Diversas pesquisas têm reportado que o aumento da produtividade da cultura do milho se deve muito mais à tolerância a estresses abióticos do que a aumentos per se. O déficit hídrico é um dos mais importantes fatores envolvidos na redução de produtividade nessa cultura, mas devido à dificuldade de seleção direta para tolerância à seca, são empregados caracteres secundários como o caráter stay green ou senescência retardada de folhas e colmos. Todavia, estudos sobre a herança desse caráter são escassos na literatura. Em vista disso, este trabalho teve como objetivo estudar a herança deste caráter em milho tropical, utilizando o delineamento III (Comstock e Robinson, 1952). A partir do cruzamento entre as linhagens endogâmicas L08-05F e L38-05D, foram obtidas 100 progênies F2:3, as quais foram retrocruzadas com cada um dos parentais, resultando em 200 progênies de retrocruzamento. Estas progênies foram avaliadas em dez ambientes, com duas repetições por ambiente, em Piracicaba SP, utilizando o delineamento ?-látice. A avaliação do stay green foi feita em dez plantas competitivas por parcela, 120 dias após a semeadura, utilizando uma escala de notas variando de 1 a 5, em que 1 correspondeu às plantas com todas as folhas acima e pelo menos duas folhas verdes abaixo da espiga e 5 à planta com todas as folhas secas. O caráter florescimento feminino foi avaliado e utilizado como covariável para ajuste das variações de maturação das progênies, e as médias das parcelas foram utilizadas para as análises. A estimativa da variância aditiva foi muito superior à de dominância e a variância da interação aditiva por ambiente apresentou maior magnitude que a variância aditiva. O tipo de ação gênica foi de dominância parcial, mas devido ao desequilíbrio de ligação da população, este pode estar superestimado. O coeficiente de herdabilidade em nível de plantas apresentou baixa magnitude (~25%) enquanto que em nível de médias a magnitude foi elevada (~70%). Estes resultados indicam que os efeitos aditivos são mais importantes que os dominantes no controle do caráter stay green e que os efeitos aditivos não são consistentes nos diversos ambientes de avaliação. Assim, o nível de heterose deve apresentar baixa magnitude, e a seleção fenotípica não pode ser realizada em nível de plantas, mas baseada em médias de experimentos com repetições, conduzidas em diversos ambientes para minimizar os efeitos destes e suas interações com os genótipos. A linhagem L08-05F apresentou maior nível de stay green que a linhagem L38-05D e, portanto, pode ser utilizada como fonte de alelos favoráveis para serem transferidos para outras linhagens visando aumentar o nível deste caráter em linhagens que apresentarem baixos níveis de senescência retardada. / Several researches have reported that the increase in maize productivity could be attributed to the tolerance to abiotic stresses rather than to an increase on a plant productivity per se. Moisture stress is one of the most important stresses that reduce the maize productivity, but because of the difficulties for the direct selection for tolerance to moisture stress secondary traits as delayed senescence, also known as stay green trait, has been employed for this purpose. However, there is limited information reported on the inheritance of this trait. Thus, the objective of this research was to study the inheritance of the stay green trait in maize using the design III (Comstock and Robinson, 1952). One hundred F2:3 progenies were developed from a population derived from the cross between the inbred lines L08-05F and L38-05D; and these progenies were backcrossed to the inbred parents giving rise to 200 backcrossed progenies. These progenies were evaluated in ten environments, with two replications per environment, in Piracicaba City, São Paulo State, using the experimental design ?-lattice. The stay green trait was recorded in ten competitive plants per plot 120 days after sowing, using a scale with scores from 1 to 5, where score 1 was assigned to the plants with all leaves above the ear and at least two leaves below the ear green, and score 5 was assigned to plants with all leaves senescent. The trait days to silking was also recorded and used as covariate to adjust the maturation variation of the backcrossed progenies, and the mean of the plots was used for analysis. The estimate of the additive variance was quite larger than the dominance variance, the additive x environment variance was quite larger than the additive variance, and the average level of dominance was partial dominance, but since the population was in linkage disequilibrium the level of dominance may be overestimated. The heritability coefficient on a plant level was of low magnitude (~25%) while that one on a mean level presented high magnitude (~70%). These results indicated that the additive effects were more important than the dominance effects for the control of the stay green trait, and that the additive effects are not consistent across the environments. Therefore, the level of heterosis should present low magnitude, and the phenotypic selection should not be conducted on a plant level; instead selection should be based on the means of replicated experiments assessed in several environments to minimize their effects and the genotype by environment interactions. The inbred line L08-05F presented higher level of stay green than the inbred L38-05D and thus the former inbred could be used as a source of favorable alleles to be transferred to others inbreds to increase the level of this trait in inbreds that have low levels of delayed senescence.

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2017-03-06T16:25:25Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação_Mauricio_Ferrari.pdf: 1308879 bytes, checksum: 47b7ba5b511198a17226bd8456ede375 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-03-09T20:22:03Z (GMT) No. of bitstreams: 2 Dissertação_Mauricio_Ferrari.pdf: 1308879 bytes, checksum: 47b7ba5b511198a17226bd8456ede375 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-03-09T20:22:03Z (GMT). No. of bitstreams: 2 Dissertação_Mauricio_Ferrari.pdf: 1308879 bytes, checksum: 47b7ba5b511198a17226bd8456ede375 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-02-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / No melhoramento genético de milho, a seleção precoce de progênies é uma etapa minuciosa e demanda critérios rigorosos do melhorista. Neste sentido, a utilização de técnicas biométricas auxilia na avaliação das constituições genéticas. Dessa forma, o objetivo deste trabalho é estimar e identificar associações fenotípicas, genéticas e de ambiente em progênies S1, assim como estimar a herdabilidade e quantificar a variância genética por meio de análises multivariadas em progênies S1 provenientes de populações crioulas de milho cultivadas na região Sul do Rio Grande do Sul. O experimento foi conduzido na área experimental do Centro de Genômica e Fitomelhoramento, da Universidade Federal de Pelotas, localizada no Centro Agropecuário da Palma, no munícipio de Capão do Leão – RS, sob as coordenadas geográficas: latitude 31°45’ S, longitude 52°29’ O, com altitude média de 13 metros. O delineamento experimental utilizado foi de blocos aumentados, com dez grupos de progênies S1, e duas testemunhas comerciais, os híbridos simples Pioneer 30F53 e Agroeste 1590, alocados em quatro repetições. As progênies S1 foram obtidas após a autofecundação de plantas aleatórias nas populações crioulas de milho. Sendo estas: Amarelão, Argentino Branco, Argentino Amarelo, Branco Roxo Índio, Branco Oito Carreiras, Caiano Rajado, Cateto Branco, Criolão e Dente de Ouro, e da variedade de polinização aberta (VPA) BRS Planalto. Em cada progênie S1 foram avaliadas 40 plantas. Os caracteres avaliados foram: Altura de Inserção da espiga (AE): Altura de Planta (AP); Diâmetro do colmo (DC): Comprimento da haste principal do pendão (CHP): Número de ramificações primárias do pendão (NRP): Número de dias para o florescimento (NDF): Comprimento da espiga (CE): Diâmetro da Espiga (DE): Massa da espiga (ME): Profundidade dos grãos (PFG). Realizou-se a análise de correlação fenotípica, genotípica e de ambiente, de parâmetros genéticos e distância genética. O comprimento da espiga possui correlação fenotípica e genética forte e positiva com a massa da espiga, e pode ser utilizado para seleção indireta de progênies S1 com maior massa de espiga, independentemente da origem de formação das progênies. Para as demais associações, as progênies S1 apresentam correlações genéticas e fenotípicas específicas tanto em sentido como em magnitude, dificultando a definição de estratégias abrangentes de seleção indireta baseada na correlação entre caracteres. As progênies S1 Caiano Rajado, Criolão, Branco Roxo Índio, BRS Planalto, Dente de Ouro, Amarelão e Branco Oito Carreiras possuem padrões de herdabilidade semelhantes para os caracteres estudados. Os caracteres profundidade de grão e altura de inserção da espiga expressam as maiores estimativas de herdabilidade no sentido amplo. As progênies S1 provenientes de populações crioulas de milho apresentam variabilidade genética para os caracteres de importância agronômicos estudados. / In maize genetic breeding, early progeny selection is a meticulous step, and it demands rigorous criteria from the breeder. In this sense, the use of biometric techniques assists on evaluating genetic constitutions. Therefore, the aim of this work is to estimate and identify phenotypic, genetic and environmental associations in S1 progenies, as well as to estimate heritability and to quantify the genetic variance through multivariate analyzes of S1 progenies from landrace maize populations grown in southern Rio Grande do Sul. The experiment was conducted at the experimental area of the Center of Genomics and plant breeding of the Federal University of Pelotas, located in the Palma Agricultural Center, city of Capão do Leão-RS, with geographic coordinates: 31°45’ S latitude, 52°29’ O longitude, and average altitude of 13 meters. The experimental design used was augmented blocks with ten S1 progeny groups and two commercial controls, the single cross hybrids Pioneer 30F53 and Agroeste 1590, allocated in four repetitions. The S1 progenies were obtained after self-fertilization of random plants in the landrace maize populations. Being these: Amarelão, Argentino Branco, Argentino Amarelo, Branco Roxo Índio, Branco Oito Carreiras, Caiano Rajado, Cateto Branco, Criolão and Dente de Ouro, and the open pollinated variety (OPV) BRS Planalto. 40 plants were evaluated in each S1 progeny. The evaluated characters were: Spike Insertion Height (SH); Plant Height (PH); Stem Diameter (SD), Main Tassel Stem Length (TSL); Number of Primary Ramifications of the Tassel (NPR); Number of Days for Flowering (NDF); Spike Length (SL); Spike Diameter (SD); Spike Mass (SM); Grains Depth (GD). The analysis of phenotypic, genotypic and environmental correlation of genetic parameters and genetic distance was performed. Spike length presented a strong and positive genetic and phenotypic correlation with spike mass, and may be used for indirect selection of greater spike mass S1 progenies, regardless the progeny origin. For the other associations, S1 progenies present specific genetic and phenotypic correlations in both sense and magnitude, making it difficult to define indirect selection strategies based on correlation between characters. The S1 progenies Caiano Rajado, Criolão, Branco Roxo Índio, BRS Planalto, Dente de Ouro, Amarelão and Branco Oito Carreiras present similar heritability patterns for the characters in study. The characters grain depth and spike insertion height express the largest estimates of heritability in the broad sense. The S1 progenies from landrace maize populations present genetic variability for the agronomic traits studied.

The latter part of the reproductive growth phase in chickpea (<i>Cicer arietinum</i> L.) often coincides with declining temperature and wet conditions in western Canada, in sharp contrast to many other growing environments. This exacerbates the indeterminate nature of the crop, leading to excessive canopy development, and subsequently resulting in delayed maturity. The objectives of this study were to: i) determine the genetic relationships of short internode, double podding and early flowering traits with earliness of crop maturity; ii) determine the genetic control of major earliness traits in chickpea; iii) assess the patterns of post-flowering dry matter accumulation and partitioning to reproductive parts as related to earliness. <p>The results showed that double podding significantly reduced the number of days taken to maturity, under the conditions where this trait was sufficiently expressed. The best double podding genotypes, i.e. those with 1535% of the podded nodes bearing double pods, were about one week earlier than their single podding counterparts and standard checks. A physiological study revealed that the double podding parental genotype 272-2 partitioned a relatively greater proportion (about 58%) of the total dry matter to pods compared to 4254% in the single podding genotypes. Double podding increased the total number of pods set, and thus the increased demand for assimilates may have precluded further production of stems and leaves, resulting in an earlier transition of reproductive growth to physiological maturity. Days to flowering was positively associated with days to maturity, and partial path analysis revealed that days to flowering contributed to days to maturity indirectly via days to first pod maturity. Days to flowering explained 32% of the variation in days to first pod maturity. However, the short internode trait had an undesirable effect, in that all the short internode segregants were too late to mature. <p>Genetic studies revealed that days to flowering was determined by two major genes plus polygenes in chickpea in the short-season temperate environment of western Canada. The two major genes control over 65% of the phenotypic variation. Also, the additive component of genetic variance was significant for days to first podding, days to first pod maturity, reproductive period, and days to maturity; which is desirable for development of superior inbred cultivars of chickpea. These key phenological traits are interrelated but could be manipulated separately in the breeding process. Additional gain in earliness of crop maturity may be achieved through combined selection for these traits.

The latter part of the reproductive growth phase in chickpea (<i>Cicer arietinum</i> L.) often coincides with declining temperature and wet conditions in western Canada, in sharp contrast to many other growing environments. This exacerbates the indeterminate nature of the crop, leading to excessive canopy development, and subsequently resulting in delayed maturity. The objectives of this study were to: i) determine the genetic relationships of short internode, double podding and early flowering traits with earliness of crop maturity; ii) determine the genetic control of major earliness traits in chickpea; iii) assess the patterns of post-flowering dry matter accumulation and partitioning to reproductive parts as related to earliness. <p>The results showed that double podding significantly reduced the number of days taken to maturity, under the conditions where this trait was sufficiently expressed. The best double podding genotypes, i.e. those with 1535% of the podded nodes bearing double pods, were about one week earlier than their single podding counterparts and standard checks. A physiological study revealed that the double podding parental genotype 272-2 partitioned a relatively greater proportion (about 58%) of the total dry matter to pods compared to 4254% in the single podding genotypes. Double podding increased the total number of pods set, and thus the increased demand for assimilates may have precluded further production of stems and leaves, resulting in an earlier transition of reproductive growth to physiological maturity. Days to flowering was positively associated with days to maturity, and partial path analysis revealed that days to flowering contributed to days to maturity indirectly via days to first pod maturity. Days to flowering explained 32% of the variation in days to first pod maturity. However, the short internode trait had an undesirable effect, in that all the short internode segregants were too late to mature. <p>Genetic studies revealed that days to flowering was determined by two major genes plus polygenes in chickpea in the short-season temperate environment of western Canada. The two major genes control over 65% of the phenotypic variation. Also, the additive component of genetic variance was significant for days to first podding, days to first pod maturity, reproductive period, and days to maturity; which is desirable for development of superior inbred cultivars of chickpea. These key phenological traits are interrelated but could be manipulated separately in the breeding process. Additional gain in earliness of crop maturity may be achieved through combined selection for these traits.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Common bean cultivars development with high nutritional quality joined with grain yield is desirable. In consequence, of this study evaluated the genitors, F1 and its reciprocals, F2 and backcrosses populations obtained in the combination among four genitors. For protein content were used TPS Nobre, Guapo Brilhante, BRS Expedito and UTF-1 Balisa. For fibers content, CNFP 8100, FT 96-1282, Valente and Varre Sai were used. The crossings were performed inside a greenhouse using complete diallel approach and assessed in the field using a randomized complete block design with two replications. The laboratory analyses were realized to protein and dietary fiber content. Negative phenotypic correlation between protein content and grain yield was observed. The crossings between the high protein content genitors produced F2 populations with high protein content. Genetic variability was observed for genitors, F1 s and their reciprocals for dietary fiber content. The largest heritability estimates were obtained for fibers content and the smallest for grain yield. Phenotypic correlation between dietary fiber, their different fractions (soluble and insoluble) and grain yield was not observed. Phenotypic correlation between fiber insoluble and dietary fiber content was positive, wile between soluble and insoluble fiber was negative. In the populations studied, the selection for protein content and fibers associated with high grain yield could be performed with success as long as we have better understanding of the genetic control, environmental effect and genotype x environment interaction that influence these characteristics. / O desenvolvimento de cultivares de feijão com alta qualidade nutricional aliado ao alto rendimento de grãos é desejável. Como conseqüência, este trabalho buscou avaliar os genitores e as populações F1 , recíprocos, F2 e retrocruzamentos obtidos das combinações entre quatro genitores para o teor de proteína (TPS Nobre, Guapo Brilhante, BRS Expedito e UTF-1 Balisa) e de quatro genitores para o teor de fibras (CNFP 8100, FT 96-1282, Valente e Varre Sai). Os cruzamentos foram realizados em casa-de-vegetação, segundo a metodologia de dialelos completos, e avaliados a campo utilizando o delineamento experimental de blocos ao acaso com duas repetições. As análises laboratoriais foram realizadas quanto aos teores de proteína bruta e fibra alimentar. Correlação fenotípica negativa entre proteína bruta e rendimento de grãos foi observada. Hibridações controladas entre genitores com alto teor de proteína, possibilitaram a obtenção de populações F2 com alto teor protéico. Foi encontrada variabilidade genética para teor de fibra alimentar para genitores, F1 s e recíprocos. As maiores estimativas de herdabilidade foram observadas para teor de fibras e as menores para rendimento de grãos. Não foi encontrada correlação fenotípica entre fibra alimentar, suas diferentes frações (solúvel e insolúvel) e rendimento de grãos. As correlações fenotípicas entre o teor de fibra insolúvel e de fibra alimentar foram positivas, enquanto que entre fibra solúvel e insolúvel foram negativas. Nas populações estudadas, a seleção para teor de proteína e de fibras associadas ao elevado rendimento de grãos poderá ser realizada com sucesso, desde que se tenha melhor entendimento do controle genético, dos efeitos ambientais e da interação genótipo x ambiente que atuam nessas características.

In most breeding programmes breeders use phenotypic data obtained in breeding trials to rank the performance of the parents or progeny on pre-selected performance criteria. Through this ranking the best candidates are identified and selected for breeding or production purposes. Best Linear Unbiased Prediction (BLUP), is an efficient selection method to use, combining information into a single index. Unbalanced or messy data is frequently found in tree breeding trial data. Trial individuals are related and a degree of correlation is expected between individuals over sites, which can lead to collinearity in the data which may lead to instability in certain selection models. A high degree of collinearity may cause problems and adversely affect the prediction of the breeding values in a BLUP selection index. Simulation studies have highlighted that instability is a concern and needs to be investigated in experimental data. The occurrence of instability, relating to collinearity, in BLUP of tree breeding data and possible methods to deal with it were investigated in this study. Case study data from 39 forestry breeding trials (three generations) of Eucalyptus grandis and 20 trials of Pinus patula (two generations) were used. A series of BLUP predictions (rankings) using three selection traits and 10 economic weighting sets were made. Backward and forward prediction models with three different matrix inversion techniques (singular value decomposition, Gaussian elimination - partial and full pivoting) and an adapted ridge regression technique were used in calculating BLUP indices. A Delphi and Clipper version of the same BLUP programme which run with different computational numerical precision were used and compared. Predicted breeding values (forward prediction) were determined in the F1 and F2 E. grandis trials and F1 P. patula trials and realised breeding performance (backward prediction) was determined in the F2 and F3 E. grandis trials and F2 P. patula trials. The accuracy (correlation between the predicted breeding values and realised breeding performance) was estimated in order to assess the efficiency of the predictions and evaluate the different matrix inversion methods. The magnitude of the accuracy (correlations) was found to mostly be of acceptable magnitude when compared to the heritability of the compound weighted trait in the F1F2 E. grandis scenarios. Realised genetic gains were also calculated for each method used. Instability was observed in both E. grandis and P. patula breeding data in the study, and this may cause a significant loss in realised genetic gains. Instability can be identified by examining the matrix calculated from the product of the phenotypic covariance matrix with its inverse, for deviations from the expected identity pattern. Results of this study indicate that it may not always be optimal to use a higher numerical precision programme when there is collinearity in the data and instability in the matrix calculations. In some cases, where there is a large amount of collinearity, the use of a higher precision programme for BLUP calculations can significantly increase or decrease the accuracy of the rankings. The different matrix inversion techniques particularly SVD and adapted ridge regression did not perform much better than the full pivoting technique. The study found that it is beneficial to use the full pivoting Gaussian elimination matrix inversion technique in preference to the partial pivoting Gaussian elimination matrix inversion technique for both high and lower numerical precision programmes. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Genetics / unrestricted