Variabilidade de plantas e progênies de populações naturais de Hancornia speciosa Gomes do Cerrado

• Autor(a) principal: GANGA, Rita Maria Devós
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tde/458
• topic: Conservação ex situ; Espécie nativa; Mangaba; Mangabeira; procedência; 1. Mangabeira - Conservação ex situ 2. Mangaba Cultivo - Cerrado 3.Espécie nativa 4. Plantas frutíferas Melhoramento genético; ex-situ conservation; native specie; mangaba; mangaba tree; origin; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::SILVICULTURA::GENETICA E MELHORAMENTO FLORESTAL

The 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.