Size and shape of plots for experiments with the sunflower

Abstract

2RESUMO -Na experimentação agrícola, a utilização do tamanho e da forma adequada de parcela são técnicas experimentais importantes para aumentar a precisão do experimento. Assim, objetivou-se nesse trabalho determinar o tamanho e forma adequada de parcela para experimentação em campo com girassol. Para isso, o experimento foi conduzido em blocos completos casualizados com 14 cultivares de girassol em 10 repetições. As parcelas foram constituídas de quatro fileiras de seis metros de comprimento, espaçadas de 0,7 m e 0,3 m entre plantas. A área útil da parcela (7,56 m 2 ), composta das duas fileiras centrais, foi dividida em 12 unidades básicas, cada uma constituída por três plantas na fileira (0,63 m 2 ), obtendo-se o rendimento de grãos de girassol. O tamanho conveniente da parcela experimental foi estimado pelo método de Hatheway e a sua forma adequada foi determinada pelo método da informação relativa. O método de Hatheway permitiu estimar diversos tamanhos convenientes de parcelas, muitos de tamanhos aplicáveis para experimentos de avaliação de cultivares de girassol. Parcela no formato retangular 1 x 6 (fileira com dezoito plantas e 3,78 m 2 de área útil), foi considerada a forma adequada para avaliação do rendimento de grãos de cultivares de girassol e, também, foi menor que o tamanho geralmente indicado nas pesquisas com a cultura do girassol. Palavras-chave: Helianthus annuus L.. Método de Hatheway. Método da informação relativa.ABSTRACT -In agricultural experimentation, the use of the appropriate size and shape for the plot is an important experimental technique for increasing the accuracy of the experiment. The aim of this work therefore was to determine a suitable plot size and shape for field experimentation on the sunflower. To do this, the experiment was carried out in a randomised design of complete blocks, with 14 sunflower cultivars in 10 replications. The plots consisted of four rows, each of six metres in length, at a spacing of 0.7 m, with 0.3 m between plants. The working area of the plot (7.56 m 2 ) comprising the two central rows, was divided into 12 basic units, each consisting of three plants per row (0.63 m 2 ), to obtain seed yield in the sunflower. A suitable plot size was estimated using Hatheway's method, with an appropriate shape being determined by the method of relative information. Hatheway's method made it possible to estimate several convenient plot sizes, many of them suitable for experiments to evaluate sunflower cultivars. A 1 x 6 rectangular plot (a row with 18 plants and a working area of 3.78 m 2 ) was considered the appropriate shape for evaluating grain yield in sunflower cultivars, and was also smaller than the size usually found in research into the sunflower crop.

Optimal plot size for experimental trials with Opuntia cactus pear

“…Thus, CVe is the factor with the greatest influence on the experimental plot dimension, followed by the index d, which determines the difference to be detected between treatments; the number of replicates and, finally, the number of treatments, with smaller effect on the plot size. Similar sequence on the order of importance of the factors was reported by Sousa et al (2016), Oliveira, Mello, Lima, Scolforo, andOliveira (2011), Muniz, Aquino, Simplicio, andSoares (2009) and Donato et al (2018) for sunflower, candeia, eucalyptus and banana crops, respectively.…”

“…Thomas (1974) interprets the index b>1 as the reflection of the negative correlation between the confronting plots, if each plot is composed of a single BEU. Sousa et al (2016) state that this argument is incomprehensible when the plot is formed by more than one BEU, since, normally, blank experimentation suggests competition between BEUs or high susceptibility of plants to environmental variations. In a similar study with the sunflower crop, Sousa et al (2016) estimated an index b at 1.0585 for all cultivars tested, thus denoting high soil variability, through the nullity of correlation between the BEUs.…”

“…Sousa et al (2016) state that this argument is incomprehensible when the plot is formed by more than one BEU, since, normally, blank experimentation suggests competition between BEUs or high susceptibility of plants to environmental variations. In a similar study with the sunflower crop, Sousa et al (2016) estimated an index b at 1.0585 for all cultivars tested, thus denoting high soil variability, through the nullity of correlation between the BEUs. Also, in this context, indices b > 1 have been observed in several agronomic studies (Lúcio, Haesbaert, Santos, Schwertner, & Brunes, 2012;Santos, Haesbaert, Lúcio, Storck, & Cargnelutti Filho, 2012;Donato et al, 2018).…”

“…The ideal size of the experimental plot can be established considering soil heterogeneity index -SHI (Smith, 1938;Cargnelutti Filho et al, 2016), genetic material or studied crop (Sousa, Silva, & Assis, 2016), balance between accuracy and costs (Cargnelutti Filho et al, 2016;Sousa et al, 2016), nature of the experimental material, number of replicates and evaluation methods (Cargnelutti Filho et al, 2018).…”

“…These results reinforce the need to plan smaller and more efficient experiments on accuracy and costs. In addition, considering the essence of this method, the researcher can select convenient plot sizes, given the specific objectives, available resources and local conditions of the experimental field (Sousa et al, 2016).…”