Tamanho de parcela e efeito de bordadura no melhoramento de Urochloa ruziziensis

Abstract

Resumo -O objetivo deste trabalho foi avaliar a necessidade de bordadura e estimar o tamanho ótimo de parcela em experimentos para avaliação de Urochloa ruziziensis. Foram avaliadas a altura das plantas e a produção de massa verde de oito progênies de meio-irmãos de U. ruziziensis, em dois cortes. Utilizou-se o delineamento de blocos ao acaso, com quatro repetições e parcelas de 16 m 2 . Cada parcela foi subdividida em 32 estratos de 0,5 m 2 , sendo cada estrato considerado como uma unidade básica. Para determinar a necessidade de bordadura, foi realizada análise de variância, tendo-se considerado a posição da unidade básica na parcela. As estimativas do tamanho ótimo da parcela foram realizadas pelo método da máxima curvatura do coeficiente de variação e pelo método da reamostragem. O uso de bordaduras não altera o desempenho médio e a classificação das progênies de meio-irmãos avaliadas. O emprego de parcelas com 3 m 2 é suficiente para obter boa precisão experimental em experimento com progênies de meio-irmãos de U. ruziziensis.Termos para indexação: Brachiaria ruziziensis, melhoramento genético, planejamento experimental, precisão experimental. Plot size and border effect on breeding of Urochloa ruziziensisAbstract -The objective of this work was to assess the need for a border area and to estimate the optimum plot size in experiments for the evaluation of Urochloa ruziziensis. Plant height and green mass production of eight half-sib progenies of U. ruziziensis were evaluated in two cuttings. A randomized complete block design was used, with four replicates and 16 m 2 plots. Each plot was subdivided into 32 strata of 0.5 m 2 , with each stratum being considered as a basic unit. To determine the need for a border area, analysis of variance was carried out considering the position of the basic unit in the plot. Estimates of optimum plot size were made by the maximum curvature of the coefficient of variation method and by the resampling method. The use of borders does not affect the mean performance and classification of the half-sib progenies evaluated. The use of 3 m 2 plots is enough to obtain good experimental accuracy in an experiment with half-sib progenies of U. ruziziensis.

Plot size for evaluation of Arabica coffee yield

“…At Site 1, the accuracy did not represent the experimental precision because it was not detecting differences between treatments. The same situation occurred in the study by Dias et al (2013) of estimation of plot size for Urochloa ruziziensis.…”

“…The estimates of plot size were obtained by the resampling method (Dias et al, 2013), the maximum curvature of the coefficient of variation method (MCCVM) and the linear-plateau segmented model method (LPSMM) (Paranaíba et al, 2009a).…”

“…The variance computed to estimate the plot size is the variance between the basic units within plots (Dias et al, 2013) because in this case, the information obtained between the basic units is the variance within plots.…”

Contribution of Additive and Dominance Effects on Agronomical and Nutritional Traits, and Multivariate Selection on Urochloa spp. Hybrids

“…[3], according to the limits set by Resende and Duarte (2007). The ideal plot size for progenies of U. ruziziensis was ?3 m 2 (Dias et al, 2014), or a line of 3 m with six plants (Souza Sobrinho et al, 2010, 2011. In this experiment, plots with five plants and 2.25 m 2 plant −1 were used, which is more than commonly reported for evaluation of progenies.…”

Urochloa spp. multivariate performance: Similarities and divergences among intra‐ and interspecific populations

“…On the other hand, the increment of plot size in P1 (five plants compared with one plant in P0) allowed for better evaluation of the genetic variability among genotypes for the agronomical and nutritional traits, which increased the heritability in P1. This was expected for agronomic traits due to the influence of plot size increment on experimental precision on forage breeding (Dias et al, 2014). Seed quality is evaluated in parallel to the agronomic traits, which are normally the main traits used to select individuals during the early phases.…”