With a demand for high-quality cotton fiber in international markets, improvement of fiber quality in U.S. grown commercial cultivars is necessary. Smith, Hague, Thaxton, and Jones developed a group of experimental lines in 2008 that produced extra-long staple fiber (>35.6 mm). This study determined general combining ability (GCA), and specific combining ability (SCA) of four experimental ELS lines and four commercial cultivars utilizing biplot and conventional diallel analysis, determined performance of F2 progeny, calculated broad-sense (H2) heritability estimates for F2 progeny, and verified the ability of selected parental combinations to produce variable segregating populations with variability of fiber traits. Initial crosses were made in 2007, with additional crosses being made in the field and in a greenhouse in 2008. F1 progeny and parents were grown in a replicated trial near College Station, TX, in 2007 and 2008. F2 progeny lines and parents were grown in replicated trials at two locations in 2008. Due to a significant GxY interaction for all F1 fiber traits, data were reported by years. Experimental ELS lines showed positive GCA effects for fiber length, strength, and length uniformity, while the majority of commercial lines showed negative effects. These findings suggest experimental ELS lines contain alleles for fiber length and strength not present in this particular set of commercial cultivars. Experimental ELS lines exhibited negative GCA effects for lint percent, which suggests further selection is needed for these lines to be commercially competitive. Performances of F2 lines suggest differences in fiber traits are predominantly due to additive gene action. Furthermore, data suggests alleles for fiber length and strength is present in the experimental ELS lines not present in the commercial cultivars. F2 progeny exhibited moderate heritability for all fiber traits. Sufficient variability exists within selected F2 progeny to select for phenotypes exhibiting improved fiber quality over commercial cultivar potential with similar agronomic qualities of commercial cultivars. The ELS lines are a useful source of germplasm for plant breeders looking to improve fiber qualities in their programs.

Submitted by Mateus Olivo null (mateusolivo@hotmail.com) on 2017-07-18T13:56:47Z No. of bitstreams: 1 tese (1).pdf: 2245536 bytes, checksum: 64aa616bea707c6d61006cf0b00b4d6f (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-07-19T17:04:09Z (GMT) No. of bitstreams: 1 olivo_m_dr_bot.pdf: 2245536 bytes, checksum: 64aa616bea707c6d61006cf0b00b4d6f (MD5) / Made available in DSpace on 2017-07-19T17:04:09Z (GMT). No. of bitstreams: 1 olivo_m_dr_bot.pdf: 2245536 bytes, checksum: 64aa616bea707c6d61006cf0b00b4d6f (MD5) Previous issue date: 2017-06-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O cártamo (Carthamus tinctorius L.) membro da família Asteraceae, atualmente é cultivado principalmente como planta oleaginosa. Pode ser utilizado como cultura de inverno em locais de temperaturas amenas e como cultura de primavera em locais de temperaturas mais baixas, apresenta boa adaptação em ambientes de clima mais seco. Atributos que podem torná-lo uma cultura de importante expressão no cerrado brasileiro, local o qual possui um longo período seco com temperaturas elevadas durante o inverno, dificultando o cultivo de outras espécies. Destaca-se como uma cultura estratégica, apresenta boa tolerância a estresse por déficit hídrico em especial no final de ciclo, além de características adequadas para mecanização facilitando o uso dos mesmos equipamentos utilizados nos demais cultivos como soja e milho. O objetivo deste trabalho é realizar um estudo genético para gerar informações aos programas de melhoramento genético. Foram avaliadas 10 combinações em dialelo completo sem recíprocos, em F1 e F2. Na geração F1 foram avaliadas as características de número de capítulos por planta, número de ramos por planta e produção de grãos por planta. Na geração F2 repetiram-se as avaliações realizadas em F1 acrescentando altura de planta, número de grãos por planta, número de grãos por capítulo e percentagem de óleo nos grãos. Após foi determinado a capacidade geral e específica de combinação e análise de correlação simples. As principais conclusões são: Os melhores cruzamento para produção de grãos formam PI537697/PI653152 e PI572450/PI653152 e para teor de óleo formam PI572450/PI572470 e PI572470/PI653152; para todas as características avaliadas em F1 e F2, exceto número de ramos, foi possível observar a contribuição da capacidade geral de combinação na variação genética das populações e para as características altura de planta, produção de grãos por planta, número de grãos por planta, número de grãos por capítulo e percentagem de óleo nos grãos, existe a contribuição da capacidade específica de combinação na variação genética das populações e evidenciando ações gênicas não aditivas e o teor de óleo nos grãos não possui correlação significativa com demais características agronômicas avaliadas. / Safflower (Carthamus tinctorius L.), a member of the Asteraceae family, it is currently cultivated mainly as an oilseed plant. It can be used as a winter crop in mild temperatures and as a spring crop in lower temperature. It is well adapted in drier climates. Attributes that can make it a crop of important expression in the Brazilian “Cerrado Area”, a place that has a long dry period with high temperatures, making difficult the cultivation of other species. In this scenario the safflower is configured as a strategic crop that presents good stress tolerance due to water deficit, especially at the end of the season, besides characteristics suitable for mechanization, using the same equipment already used in other crops as corn and soybeans. The objective of this study is to perform a genetic study to provide information to breeding programs. We evaluated 10 combinations in complete diallel without reciprocal, in F1 and F2. In the F1 generation were evaluated: number of head per plant, number of branches per plant and seed production per plant. In the F2 generation the evaluations performed in F1 were repeated, and added plant height, number of seeds per plant, number of seeds per chapter and percentage of oil in the seeds. After general and specific combining ability were determined, also a simple correlation analysis was performed. The main conclusions are: The best crossing to seed production were PI537697/PI653152 e PI572450/PI653152 and to oil content were PI572450/PI572470 e PI572470/PI653152. For all the characteristics evaluated in F1 and F2, except for number of branches, it was possible to observe the general combining ability contribution in the genetic variation of the populations and for the characteristics plant height, seed production per plant, number of seeds per plant, number of seeds by head and percentage of oil in the seeds, there is the contribution of the specific combining ability in the genetic variation of the populations and showing non-additive gene actions and the oil content in the seeds does not have significant correlation with other evaluated agronomic.

Master of Science / Department of Agronomy / Tesfaye Tesso / Sorghum [Sorghum bicolor (L.) Moench] is listed as one of the potential feedstock sources for biofuel production. While sorghum grain can be fermented into ethanol in a similar way as maize, the greatest potential of the crop is based on its massive biomass and sugar rich juices. Thus development of the crop as alternative energy source requires improvement of these traits. The objectives of this study were (1) to determine the mode of inheritance of traits related to ethanol production and identify suitable genetic sources for use in breeding programs, and (2) to evaluate the potential of low lignin mutations for biomass feedstock production and assess biotic stress risks associated with deployment of the mutations. The study consisted of three related experiments: (i) estimating the combining ability of selected sweet and high biomass sorghum genotypes for biofuel traits and resistance to stalk lodging, (ii) determine the impact of brown mid-rib mutations on biofuel production and their reaction to infection by Macrophomina phaseolina and Fusarium thapsinum, and (iii) assess the reaction of low lignin mutants to green bug feeding. In the first experiment six sorghum genotypes of variable characteristics (PI193073, PI257602, PI185672, PI195754, SC382 and SC373) were crossed to three standard seed parent lines ATx3042, ATx623 and ATx399. The resulting hybrids and the parents were evaluated at four locations, three replications during 2009 and 2010 seasons. Data were collected on phenology, plant height, juice yield, °brix score and biomass production. In the second experiment, two brown mid-rib mutations (bmr6 and bmr12) and their normal versions were studied in four forage sorghum backgrounds (Atlas, Early Hegari, Kansas Collier and Rox Orange). The experiment was planted in four replications and at 14 d after flowering five plants in a plot were artificially infected with F. thapsinum and another five with M. phaseolina. The plants were harvested and rated for disease severity (lesion length and nodes crossed). Another five normal plants in each plot were harvested and used to determine biofuel traits (juice yield, ºbrix score and biomass). In the third experiment, a subset of entries evaluated in experiment II and three tolerant and susceptible checks were tested for greenbug feeding damage. Biotype K greenbug colony was inoculated to each genotype using double sticky foam cages. Feeding damage was assessed as percent chlorophyll loss using SPAD meter. There was significant general combining ability (GCA) effect among the male entries for juice yield, stem obrix and biomass production indicating that these traits are controlled by additive genes. Lines PI257602 and PI185672 in particular, had the highest GCA for all the traits and should serve as excellent breeding materials. There was no significant difference among the bmr mutants and between the bmr and normal genotypes for both stalk rot and greenbug damage. In conclusion, juice yield, °brix and biomass are largely controlled by additive genes and hence are amenable to genetic manipulation. The bmr mutations despite their impact on lignin content do not increase risk of attack by stalk rot pathogens and greenbugs and thus can be deployed for biofuel production without incurring losses to these factors.

Quality Protein Maize (QPM) with the mutant gene opaque-2 (o2), has higher lysine and tryptophan content and hard endosperm which is less susceptible to mechanical and biological damage. Three experiments were conducted to characterize the phenotypic and genotypic characteristics of high lysine maize. In the first experiment two separate diallels including 7 white and 9 yellow QPM inbreds were evaluated in five southern USA environments to estimate the general (GCA) and specific combining abilities (SCA) for grain yield and to identify potential heterotic relationships among them. QPM hybrids yielded less than commercial checks. GCA effects across environments were non-significant for grain yield but highly significant for secondary traits. Best yielding hybrids resulted from crosses among inbreds from different programs (CIMMYT, Mexico; University of Natal, South Africa and TAMU, USA). In the second experiment testcrosses between QPM inbreds and Tx804, were evaluated for agronomic performance, aflatoxin resistance and quality. QPM inbreds in testcrosses have similar flowering dates, plant height, ear height and test weights but lower grain yield than normal checks. Population 69 inbreds and their testcrosses were least susceptible to aflatoxin. Aflatoxin in testcrosses was positively correlated with endosperm texture (0.67) and kernel integrity (0.60) but negatively correlated with grain yield (-0.30) and silking date (-0.50). Tryptophan content was negatively correlated with endosperm modification. Amino acid levels of inbred lines were significantly correlated with those of hybrids, but with low predictive value. In the third experiment 92 high lysine maize inbreds with different origins [Stiff Stalk, Non Stiff Stalk, Pop 69, temperate (Tx802, Tx804, Tx806, B97, B104) and exotic subtropical lines (CML161, Do940y and Ko326y)] were haplotyped on a cM scale utilizing 43 mapped SSR markers to characterize genetic diversity on chromosome 7, estimate linkage disequilibrium around opaque-2 locus and determine the parental contribution in some inbreds. Dendrograms of genetic similarity showed clusters in agreement with the different origin of inbreds. A total of 200 alleles were detected with an average of 4.7 alleles/locus. Significant linkage disequilibrium was detected around opaque-2 locus. Parental contributions of haplotypes showed segments of chromosome 7 exclusively contributed by one or the other parent.

Made available in DSpace on 2014-06-11T19:30:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T20:00:36Z : No. of bitstreams: 1 lima_mwp_dr_botfca.pdf: 347050 bytes, checksum: 56204ce7428a20502b79ab1119ebfc3f (MD5) / Com a crescente demanda de milho doce no mercado brasileiro para diversas finalidades, torna-se necessário o desenvolvimento de materiais cada vez mais produtivos. Neste contexto, esse trabalho objetivou avaliar as capacidades geral e específica de combinação de linhagens endogâmicas de milho doce, portadoras do gene SHRUNKEN-2, bem como, identificar híbridos simples promissores para utilização como enlatados e/ou comercialização de espigas na forma de milho verde. Para isso, foram obtidos híbridos simples por meio de cruzamentos dialélicos parciais incompletos. As avaliações deram-se no ano agrícola 2000/2001 em São Manuel-SP, Piracanjuba-GO e Bragança Paulista-SP. Foram conduzidos 4 experimentos por local, utilizando o delineamento em blocos casualizados no esquema de látice simples 10 x 10, onde as parcelas constituíram-se de 1 linha de 5 metros. A partir dos dados de produção total de espigas com palha, produção comercial com palha, produção comercial sem palha, alturas de planta e de espiga e índice de espigas dos híbridos, foram obtidas as estimativas dos parâmetros genéticos, utilizando-se o método dos quadrados mínimos. Após o desdobramento do quadrado médio dos tratamentos em capacidades geral do grupo 1, do grupo 2 e da capacidade específica de combinação, constatou-se maior variabilidade por parte da capacidade geral de combinação do grupo 2 de genitores; o efeito gênico predominante foi o de origem não aditiva; ocorrência de genitores com boa capacidade combinatória; existência de híbridos promissores para cada local de avaliação. / With the crescent demand of swet corn in the Brazilian market for distinct purposes, it becomes necessary the development of materials more and more productives. In this context, this research objected to evaluate the general and specific combining abilities of sweet corn inbred lines with SHRUNKEN – 2 gene, as well as identify single-crosses promissing to utilization like canned and/ or commercialization of ears as green corn. For that, it was obtained single-crosses by using of partial diallel incomplete crosses. The evaluations were done in 2000 / 2001 in São Manuel – SP, Piracanjuba – GO e Bragança Paulista – SP, Brazil. It was carried out four experiments per place by utilizing the 10 x 10 simple lattice design, where the plots consisted in one line of five meters. From the basis of total production of ear with husk, commercial production with husk, commercial production without husk, plant heigh and ear, and the index of ear from single cross, was obtained by estimation of minimum square. Afterwards the unrolled of the mean square of the treatments in general combining ability of group 1 and group 2, and of the specific combining ability evidencied a large variability apart of general combining ability of the group 2 parentals; the predominant gene ffect was non- additive; occurence of parentals with a good combining ability; and the existence of promissing single crosses for each evaluated place.

Orientador: João Antonio da Costa Andrade / Banca: Mario Luiz Teixeira de Moraes / Banca: José Roberto Môro / Resumo: O sucesso nos programas de melhoramento genético de milho depende da identificação de parentais com boa capacidade de combinação para a produção de híbridos. O objetivo deste trabalho foi identificar linhagens com boa capacidade de combinação utilizando dialelo parcial. Foram avaliadas 16 linhagens, das populações de milho Dentado e Flintisa, em um dialelo parcial onde cada linhagem foi cruzada com as oito linhagens da população contrastante, obtendo-se 64 híbridos simples. Os 64 híbridos foram avaliados em látice triplo em duas safras (semeaduras em 04/07/2009 e 16/11/2009). Ao final de cada repetição do látice foram colocadas as testemunhas comerciais XB 6012, AG 9010, XB 7253 e BG 7049, visando uma comparação simples com os híbridos experimentais. Foram preditos híbridos duplos e triplos. Os caracteres mensurados foram florescimento feminino, altura de plantas, altura de espigas, acamamento e rendimento de grãos. Os híbridos simples 4Dx6F, 7Dx4F, 7Dx6F e 7Dx8F foram indicados para prosseguirem no programa como promissores para as duas safras. Os híbridos simples 1Dx6F, 2Dx8F, 5Dx5F, 7Dx1F, e 7Dx3F foram indicados para prosseguirem no programa como promissores para a primeira safra. Os híbridos simples 3Dx2F, 3Dx3F, 2Dx7F, 5Dx6F, 6Dx3F, 7Dx4F, 2Dx5F, 2Dx6F, 7Dx2F e 7Dx3F foram indicados para prosseguirem no programa como promissores para a segunda safra. Os híbridos triplos mais promissores para a primeira safra de semeadura ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The success in the maize breeding programs depends of the identification of inbred lines with good combining ability for hybrids production. The objective of this study was to identify inbred lines with good combining ability using partial diallel. Were evaluated 16 inbred lines of the maize populations Dentado and Flintisa in a partial diallel where each inbred line was crossed with the eight of the other population, resulting in 64 hybrids. The 64 hybrids were evaluated in a triple lattice in two crop season (sowing on 04/07/2009 and 16/11/2009). At the end of each repetition of the lattice were placed commercial controls XB 6012, AG 9010, XB 7253 and BG 7049, seeking a simple comparison with the experimental hybrids. Were measured the female flowering, plant height, ear height, lodging and grain yield. The hybrids 4Dx6F, 7Dx4F, 7Dx8F and 7Dx8F were appointed to continue in program as promising for the two crop seasons. The hybrids 1Dx6F, 2Dx8F, 5Dx5F, 7Dx1F, e 7Dx3F were appointed to continue in program as promising for the first crop season. The hybrids 3Dx2F, 3Dx3F, 2Dx7F, 5Dx6F, 6Dx3F, 7Dx4F, 2Dx5F, 2Dx6F, 7Dx2F e 7Dx3F were appointed to continue the program as promising for the second crop season. The most promising triple hybrids for the first crop can be obtained as follows: Simple hybrid parental involving inbred lines 1F, 3F, 4F and 8F, with the inbred line 7D; simple hybrid parental involving inbred lines 1D, 2D and 4D, with the inbred line 6F; simple hybrid parental involving inbred lines 3D and 5D, with the inbred line 5F. The triple hybrids more promising for the second crop planting can be obtained as follows: Simple hybrid parental involving inbred lines 3D and 6D, with the inbred line 3F; simple hybrid parental involving inbred lines 4D, 5D and 7D, with the inbred line 6F; simple hybrid parental involving inbred lines 3D and 5D, with the inbred line 2F; simple ... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:29:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-01Bitstream added on 2014-06-13T20:19:52Z : No. of bitstreams: 1 goncalves_kcg_me_ilha.pdf: 342441 bytes, checksum: 4b60e62be3998eef5ca1f73779af4cbb (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O sucesso nos programas de melhoramento genético de milho depende da identificação de parentais com boa capacidade de combinação para a produção de híbridos. O objetivo deste trabalho foi identificar linhagens com boa capacidade de combinação utilizando dialelo parcial. Foram avaliadas 16 linhagens, das populações de milho Dentado e Flintisa, em um dialelo parcial onde cada linhagem foi cruzada com as oito linhagens da população contrastante, obtendo-se 64 híbridos simples. Os 64 híbridos foram avaliados em látice triplo em duas safras (semeaduras em 04/07/2009 e 16/11/2009). Ao final de cada repetição do látice foram colocadas as testemunhas comerciais XB 6012, AG 9010, XB 7253 e BG 7049, visando uma comparação simples com os híbridos experimentais. Foram preditos híbridos duplos e triplos. Os caracteres mensurados foram florescimento feminino, altura de plantas, altura de espigas, acamamento e rendimento de grãos. Os híbridos simples 4Dx6F, 7Dx4F, 7Dx6F e 7Dx8F foram indicados para prosseguirem no programa como promissores para as duas safras. Os híbridos simples 1Dx6F, 2Dx8F, 5Dx5F, 7Dx1F, e 7Dx3F foram indicados para prosseguirem no programa como promissores para a primeira safra. Os híbridos simples 3Dx2F, 3Dx3F, 2Dx7F, 5Dx6F, 6Dx3F, 7Dx4F, 2Dx5F, 2Dx6F, 7Dx2F e 7Dx3F foram indicados para prosseguirem no programa como promissores para a segunda safra. Os híbridos triplos mais promissores para a primeira safra de semeadura... / The success in the maize breeding programs depends of the identification of inbred lines with good combining ability for hybrids production. The objective of this study was to identify inbred lines with good combining ability using partial diallel. Were evaluated 16 inbred lines of the maize populations Dentado and Flintisa in a partial diallel where each inbred line was crossed with the eight of the other population, resulting in 64 hybrids. The 64 hybrids were evaluated in a triple lattice in two crop season (sowing on 04/07/2009 and 16/11/2009). At the end of each repetition of the lattice were placed commercial controls XB 6012, AG 9010, XB 7253 and BG 7049, seeking a simple comparison with the experimental hybrids. Were measured the female flowering, plant height, ear height, lodging and grain yield. The hybrids 4Dx6F, 7Dx4F, 7Dx8F and 7Dx8F were appointed to continue in program as promising for the two crop seasons. The hybrids 1Dx6F, 2Dx8F, 5Dx5F, 7Dx1F, e 7Dx3F were appointed to continue in program as promising for the first crop season. The hybrids 3Dx2F, 3Dx3F, 2Dx7F, 5Dx6F, 6Dx3F, 7Dx4F, 2Dx5F, 2Dx6F, 7Dx2F e 7Dx3F were appointed to continue the program as promising for the second crop season. The most promising triple hybrids for the first crop can be obtained as follows: Simple hybrid parental involving inbred lines 1F, 3F, 4F and 8F, with the inbred line 7D; simple hybrid parental involving inbred lines 1D, 2D and 4D, with the inbred line 6F; simple hybrid parental involving inbred lines 3D and 5D, with the inbred line 5F. The triple hybrids more promising for the second crop planting can be obtained as follows: Simple hybrid parental involving inbred lines 3D and 6D, with the inbred line 3F; simple hybrid parental involving inbred lines 4D, 5D and 7D, with the inbred line 6F; simple hybrid parental involving inbred lines 3D and 5D, with the inbred line 2F; simple ... (Complete abstract click electronic access below)

A informação sobre o tipo de herança de um caráter considerado para fins de seleção é de extrema importância para o sucesso dos programas de melhoramento. O caráter senescência retardada, usualmente chamado de stay-green, tem sido relacionado em diversas culturas à tolerância a estresses abióticos, principalmente ao estresse devido à seca. Embora a maioria dos híbridos de milho comerciais sejam stay-green, as informações sobre o seu tipo de herança são muito limitadas. Assim, este trabalho teve como objetivo estudar a herança do caráter stay-green em milho tropical. O material genético utilizado incluiu 55 linhagens de diversas origens, a fim de representar a variabilidade genética em milho tropical. Foram realizados cruzamentos dialélicos parciais, onde 50 linhagens foram cruzadas com outras 5 linhagens utilizadas como testadoras, originando 250 cruzamentos. Os 250 cruzamentos e seis híbridos comerciais foram avaliados em 8 ambientes no delineamento de látice simples 16x16 com duas repetições. O caráter stay-green foi avaliado em cinco plantas competitivas por parcela, 120 dias após a semeadura, através de uma escala de notas visual de 1 a 5, onde a nota 1 se referia às plantas verdes e a nota 5 às plantas secas. Foi necessário tomar dados de florescimento feminino para utilizá-los como covariável nas análises estatísticas e corrigir as diferenças de maturação entre os cruzamentos. A análise de variância dialélica foi realizada de acordo com o método 4 do modelo 1 de Griffing (1956), adaptado para dialelos parciais em múltiplos ambientes. A capacidade geral de combinação (CGC), tanto para as linhagens como para os testadores, e a capacidade específica de combinação (CEC) foram altamente significativas )01,0(<=P, mostrando que tanto a CGC como a CEC contribuíram significativamente para a expressão do caráter. Porém a contribuição da CGC foi de 69,06% e a da CEC foi de 30,94% para a variação entre cruzamentos, indicando que os efeitos aditivos, relacionados à CGC, são mais importantes que os efeitos não aditivos (dominância e epistasia), que são relacionados à CEC, na variação dos cruzamentos. Tanto a CGC como a CEC interagiram significativamente com o ambiente, evidenciando que estes parâmetros não são consistentes nos diversos ambientes. Então, a seleção para o caráter stay-green deve ser baseada em médias de experimentos avaliados com repetições em diversos ambientes. / Information on the inheritance of traits to be selected is of paramount importance for the success of breeding programs. The trait delayed senescence, usually named \"stay-green\" trait, has been related to tolerance to abiotic stresses, mainly drought stress, in several crop species. Although the majority of commercial maize hybrids are \"stay-green\", limited information are available on its inheritance. Thus, this research was conducted to study the inheritance of the stay-green trait in tropical maize. The genetic material included 55 inbred lines from several sources to represent the genetic variation of tropical maize. Fifty inbred lines were crossed to 05 inbreds as testers following the partial diallel cross design, giving rise to 250 single crosses. The crosses and six commercial hybrids, 256 entries, were evaluated at eight environments using a 16 x 16 lattice design with two replications per environment. The stay-green trait was recorded 120 days after sowing, in five competitive plants per plot, following a visual note scale, i.e., from 1 to 5, where 1 refers to green plants and 5 to no-green plants. Also, the trait days to mid-silking was recorded and used as covariate to correct for differences of maturing among crosses. The analysis of variance of the diallel crosses was computed following the method 4 model 1 of Griffing (1956) extended to multiple environments. The general combining ability (GCA) for both the inbreds and the testers, and the specific combining ability (SCA) were all highly significant (P<=0.01), showing that GCA as well as SCA contribute significantly for the expression of the trait. However, the contribution of the GCA was 69.06% and of the SCA was 30.94% for the variation among the crosses, indicating that the additive effects, which are related to GCA, are more important than the non-additive effects (dominance and epistasis), which are related to SCA, for the variation of the crosses. Both GCA and SCA interacted significantly with the environments, showing that these parameters were not consistent across the environments. Thus, selection for the stay-green trait should be based on the means of experiments evaluated in several environments.

Made available in DSpace on 2014-08-20T13:25:37Z (GMT). No. of bitstreams: 1 dissertacao_rafael_nornberg.pdf: 1775290 bytes, checksum: 1aed782bae5be322b9bc4cec8e20ade0 (MD5) Previous issue date: 2012-03-13 / The climate adversities, such as high temperatures and rain before and during the harvesting period lead to a phenomenon called Pre-harvest sprouting (PHS) of wheat grain. This germination decreases the wheat flour quality through the activation of enzymes responsible for germination which degrade starch. Therefore, this study had as objective to analyse the character pre-harvest sprouting in hexaploid wheat genotypes (Triticum aestivum L.), in the Southern region of Brazil, based on distinct evaluation years. Also, the evaluations aim to indicate the most adapted cultivars for Southern Brazil and to select parental genotypes for breeding programs of wheat. The experiment was conducted in the years 2010 and 2011, in the Centro de Genômica e Fitomelhoramento, Faculdade de Agronomia Eliseu Maciel, Universidade Federal de Pelotas (CGF/FAEM/UFPel), located at Capão do Leão County/RS, Brazil. The design used was random blocks with three replications. A total of 33 genotypes were phenotyped regarding agronomic and pre-harvest sprouting characters in wheat. Simultaneously, in 2010, 56 F1 and F2 hybrid populations obtained from artificial hybridizations between eight wheat cultivars, with different tolerance to sprouting according to a complete diallel design, with reciprocals. The populations and their parental genotypes were evaluated in the agricultural season of 2011. In this experiment, the following characters were evaluated: percentage of germinated grains (GG) in the fixed generations F1 and parents, falling number index (FNI) in the fixed generations F1 and parents, and segregant populations (F2). In the analysis of genotype x year, it was detected an interference of the environment on the results of some genotypes. The genotypes: BIO 08228, RAÍZES, HORIZONTE and BRS 194 with the lowest GG values, and the cultivar GUAMIRIM with high FNI, for both evaluation years, showing the presence of PHS tolerance alleles. Based on the genetic dissimilarity, was obtained from the prediction of important parents. Thus elite genotypes such as TBIO ITAIPÚ, BIO 08228, RAÍZES, HORIZONTE, BRS 194, TBIO PIONEIRO, BIO 07367, RAÍZES, GUAMIRIM and FRONTANA were obtained to form the crossing blocks, aiming to complement the distinct alleles for PHS. The majority of genotypes presented reduced alpha-amylase activity, which causes starch degradation. The genotypes TBIO PIONEIRO, MARFIM and TBIO TIBAGI, on the other hand, presented the lowest alpha-amylase activity. There was a high heritability for both characters in both years except for GG of susceptible genotypes in 2011. The PHS tolerance is controlled by additive effects of genes evidenced by high general combining ability and by non-additive effects of genes evidenced by the specific combining ability, but it was evident that the additive effects were more important. The cultivars QUARTZO and FRONTANA presented the best potential for the use in crossing blocks aiming to increase PHS tolerance and to reduce alpha-amylase activity. Transgressive segregation was observed with high heterosis estimates for both traits FNI and GG. This, added to the loss of vigor by inbreeding for FNI, this indicates that these combinations are potential sources of tolerance to PHS. There was a high reciprocal effect that should be taken into account when producing hybrid cultivars with tolerance to pre-harvest germination and high FNI. / As adversidades climáticas como temperaturas elevadas e precipitação antes e durante o período de colheita ocasionam o fenômeno da germinação na pré-colheita (Pre-harvest sprouting PHS) dos grãos de trigo. Tal condução deprecia a qualidade da farinha por meio da atividade de enzimas responsáveis pela germinação, que degradam o amido. Desta forma, o estudo teve o objetivo de analisar o comportamento do caráter germinação na pré-colheita em genótipos de trigo hexaplóide (Triticum aestivum L.), com base em distintos anos de avaliação, gerando informação para a melhor indicação de cultivares a região sul do Brasil e na reposição de combinações promissoras em blocos de cruzamentos em programas de melhoramento genético do trigo. O experimento foi conduzido nos anos de 2010 e 2011, no Centro de Genômica e Fitomelhoramento, Faculdade de Agronomia Eliseu Maciel, Universidade Federal de Pelotas (CGF/FAEM/UFPel), situado no município do Capão do Leão/RS, Brasil. O delineamento empregado foi de blocos ao acaso com três repetições, foram analisados 33 genótipos de trigo a partir de caracteres agronômicos e relacionados a germinação na pré-colheita do trigo. Simultaneamente, no ano de 2010 foram obtidas 56 populações híbridas F1 e F2 a partir de hibridações artificiais entre oito cultivares de trigo, com distinta tolerância a germinação na espiga, seguindo o delineamento dialélico completo, com os recíprocos. As populações e os respectivos genitores foram avaliados na safra agrícola de 2011 em campo experimental, no município de Capão do Leão, adotando o delineamento em blocos ao acaso, com três repetições. Neste experimento foram avaliados os caracteres: percentual de grãos germinados (GG) nas gerações fixas F1 e genitores, e índice de queda úmido (IQU), nas gerações fixas (F1 e genitores) e populações segregantes (F2). Na análise de interação genótipo x ano foi detectada interferência do ambiente sobre alguns genótipos. Os genótipos BIO 08228, RAÍZES, HORIZONTE e BRS 194 foram aqueles de menores valores de GG, e a cultivar GUAMIRIM com elevado IQ, para os dois anos de avaliação, demonstrando a presença de genes de tolerância a PHS. Com base nos resultados da dissimilaridade genética, foi obtida a predição de importantes genitores. Assim destacam-se TBIO ITAIPÚ, BIO 08228, RAÍZES, HORIZONTE, BRS 194, TBIO PIONEIRO, BIO 07367, RAÍZES, GUAMIRIM e FRONTANA para compor os blocos de cruzamento, visando à melhor complementaridade de alelos distintos de tolerância a PHS em trigo. No desempenho per se, a maioria dos genótipos apresentaram reduzida atividade de alfa-amilase que degradam o amido. Os genótipos TBIO PIONEIRO, MARFIM e TBIO TIBAGI, expressaram reduzida atividade da enzima alfa-amilase. Houve pronunciada herdabilidades para os caracteres em ambos os anos exceto para GG nos genótipos sensíveis em 2011. A tolerância a PHS é controlada por genes de efeitos aditivos evidenciados por elevadas capacidade geral de combinação (CGC) e por genes de efeitos não aditivos evidenciado pela capacidade especifica de combinação (CEC).Se destaca que os efeitos aditivos foram mais importantes sobre a variância genética total. Neste experimento, as cultivares QUARTZO e FRONTANA apresentam o melhor potencial para o uso em blocos de cruzamentos para incremento da tolerância a PHS e redução da atividade da enzima alfa-amilase. Foram evidenciadas constituições genéticas transgressivas em F2 associadas com elevadas estimativas de heterose em F1 para ambas as características avaliadas no IQU e GG. Isto, conciliado a baixa perda de vigor por endogamia para IQU, evidenciando que as populações destas combinações são potenciais fontes de recuperação de indivíduos superiores. Existe pronunciado efeito recíproco para o caráter tolerância a germinação na pré-colheita e aumento do índice de queda.

Made available in DSpace on 2014-08-20T13:25:40Z (GMT). No. of bitstreams: 1 tese_douglas_andre_mallmann_schmidt.pdf: 939381 bytes, checksum: c4159f7fe0e529065ea06d662c6b59a8 (MD5) Previous issue date: 2008-07-28 / In plant breeding programs, parental selection is a very important step. The selection of parents to be used to obtain the segregating populations can determine the success or failure in achieving genetic gains. Diallel analysis has been used to determine the general and specific combining ability and to aid the selection of the most promising combinations. The fitting of genotypes to environmental conditions that allow the expression of full genetic potential for the target characters, has shown great importance to maximize wheat grain yield and quality. In this sense, the main objective of the study was to determine the combining ability of wheat genotypes, and their performance for grain yield components and industrial quality traits in different environments under different nitrogen levels. Six parents were employed in diallel analysis, including reciprocal crosses, to evaluate general and specific combining ability of agronomic traits. The diallel cross experiments were conducted in Capão do Leão County/RS in 2007 and the experiment evaluating nitrogen levels was conducted in environments of Capão do Leão County in 2006 and 2007, and Ijuí County in 2007, both located in Rio Grande do Sul State. The nitrogen doses used were 0, 40, 80 and 120 kg ha-1 as cover fertilizer. The mean squares for general combining ability were greater than those for specific combining ability for the characters number of grains per ear, grain weight, number of ears per plant and grain yield per plant. Additive gene action was likely to more intensely affect these characters. It was possible to verify effects of heterosis, mostly for the character grain yield per plant with results above 100% of mean heterosis. The high heterosis values in F1, when associated with high advanced generation bulk yields in, increases the likelihood of obtaining high yielding genotypes by the increase of recombinant genotypic classes. Maternal and extrachromosomal effects were very intense, suggesting that breeding programs should pay attention to which parent is used as pollen donor and vice-versa. Different responses to nitrogen fertilization were observed regarding grain yield. The nitrogen fertilization promoted increases in the rates of lodging in all genotypes tested in the three environments. In environments with high yield potential, the increase in the level of nitrogen, did not increase gluten strength. Bread wheat genotypes better respond to nitrogen availability increases. On the other hand, genotypes with low gluten strength did not respond to nitrogen increases. / Em programas de melhoramento genético vegetal, a escolha de genitores tem sido uma das etapas de maior importância. Esta etapa determina os genitores que serão empregados para obtenção das populações segregantes, e pode promover o sucesso ou insucesso na obtenção do progresso genético. A análise dialélica tem sido empregada para determinar a capacidade geral e específica de combinação dos genitores, auxiliando o melhorista na escolha das combinações mais promissoras. O ajuste dos genótipos às condições de ambiente, que proporcionem a expressão do potencial genético, tem revelado grande importância para a maximização do rendimento e qualidade de grãos. Neste sentido, o objetivo do trabalho foi verificar a capacidade combinatória de genótipos de trigo, o seu desempenho para os componentes do rendimento de grãos e qualidade industrial, em distintos ambientes sob níveis de disponibilização de nitrogênio. Foram empregados seis genitores na análise dialélica, considerando os recíprocos, para avaliar a capacidade geral e específica de combinação, heterose e efeitos recíprocos, de caracteres de importância agronômica. O experimento do cruzamento dialélico foi conduzido em Capão do Leão/RS no ano agrícola de 2007, enquanto que o experimento de adubação nitrogenada foi conduzido nos ambientes de Capão do Leão/RS em 2006 e 2007, e Ijuí/RS em 2007, utilizando doses de 0, 40, 80 e 120 kg ha-1 de nitrogênio em cobertura. A magnitude dos quadrados médios da capacidade geral de combinação foi maior do que a capacidade específica de combinação, para os caracteres número de grãos por espiga, massa média de grãos, número de espigas por planta e produção de grãos por planta, evidenciando a provável contribuição mais intensa da ação gênica aditiva no controle destes caracteres. Foi possível verificar efeitos de heterose, principalmente para o caráter produção de grãos por planta, com resultados superiores a 100% de heterose média em relação aos genitores. A elevada heterose expressa na geração F1, quando associada a rendimentos de grãos com bulks em geração avançadas, promove maior probabilidade de obtenção de genótipos superiores, devido a maior freqüência de genes complementares dominantes na progênie. Os efeitos determinados por herança extracromossômica ou efeito materno foram intensos, revelando provável incremento na eficiência de programas de melhoramento, pelos benefícios proporcionados com o controle dos genitores, utilizados como doadores ou receptores de pólen em cruzamentos de trigo. A adubação nitrogenada determinou comportamento diferenciado dos genótipos, quanto ao provável incremento do rendimento de grãos. A suplementação de nitrogênio promoveu incrementos nos índices de acamamento, em todos os genótipos nos três ambientes testados. Em ambientes com alto potencial produtivo, o incremento no nível de nitrogênio, não promoveu aumento expressivo na força geral de glúten. Genótipos classificados como trigo pão, respondem mais intensamente para maior da força geral de glúten ao incremento da disponibilidade de nitrogênio, enquanto que genótipos classificados como brandos, não revelam aumentos expressivos para força geral de glúten, a maior disponibilidade do nutriente.