Updating the ranking of the coefficients of variation from maize experiments

Abstract

ABSTRACT. The objective of this study was to update the ranking of the coefficients of variation (CVs) from maize experiments and evaluate the accuracy of the data from the latest Brazilian publications. We rank-ordered the CVs for grain yield, plant and ear heights, number of ears per plant, and weight of commercial ears, except for the weight of 100 grains. The data were obtained from 143 scientific papers published from 2005 to 2010. The classification was based on the average (m) and standard deviation (SD) and the CVs were ranked as low, intermediate, high and very high. All of the random variables had the CVs normally distributed. For most of the traits, we observed a large difference between the ranks from Scapim and Pimentel Gomes. In summary, the coefficients of variation have to be classified for each variable, significant improvement occurred in the accuracy of the national maize experiments in the last 15 years, and they still require periodic updating.Keywords: experimental precision, experimental design.Atualização da proposta de classificação dos coeficientes de variação para a cultura do milho RESUMO. O objetivo desse trabalho foi fazer a atualização na proposta de classificação dos coeficientes de variação (CV) para a cultura do milho e avaliar a qualidade dos dados dos artigos mais recentes publicados no Brasil. Os CV das diferentes variáveis aleatórias foram obtidos a partir da consulta de 143 artigos científicos publicados de 2005 e 2010. As faixas de classificação dos (CV) foram baseadas na média (m) e no desvio-padrão (DP) da seguinte forma: baixo; médio; alto; muito alto. Todos os cv das variáveis aleatórias apresentaram distribuição normal. Foi possível observar que para a maioria dos caracteres avaliados houve uma grande diferença entre a classificação proposta e a de Pimentel-Gomes. Houve melhoria significativa na qualidade experimental na cultura do milho para os principais caracteres produtividade de grãos, alturas de planta e espiga, número de espigas por planta e peso de espigas comerciais, sendo a única exceção o peso de 100 grãos. Conclui-se que as faixas de classificação de coeficientes de variação têm que ser específica para cada variável, é necessária atualização periódica da classificação dos coeficientes de variação e nos últimos 15 anos, no Brasil, a qualidade da experimentação com cultura do milho teve uma melhora significativa.Palavras-chave: precisão experimental, delineamento experimental.

An accurate prediction of maize crosses using diallel analysis and best linear unbiased predictor (BLUP)

“…This is of paramount importance for obtaining genetic gains in terms of hybrid crosses among populations since the success of the breeding program depends on variability to optimize the selection process (Machado, 2014). For all analyzed variables, the variation coefficients were at or below the ideal described by Hallauer et al (2010) and Fritsche-Neto et al (2012) and revealed high experimental precision.…”

Combining abilities and inbreeding depression in commercial maize hybrids

“…The experimental coefficients of variation (CVs) obtained in the first experiment (2011/2012 harvest) were 11.23%, 3.71% and 5.59% for yield, plant height and ear height, respectively. In the second experiment (2012/2013 harvest), the respective CVs reached 14.17%, 4.46% and 7.34%, indicating satisfactory experimental precision (SCAPIM et al, 1995;FRITSCHE-NETO et al, 2012). The adoption of lattice was also verified as a satisfactory experimental design because all of the estimators of the design efficiency were greater than 100%.…”

Mixed models and multivariate analysis for selection of superior maize genotypes

“…Therefore, the genotypes presented high productivity estimates, since average productivity in Brazil is about 4.2 t ha -1 (Lyra et al, 2014). The variation coefficients for all variables were within the normal range, revealing good experimental precision (Hallauer et al, 2010;Fritsche-Neto et al, 2012).…”