Repeatability of morpho-agronomic characters of Theobroma grandiflorum fruits

Repetibilidade de caracteres morfoagronômicos de frutos de Cupuaçuzeiros

Ayulle Thalía Watson Alcoforado Cássia Ângela Pedrozo Marcos Miguel Mayer Hyanameyka Evangelista de Lima-Primo About the authors

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.

Index terms
genetic variability; selection of genotypes; phenotypic correlation

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