The genus Paullinia includes the economically important P. cupana, known as guaraná in Brazil and more recently in the world market. Native Americans of the Maué and Andirá tribes cultivated P. cupana 'Sorbilis' in central Amazon, and the Barés cultivated the 'Typica' variety in the upper Negro River (Brazil). Cytological studies in the Sapindaceae family have concentrated on the diversity in number (from 2n = 14 to 96) and size of the chromosomes. In Paullinia, seven species have been karyotyped and all show 2n = 24. Meristem maceration, cellular dissociation and air-drying techniques were used for cytogenetic preparations and DNA content was determined by flow cytometry. Chromosome characterization and DNA content of Paullinia cupana Kunth 'Sorbilis' (Mart.) Ducke (Sapindaceae) were studied. The high chromosome number (2n = 210) fall into two cytomorphological groups: (a) a metacentric and submetacentric group showing 25 sets of three pairs of chromosomes (2-76); (b) a group containing only acrocentric showing 12 sets of two pairs of chromosomes (82-105), a homologous submetacentric pair (1) and an acrocentric pair (81). Mean nuclear DNA content of guaraná was 2C = 22.8 pg. A karyogram was set up showing a high chromosome number complement.
Resumo -O objetivo deste trabalho foi avaliar a repetibilidade da produção de sementes de 27 clones de guaraná (Paullinia cupana). Os clones foram avaliados em dez ensaios instalados em blocos ao acaso com duas repetições e três plantas por parcela, com espaçamento de 5x5 m. A produção de sementes foi avaliada por quatro anos (1998, 1999, 2000 e 2001) a partir do início da fase produtiva, após dois anos do plantio. O coefi ciente de repetibilidade foi estimado pelos métodos: análise de variância (ANOVA), componentes principais com base em matriz de correlações (CPCOR), componentes principais com base em matriz de variâncias e covariâncias fenotípicas (CPCOV) e análise estrutural com base na matriz de correlações (AECOR). Foram estimados também o número mínimo de observações e o coefi ciente de determinação. As estimativas dos coefi cientes de repetibilidade com base nos quatro anos, nos dez ambientes, foram relativamente baixas -0,2618 (AECOR), 0,3064 (CPCOR), 0,3183 (ANOVA) e 0,5308 (CPCOV) -e variaram de acordo com o método e o ambiente. São necessários, no mínimo, quatro anos de avaliação para a obtenção de valores genotípicos dos clones com coefi ciente de determinação de 80%.Termos para indexação: Paullinia cupana, análise de variância, análise estrutural, componente principal, seleção clonal. Seed yield repeatability of guarana clonesAbstract -The aim of this work was to evaluate the seed yield repeatability of 27 guarana clones. Ten assays were carried out for clone evaluation using a completely randomized block design, with two replicates and three plants per plot with a 5x5 m spacing. The seed yield was measured during four years (1998, 1999, 2000 and 2001) after the beginning of the production phase, two years after planting. Four methods were used for repeatability coeffi cient estimation: analysis of variance (ANOVA), principal components analysis based on correlation matrix (CPCOR), principal components analysis based on phenotypical variance and covariance matrix (CPCOV), and structural analysis based on correlation matrix (AECOR). Minimum observations number and determination coeffi cient were also evaluated. The repeatability coeffi cient estimates based on these four years, in all ten environments, were relatively low -0.2618 (AECOR), 0.3064 (CPCOR), 0.3183 (ANOVA) and 0.5308 (CPCOV) -and varied according to method and environment. At least four years of evaluation are necessary for obtaining the real genotypical value of the clones for an 80% determination coeffi cient.
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