Índice de heterogeneidade, coeficiente de variação e tamanho ótimo de parcela em batata

Oliveira, Sérgio José Ribeiro de; Storck, Lindolfo; Lúcio, Alessandro Dal ́Col; Lopes, Sidinei José; Martini, Luiz Fernando Dias

doi:10.1590/s0103-84782006000600007

Cited by 19 publications

(16 citation statements)

References 9 publications

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“…A estimativa do tamanho ótimo, pelo método da Máxi-ma Curvatura Modificado (MCM), mostrou-se fortemente associada à variabilidade da produção da cultura, refletida pela estimativa do coeficiente de variação (A), com correlação de 0,99, corroborando a magnitude da associação encontrada por Storck et al (2006a) e Oliveira et al (2006), para as culturas do milho e batata, respectivamente. No entanto, os resultados encontrados contrariaram os relatos, dos mesmos autores, em relação ao índice de heterogeneidade da produção, pois a correlação encontrada por eles foi positiva e alta entre esses atributos e, neste caso, foi negativa e não significativa (r MCMxb = -0,284).…”

Section: Resultsunclassified

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

2012

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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

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Section: Resultsunclassified

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

2012

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“…Optimum plot size (Xo) varies between four and six hills, with an average of five hills per plot. The values of the yield heterogeneity index (b) that correspond to two times estimate B (OLIVEIRA et al, 2006), vary in the intermediate range (b between 0.456 and 0.687), values in which the correlation between neighboring plots is moderate and considered to be an adequate situation for planning experiments, simultaneously varying the number of replications and the plot size (LIN & BINNS, 1986).…”

Section: Resultsmentioning

confidence: 99%

“…Considering that optimum plot size (point of maximum curvature of the function) is influenced more by the value of A than by the value of B (OLIVEIRA et al, 2006), despite the fact that the correlation between A and B is linear, positive and significant, the value of Xg will depend only on the values of SP and J within the same lot of experimental units under evaluation. In this methodology, the yield heterogeneity index or correlation between neighboring plots estimated in function VU(x)=V1/X b , proposed by SMITH (1938), that can be estimated as b=2B (OLIVEIRA et al, 2006) has less influence on the magnitude of Xg, although it is in the same direction.…”

Section: Resultsmentioning

confidence: 99%

“…In this methodology, the yield heterogeneity index or correlation between neighboring plots estimated in function VU(x)=V1/X b , proposed by SMITH (1938), that can be estimated as b=2B (OLIVEIRA et al, 2006) has less influence on the magnitude of Xg, although it is in the same direction. Thus, what most influences optimum plot size is the estimate of the coefficient of variation between the plots of one basic unit, added to the number of replications and the predefined selective precision.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, methodologies and applications to estimate the optimum plot size (SMITH, 1938, MEIER & LESSMAN, 1971LOPES et al, 2005;OLIVEIRA et al, 2006;BRUM et al, 2008) are based on the non-linear relation CV(x)=A/X B , where CV(x) are the variation coefficients for plots planned at different sizes (X), expressed as a number of basic units. The point of maximum curvature (Xo) of the function CV(x)=A/X B is considered to be the optimum plot size (MEIER & LESSMAN, 1971).…”

Section: Introductionmentioning

confidence: 99%

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Optimum plot size and number of replications related to selective precision

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A sampling procedure for quantifying mites in soybeans

et al. 2012

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To control phytophagous mites on soybean crops in an economically viable way, it is necessary to quantify the occurrence of the mites on the leaflets. Estimating the number of mites cm(-2) on leaflets is more difficult because of their irregular distribution on the leaflet surface. Therefore, the aim of this study was to determine the count-area/leaflet and the number of soybean leaflets to quantify the mites. One hundred infested plants were randomly collected. One leaflet was removed from each plant and divided into 32 sections (1.0 cm(2) per section), arranged in four columns and eight rows, to count the mites (adults, nymphs and eggs). The ideal count-area size per leaflet (Xo) was estimated by the maximum curvature of the coefficient of variation method for each of the 100 leaflets. For a count-area of Xo size, we obtained the number of mites cm(-2) per leaflet and, using the bootstrap resampling method, we estimated the point and interval averages as well as the sample size for a pre-established error. We suggest that the determination of the evaluated area size on each soybean leaflet (20 cm(2) in this case) and the bootstrap resampling estimate of the appropriate number of leaflets (12 in this case) for a bootstrap confidence interval of four mites (adults + nymphs) cm(-2) is sufficient to standardize the sampling-procedures for quantifying mites on soybean leaflets.

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Índice de heterogeneidade, coeficiente de variação e tamanho ótimo de parcela em batata

Abstract: Palavras-chave: Solanum tuberosum L., índice de h e t e r o g e n e i d a d e , p l a n e j a m e n t o experimental, precisão experimental. ABSTRACT

Cited by 19 publications

References 9 publications

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

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

Optimum plot size and number of replications related to selective precision

A sampling procedure for quantifying mites in soybeans

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