective in verifying chromosomal duplication in haploids.

The predominance of vitreous endosperm in hard texture flint corn (Zea mays L.) can decrease ruminal starch digestion comparatively to the farinaceous endosperm of dent corn, reducing energy content of the grain. The objective of this experiment was to evaluate the effects of texture and maturity stage on ruminal degradability of corn grain. Two dent and two flint hybrids were harvested at the early dent, half milk line, and black layer stages. The proportion of vitreous endosperm (vitreousness) in dent hybrids was 44.3%, while in flint it was 67.0%. There was a linear increase in vitreousness with advancing maturity. Flint hybrids at the early dent stage were more vitreous than dent at the black layer stage. The increase in vitreousness per maturation day was greater for flint hybrids. Grains were incubated in situ in the rumen of 6 cows. The 24-hour ruminal dry matter degradation was 63.3% for dent corn and 52.4% for flint corn. The 72-hour incubation residues of dent and flint hybrids were 7.6% and 15.6%, respectively. Ruminal degradability was similar between hybrids at the early dent and half milk line stages. There was a marked texture effect on ruminal degradability at the black layer stage (quadratic effect of maturity stage and interaction between texture and maturity stage). Use of dent hybrids, compared to flint hybrids, may result in smaller relative reduction in ruminal starch digestion in situations of late grain harvesting. Key words: vitreousness, endosperm, dent corn, flint corn, rumen DEGRADABILIDADE RUMINAL DE GRÃOS DE MILHO DE TEXTURA DURA OU MACIA EM TRÊS ESTÁDIOS DE MATURAÇÃORESUMO: A predominância de endosperma vítreo em milho (Zea mays L.) flint de textura dura pode deprimir a digestão ruminal do amido comparativamente ao endosperma farináceo de milho dentado, reduzindo o conteúdo energético do grão. O objetivo deste experimento foi avaliar os efeitos da textura e do estádio de maturidade sobre a degradabilidade ruminal de grãos de milho. Dois híbridos dentados e dois duros foram colhidos nos estádios dentado inicial, metade da linha do leite e linha preta. A proporção de endosperma vítreo (vitreosidade) dos híbridos dentados foi 44,3% e a dos duros foi 67,0%. Ocorreu aumento linear na vitreosidade com o avançar da maturidade. Os híbridos duros no estádio dentado inicial foram mais vítreos que os dentados no estádio linha preta. O aumento na vitreosidade por dia de maturação foi maior nos híbridos duros. Os grãos foram incubados in situ no rúmen de 6 vacas. A degradação ruminal da matéria seca em 24 horas foi 63,3% nos grãos dentados e 52,4% nos duros. O resíduo após 72 horas de incubação de híbridos dentados e duros foram 7,6% e 15,6%, respectivamente. A degradabilidade ruminal dos híbridos foi similar nos estádios dentado inicial e metade da linha do leite. O efeito da textura sobre a degradabilidade ruminal foi acentuado no estádio linha preta (P < 0,01 para o efeito quadrático de estádio de maturação e para a interação entre textura e estádio de maturação). A utilização de h...

Ciênc. agrotec., Lavras, v. 34, n. 4, p. 953-960, jul./ago., 2010 RESUMOA composição química das sementes pode ser influenciada por fatores genéticos, ambientais e pela disponibilidade de nutrientes no solo durante a produção e, como consequência, terem o seu vigor afetado. O potássio pode influenciar a atividade de várias enzimas presentes nas plantas, necessárias em várias reações envolvidas na utilização de energia, síntese de amido, metabolismo do nitrogênio e respiração. Avaliou-se o efeito da adubação potássica e da calagem na composição química, qualidade fisiológica e na atividade de enzimas de sementes de soja. A pesquisa foi desenvolvida nos laboratórios de análises e biotecnologia de sementes do Departamento de Agricultura e no Laboratório de Produção Vegetal do Departamento de Ciências dos Alimentos da Universidade Federal de Lavras (UFLA). Em sementes de soja do cultivar Msoy 8001, produzidas sob 2 níveis de saturação por base (48% e 85%) e quatro doses de K 2 O por hectare (0, 50, 100 e 200 kg), foram avaliados teores de óleo e proteína, germinação, envelhecimento acelerado e atividade das enzimas envolvidas nos processos de germinação e deterioração de sementes. A adubação potássica não afeta a germinação e o vigor das sementes, enquanto a elevação da saturação por base, proporciona maior vigor de sementes de soja. Há aumento no teor de óleo e redução no teor de proteína em sementes de soja à medida que a dose de K 2 O é aumentada. Ocorre aumento de teor de proteínas em sementes de soja, produzidas sob maiores níveis de saturação por base. A atividade das enzimas piruvato quinase, esterase e álcool desidrogenase em sementes de soja é afetada pela concentração de potássio e saturação por base no solo.Termos para indexação: Nutrientes; sementes, qualidade, composição química. ABSTRACTThe chemical composition of seeds can be influenced by genetical and environmental factors and by the availability of nutrients in the soil during production, which consequently affect their vigor. Potassium can influence the activity of several enzymes present in plants. These enzymes are necessary in a number of reactions involved in the utilization of energy, starch synthesis, nitrogen metabolism and respiration. The effects of potassium fertilization and liming on the chemical composition, physiological quality and enzymes activities of soybean seeds were evaluated. The research was developed in the Seed Analysis Laboratory of the Agriculture Department and in the Plant Production Laboratory in the Food Science Department of the Federal University of Lavras, Lavras (UFLA). In soybean seeds of cultivar Msoy 8001 produced under two levels of base saturation (48% and 85%) and four doses. ha -1 of K 2 O, 0, 50, 100 and 200, oil and protein contents, seed germination, aging test and the activity of some enzymes involved in the seed germination and deterioration processes were evaluated. Seed germination and vigor are not influenced by fertilization with potassium. However, base saturation increases the vigor of soyb...

ABStRACt. The present study compared different similarity and dissimilarity coefficients and their influence in maize inbred line clustering. Ninety maize S 0:1 inbred lines were used and genotyped with 25 microsatellite markers (simple sequence repeat). The simple matching, Rogers and Tanimoto, Russel and Rao, Hamann, Jaccard, SorensenDice, Ochiai, and Roger's modified distance coefficients were compared by consensus index, projection efficiency in a two-dimensional space and by Spearman's correlation. Changes were found in high genetic similarity groupings with different coefficients using the consensus index. Russel and Rao and Jaccard coefficients had the greatest stress values with 75.67 and 40.16%, respectively, indicating that these coefficients should not be used. Genotype ranking changed, mainly in the comparison of the Roger's modified distance in relation to some coefficients (r s = 0.75). Russel and Rao's and Jaccard's coefficients should be avoided for their low accuracy. Moreover, genotype clustering by different similarly coefficients, without a close consideration of these coefficients could affect the research results.

New proposals for models and applications of prediction processes with data on molecular markers may help reduce the financial costs of and identify superior genotypes in maize breeding programs. Studies evaluating Genomic Best Linear Unbiased Prediction (GBLUP) models including dominance effects have not been performed in the univariate and multivariate context in the data analysis of this crop. A single cross hybrid construction procedure was performed in this study using phenotypic data and actual molecular markers of 4,091 maize lines from the public database Panzea. A total of 400 simple hybrids resulting from this process were analyzed using the univariate and multivariate GBLUP model considering only additive effects additive plus dominance effects. Historic heritability scenarios of five traits and other genetic architecture settings were used to compare models, evaluating the predictive ability and estimation of variance components. Marginal differences were detected between the multivariate and univariate models. The main explanation for the small discrepancy between models is the low- to moderate-magnitude correlations between the traits studied and moderate heritabilities. These conditions do not favor the advantages of multivariate analysis. The inclusion of dominance effects in the models was an efficient strategy to improve the predictive ability and estimation quality of variance components.