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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.1979.tde-20220208-000004
Document
Author
Full name
Paulo César Lima
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1979
Supervisor
Title in Portuguese
Método de amostragem para a avaliação do índice de infecção da ferrugem do cafeeiro (Hemileia vastatrix Berk. e Br.)
Keywords in Portuguese
AMOSTRAGEM
CAFÉ
EPIDEMIOLOGIA
FERRUGEM
FUNGOS FITOPATOGÊNICOS
Abstract in Portuguese
O objetivo principal do presente trabalho foi a determinação de planos alternativos de amostragem para avaliação de índices de infecção da ferrugem do cafeeiro (Hemileia vastratrix Berkeley e Broome) e, ao mesmo tempo, efetuar uma análise crítica do método de amostragem comumente empregado. Para isto, foram utilizadas 24.000 amostras de cinco folhas cada, coletadas em duzentas plantas de cafezal "Piloto" da Escola Superior de Agricultura de Lavras. As amostras foram tomadas nos terços inferior, médio e superior das plantas, sendo deter minado o número de pústulas da ferrugem por amostra. Os dados foram transformados para raiz quadrada. Para as análises estatísticas, foi admitido o modelo matemático de Classificação Hierárquica: yijk = µ + pi + poij + fijk. Os efeitos relativos a "Plantas" (pi) e "Entre Amostras dentro de Posições" (fijk), foram considerados aleatórios. Com os quadrados médios da Análise, foram estimados os componentes de variância, verificando-se que a variação "Entre Amostras" foi muito maior do que a variação "Entre Plantas". Para a comparação de diferentes tamanhos de amostras (diferentes números de folhas por planta e diferentes números de plantas por amostra), estimou-se a variância da média para cada tipo de amostra. Também foram comparadas as variâncias das médias amostrais com a determinada para a amostra usual, ou seja, constituída de dez folhas por planta e dez plantas. As precisões das estimativas foram comparadas através dos coeficientes de variação, verificando-se que a precisão foi maior com o aumento da amostra. Para a determinação do tamanho ótimo da amostra foi desenvolvida uma expressão com base na Amostragem Hierárquica a dois estágios e considerados os custos de amostragem. Os resultados mostraram que a amostra ótima, fixada uma precisão de 5% da média, foi constituída por cinco folhas por planta e quarenta e sete plantas, a qual apresentou uma variância 68% inferior à obtida para o método de amostragem comumente empregado.
Title in English
Not available
Abstract in English
The main objective of this paper was to settle alternative schemes of sampling to evaluate the ratio of infection by the leaf rust (Hemileia vastatrix, Berkeley and Broome) at the coffee plantation, and the same time make e critical analysis of the sampling method normally used. For this, there were collected 24.000 samples of five leaves each, picked out of 200 coffee trees ant the "Piloto" coffee plantation at ESAL, Lavras. The samples were taken from the lower, medium and upper parts of the tress and than the number of pustule of leaf rust was determined in each sample. The data were transformed to square roots. For statistical analysis, were admitted the mathematical model of Nested Sampling: yijk = µ + pi + poij + fijk. The effects related to "Plants" (pi) and "Between Samples within Positions" (fijk), were considered random effects. The components of variance were estimated by mean squares and it was found that the variation between samples was much greater than the variation between plants. In order to compare different sizes of samples (differents number of leaves for plant and different number of plants for sample), the variance of the sample mean was estimated for each kind of sample. The variances of the sample means were compared with the variance obtained from the usual sample (ten leaves from each plant and ten plants). The precision of the estimatives were compared by the coefficient of variation and it was found that the precision was greater with the increasing of the sample size. To determinate the optimum sample size it was derived equation based on the Nested Sampling at two stages, and the sample costs were also considered. The results indicated that optimum sample for a fixed precision of 5% of the mean, was the sample of five leaves from each plant and forty seven plants. The variance of this sample was 68% lower than the variance of the sampling method most used.
 
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