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Repeatability and genotypic stability of agronomic characteristics in Panicum maximum Jacq.

Mariane Rodrigues Ferreira1*, Janaina Azevedo Martuscello2, Thiago Gomes dos Santos Braz3, Artur Amaral Nascimento4, Liana Jank5, Juliana Aparecida de Assis6, Otávio Goulart de Almeida6, Gabriel de Assis Reis6, Márcia Vitória Santos7, and Mateus Figueiredo Santos5

In experiments with selection of perennial plants, the initial performance is expected to be maintained throughout the productive life. The probability of repeating the agronomic response can be evaluated by the repeatability coefficient. The objective was to estimate repeatability coefficients of agronomic characteristics in Panicum maximum Jacq. using different methods and identify the best combinations between harvests according to the genotypic stabilization. Seventeen genotypes were evaluated in a randomized complete block design with three replicates. The coefficients of repeatability were estimated by the methods: ANOVA, structural analysis based on the mean of the correlation coefficients (SACOR), analysis of principal components based on the covariance matrix (PCCOV) and correlation matrix (PCCOR). In the genotypic stabilization, coefficients estimated by ANOVA and PCCOR were used. For total DM, repeatability coefficients ranged from 0.3500 to 0.4300 by the ANOVA and PCCOR methods, respectively. High repeatability coefficients were found for the characteristic leaf DM, while low coefficients were observed for leaf and stem percentages and leaf:stem ratio. For the genotypic stabilization of total DM and leaf:stem ratio, the best coefficients were observed for the combination of harvests 5 to 8. There are variations in the estimate of repeatability by different methods and the highest coefficients were those of the principal components based on the correlation and covariance matrices. For the genotypic stabilization, the best coefficients of repeatability and determination were observed for the harvests performed in the second rainy period.

Key words: Forage, leaf:stem ratio, repeated measures.

1Universidade Estadual Paulista, Via de Acesso Prof. Paulo Donato Castelane, Castellane s/n, Vila Industrial, Jaboticabal, São Paulo, Brasil.*Corresponding author (mariane_candeias@hotmail.com).
2Universidade Federal de São João del-Rei, Avenida Visconde do Rio Preto, s/n, Colônia do Bengo, São João del-Rei, Minas Gerais, Brasil.
3Universidade Federal de Minas Gerais, Avenida Universitária 1000, Bairro Universitário, Montes Claros, Minas Gerais, Brasil.
4Universidade Estadual do Sudoeste da Bahia, Praça Primavera, 40, Bairro Primavera, Itapetinga, Bahia, Brasil.
5Embrapa Gado de Corte, Empresa Brasileira de Pesquisa Agropecuária, Campo Gran

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