Doutorado em Agronomia (EA)
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Navegando Doutorado em Agronomia (EA) por Por Orientador "CHAVES, Lázaro José"
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Item Variabilidade de plantas e progênies de populações naturais de Hancornia speciosa Gomes do Cerrado(Universidade Federal de Goiás, 2008-07-30) GANGA, Rita Maria Devós; NAVES, Ronaldo Veloso; http://lattes.cnpq.br/2740049203016314; CHAVES, Lázaro José; http://lattes.cnpq.br/9990967290797379The mangaba tree (Hancornia speciosa Gomes) is a fruit tree native from Brazil with potential for domestication, due to its excellent smell, flavor and texture. However, genetic conservation and breeding programs of these species are in an initial developmental phase. This way, this research aimed to characterize trees and fruits of natural populations of H. speciosa, as well as evaluate the distribution of phenotypic variability among them; evaluate progenies of mangaba trees that compose the Escola de Agronomia e Engenharia de Alimentos of Universidade Federal de Goiás (EA/UFG) germplasm collection and estimate genetic parameters for the initial development of plants in the field. Mangaba trees populations have been sampled in different locations of the Brazilian Cerrado, including the states of Goiás, Tocantins, Mato Grosso, Mato Grosso do Sul, and Bahia, totaling 109 mother plants of 35 populations of the botanic varieties pubescens, gardneri, speciosa and cuyabensis. In relation to the trees, plant height, stem perimeter, and number of fruits per plant were taken. From a sample of five fruits per plant, individual measures have been taken, such as: length, diameter, weight, total weight of seeds, average seed weight, pulp plus peel weight, seed number per fruit, pulp plus peel yield, fruit shape and color and estimated production. Seeds from these mother plants were used to install the EA/UFG mangaba germplasm collection in December 2005, in a randomized complete block design with 57 treatments, four replications and one plant per plot in a 5 m x 6 m spacing. The treatments were open pollination progenies, originated from 28 natural populations. The characteristics plant height and stem basal diameter were evaluated in all plants from January 2006 to August 2007, which resulted in 20 data readings. Data from each plant has been transformed into growth rate. The analyses of variance and the genetic parameter estimates were obtained to the growth rate and to the data of latest reading of stem diameter and plant height. The progress was estimated by simulating genetic selection in both sexes and maternal selection. In Cerrado conditions, the results showed that H. speciosa mother plants show high levels of phenotypic variation in fruit characters and most of this variation is among populations. There is a large phenotypic variability in the varieties too. H. speciosa var. gardneri and H. speciosa var. pubescens fruits are larger and heavier. The botanic variety gardneri shows gait more high than the others varieties. In the varieties gardneri and pubescens predominate round shape and light green color, while in speciosa and cuyabensis predominate oblong shape and dark yellow and dark green colors, respectively. The varieties gardneri and pubescens stand out as the most promising for selection based on fruit size and fruit weight. The mangaba tree progenies of the germplasm collection of EA/UFG present high levels of genetic variation in stem diameter and plant height and to their growth rates. Most of the genetic variation in stem diameter is within populations and to plant height is among populations. H. speciosa var. cuyabensis and H. speciosa var. gardneri show greater growth in stem diameter and plant height. On account of the expected progress of selection, the collection can be used as seed orchard or clonal garden, without plant thinning, collecting seeds or buds of superior plants. The maternal selection is recommended to maintain greater variability in future breeding cycles, permitting progress from selection and maintaining the germoplasm collection intact.Item ESTRUTURA GENÉTICA POPULACIONAL E FLUXO GÊNICO EM Dipteryx alata VOGEL (FABACEAE) NO CERRADO(Universidade Federal de Goiás, 2009-01-22) SOARES, Thannya Nascimento; TELLES, Mariana Pires de Campos; http://lattes.cnpq.br/4648436798023532; CHAVES, Lázaro José; http://lattes.cnpq.br/9990967290797379The goal of this study was to evaluate the genetic structure and the spatial pattern of intra and interpopulational gene flow of Dipteryx alata Vogel, based on nuclear and chloroplastidial microsatellite markers. Primers were developed based on sequencing of random fragments from a shotgun genomic library for detection of microsatellite regions. 12 microsatellites regions were obtained from 688 sequences, which allowed the construction of pairs of primers. These regions are composed of motifs with two to six nucleotides, ranging from 136 to 380 base pairs. This shows that the random sequencing strategy from shotgun libraries is interesting because it allows the achievement of primers for repetitive regions with different motifs. Two of these loci (Da_E06 e Da_E12) were polymorphic with three alleles each. He estimation for these loci showed satisfactory values (0.2946 and 0.2879, respectively), considering the number of alleles. Also, we used a transferred primer from the species Phaseolus vulgaris (BM164) for D. alata. Moreover, other two chloroplastidials microsatellite primers were used for molecular analyses of georeferenced subpopulations, totalizing 775 plants distributed over the natural occurrence area of Cerrado. 210 of these plants were collected and georeferenced one by one along the margins of the Araguaia River in the states of Mato-Grosso (RAMT) and Goiás (RAGO) for spatial distribution of genetic variability in local scale analysis. The relationship between estimations of genetic diversity parameters with patterns of potential distribution of species was evaluated. This was used to test the hypothesis that the genetic variability of D. alata populations is distributed according to the central-periphery model. D. alata subpopulations showed considerable high levels of genetic variability that was significantly structured among subpopulations and well structured in space, both for nuclear and chloroplastidial data. The estimation of the apparent cross-fertilization rate (ta = 1.0575) indicates that the species is allogamous. Estimations of migration rates by pollen and by seeds were lower than one, indicating that seed dispersal contributes more effectively for total gene flow. Estimates of the genetic diversity parameters from the Araguaia River population showed similar values between both margins. The estimation of the apparent cross-fertilization rate (0.9434) indicated that the Araguaia River is not a physical barrier to effective gene flow. The effective size of the neighborhood, i.e., the mean number of individuals in an area where panmixia occurs was 85.64 and 22.99 for nuclear and chloroplastidial data, respectively, indicating that seed dispersal is more restricted. The correlogram generated with chloroplastidial data presented a cline pattern of variance more evident than with nuclear data, suggesting that the presence of spatial genetic structure is being more influenced by seed dispersal. We observed that the genetic parameters do not follow a classical central-periphery model, because peripheral population (according to geographical distribution of sampling locations) tended to demonstrate higher values for these estimations, mainly the South and Western subpopulations. The relationship found between the fixation index (f) with human impact indicated that the subpopulations evaluated can be affected by fragmentation process and land use, probably caused by the recent human colonization in Cerrado biome.