Minimum Number of Measurements for Accurate Evaluation of Qualitative Traits in Urochloa brizantha

Research Article
Minimum Number of Measurements for Accurate Evaluation of Qualitative Traits in Urochloa brizantha

Francisco Eduardo Torres, Cacilda Borges do Valle, Beatriz Lempp, Paulo Eduardo Teodoro, Adriano dos Santos and Carlos Antonio da Silva Junior

Journal of Agronomy, 2015, 14(3), 180-184.


This work aimed to identify the most effective method to estimate the coefficient of repeatability in genotypes of U. brizantha and predict the minimum number of measurements required for some qualitative traits. It were evaluated 9 genotypes in a randomized block design with two replications in the rainy season and drought in 2000. It were evaluated the following qualitative traits: volume of gas, in mL, packed in fast and slow fraction, crude protein; neutral detergent fiber, acid detergent fiber, cellulose, lignin sulfuric acid, silica and in vitro digestibility of organic matter. The repeatability coefficient (r) was estimated considering different strategies: Analysis of variance, principal component analysis based on the correlation matrix (CPCOR), principal components analysis based on the matrix of phenotypic variance and covariance and structural analysis based on the correlation matrix. The CPCOR method, provided more accurate estimates of r and the number of measurements required for the qualitative traits assessed due to the cyclical behavior of genotypes of U. brizantha. The traits neutral detergent fiber, cellulose and silica require two measurements, while the remaining characters require four measurements to predict the actual value of genotypes of U. brizantha with a minimum accuracy of 80%, by CPCOR method.

ASCI-ID: 31-622

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