Abstract
Abstract The objective of this study was to estimate coefficients of repeatability, to determine the minimum number of fruits necessary for genotype selection and to estimate phenotypic correlation coefficients between morpho-agronomic characters of Theobroma grandiflorum fruits. It was evaluated twenty - two genotypes of an agroforestry system implanted in the municipality of Cantá - RR. Ten fruits per genotype were collected and evaluated for longitudinal length, transverse diameter, total weight, peel thickness, peel weight, pulp weight, placental weight and wet seed weight. Four statistical methods were used to estimate the repeatability coefficients: variance analysis, main components based on the correlation matrix and the covariance matrix, and structural analysis based on the correlation matrix. The number of measurements needed to predict the real value of the genotypes and the Pearson correlation coefficients among the characters were also estimated. The repeatability coefficients ranged from low to moderate, with 10 fruits per plant generally required, with 85% of confidence, in order to make an effective selection for most of the characters studied. There are possibilities of indirect gains for fruits with greater amount of pulp through the selection of larger and / or heavier fruits.
Highlights
The cupuassu [Theobroma grandiflorum (Willd. ex Spreng.) K
The objective of this study was to estimate repeatability coefficients, to determine the minimum number of fruits required for genotype selection and to estimate phenotypic correlation coefficients among morpho-agronomic characters of cupuassu fruits
The fruits presented phenotypic variation for the evaluated characters, with a diameter varying from 8 cm to cm, length from cm to 31 cm, fruit weight from 300 g to 1940 g and pulp weight from 80 g to 610 g
Summary
The cupuassu [Theobroma grandiflorum (Willd. ex Spreng.) K. In addition to the characters such as quality and resistance to the main pests and diseases, the selection of genotypes that present fruits of larger size and with a higher percentage of pulp is desirable for the improvement of the species. In breeding programs of perennial species, which require long periods of time for evaluation and selection of genotypes, methods capable of increasing the process efficiency should be prioritized. Among these methods is mentioned the repeatability coefficient, which can be estimated when the measurement of a given character is repeated, in time or space, in the same individual. The parameter measures the proportion of the total variance that is explained by the genetic effects and by the effects of the permanent environment, attributed to the common environment (CRUZ et al, 2004)
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