Proposta de método para estimação de tamanho de parcela para culturas agrícolas

Abstract

Proposal method for plot size estimation in cropsOptimum plot size for the application of treatments is among the recognized methods to reduce the experimental error. There are several methods for plot estimation based on different principles. The objective of this paper was to propose an alternative method for the estimation of optimum plot size for crops, compare it with classical methods and to identify which parameters their results are correlated with. Fruit yield data from four experiments with sweet pepper cultivated in a greenhouse were used to validate the proposed method. It was evaluated the yield accumulated in several harvests. The results obtained by the proposed method, denominated Maximum Distance Method, are consistent, but weakly associated with the results obtained by other classical methods. The optimal plot size estimated by the Maximum Distance Method is strongly influenced by the heterogeneity index of production that measures the correlation between the productions in contiguous plots. It still has the characteristics of being easy to apply, remains practically unchanged in the cumulative productions, adapting to crops with two or more harvests in the same plants, as in vegetable crops or forage experiments. Proposta de método para estimação de tamanho de parcela para culturas agrícolasDentre as formas reconhecidas para redução do erro experimental, destaca-se o tamanho ótimo da parcela experimental para aplicação dos tratamentos, existindo vários métodos para sua estimação, baseados em diferentes princípi-os. O objetivo deste trabalho é propor um método alternativo para a estimação do tamanho ótimo de parcela, para culturas agrícolas, compará-lo com métodos clássicos para esse fim e identificar com quais parâmetros seus resultados estão correlacionados. Realizou-se a validação dos resultados, utilizando-se dados de quatro experimentos com plantas de pimentão, em que se avaliou a produção de frutos, acumulada nas várias colheitas, cultivado em estufa com cobertura plástica. Os resultados obtidos pelo método proposto, denominado Método da Máxima Distância, são coerentes, mas fracamente associados aos resultados observados pelos demais métodos clássicos. O tamanho ótimo da parcela, estimado pelo Método da Máxima Distância, é fortemente influenciado pelo índice de heterogeneidade da produção, que mede a correlação entre as produções de parcelas contíguas. Há, ainda, as características de ser de fácil aplicação, praticamente invariável à acumulação da produção em diversas colheitas, adequando-se para culturas com duas ou mais colheitas nas mesmas plantas, como em experimentos com culturas olerícolas ou forrageiras.Palavras-chave: precisão experimental, planejamento de experimentos, índice de heterogeneidade, Capsicum annuum L., colheitas múltiplas. 773Proposta de método para estimação de tamanho de parcela para culturas agrícolas Rev. Ceres, Viçosa, v. 59, n.6, p. 772-780, nov/dez, 2012

Optimal plot size in the evaluation of papaya scions: proposal and comparison of methods

“…using the modified maximum curvature method (Meier & Lessmam, 1971). This relationship, also was reported by Lorentz et al (2012), and it can also be verified in the proposed method; however, the values are close to 0.500 and the b values are close to 1.000. Considering that Smith's b values (1938) range from zero to one and that values closer to one indicate heterogeneity in crop environment, it is clear that the method proposed by bootstrap simulation is valuing the maximum of heterogeneity.…”

Optimum plot size for experiments with papaya genotypes in field

“…Many methods have been assessed with this aim, either from blank test (Meier and Lessman, 1971;Paranaíba et al, 2009;Lorentz et al, 2012) or from experiments involving analyses of variance (Pimentel-Gomes, 1984;Lin and Binns, 1984;Barbosa et al, 2001). The method proposed by Lin and Binns (1984) is used to estimate intra-block correlation and heterogeneity index, which is easier to perform than the methods involving blank assays.…”

Estimation of optimal size of plots for experiments with radiometer in beans

“…The method of maximum distance was then calculated, where its resolution of the geometry formed by ayc curve, described by CVx=aX , and a secant line to this curve, yr. We look for the point of the curve yc that is at the largest distance from the line yr, since the line segment along this distance is perpendicular to the line yr (Lorentz et al, 2012).The solution method presented by Lorentz et al (2012) proposes to express the line perpendicular to the line yr as an aid to find the point sought of the yc curve. So, this line perpendicular to the line yr will be called the yp, expressed by yp=ex+f.…”

“…To plan the tests and assess the magnitude of the experimental accuracy is important to determine the level of credibility of the results obtained in the research (Storck, 2011;Storck et al, 2011). The establishment of optimum plot size, in any culture, is one of the ways to increase the experimental precision and maximize the information obtained in an experiment (Silva et al, 2012), and is a recognized way to reduce experimental error, while there are several methods for its estimation based on different principles (Lorentz et al, 2012).The experimental error, which is the existing variance between experimental units that received the same treatment, is estimated by applying repetition, which is one of the principles of the trial and to avoid it is necessary to know the characteristics of the experimental area and the grown culture (Oliveira et al, 2005). Works with the right size of plots allow optimal use of resources, while also allowing the researcher greater control and management of their experiment, when performed in a smaller area (Lackey and Stein, 2014).For determining the optimum plot size through the method of maximum modified curvature and the maximum distance method a blank experiment is necessary, with the culture of interest and then the experimental area is subdivided into smaller portions, called basic units from which the data is collected independently while identifying the relative position.…”

“…Works with the right size of plots allow optimal use of resources, while also allowing the researcher greater control and management of their experiment, when performed in a smaller area (Lackey and Stein, 2014).For determining the optimum plot size through the method of maximum modified curvature and the maximum distance method a blank experiment is necessary, with the culture of interest and then the experimental area is subdivided into smaller portions, called basic units from which the data is collected independently while identifying the relative position. After the taking of the data, plots of different sizes and shapes are simulated through the sum of contiguous plots (Lorentz et al, 2012).…”