Sample size for evaluating the height and diameter of seedlings pecan/ Dimensionamento amostral para avaliacao de altura e diametro de mudas de nogueira-peca

The aim of this research was to determine the sample size (number of plants) necessary to estimate the average plant height, collar diameter and relation plant height/collar diameter of seedlings pecan (Carya illinoinensis) and to verify the variability of the sample size among treatments of overcoming seed dormancy. It was evaluated 12 treatments of overcoming seed dormancy and at 98 days after sowing it was measured the plant height (H) and collar diameter (D) and calculated the relation plant height/collar diameter (HD). Measures of central tendency and variability were calculated, the normality and homogeneity of variances were verified and sample size was calculated. The sample size to evaluate H, D e HD is dependent on treatments of overcoming seed dormancy. Sixty-three plants enough to predict the average of H, D and HD seedlings pecan, with an estimation error equal to 10% of estimated average, with a degree confidence of 95%. Key words: Carya illinoinensis, experimental planning, sampling. O objetivo deste trabalho foi determinar o tamanho de amostra (numero de plantas) necessario para a estimacao da media de altura de planta, do diametro do coleto e da relacao altura de planta/diametro do coleto de mudas de nogueira-peca (Carya illinoinensis) e verificar a variabilidade do tamanho de amostra entre tratamentos de superacao de dormencia de sementes. Foram avaliados 12 tratamentos de superacao de dormencia de sementes e, aos 98 dias apos a semeadura, foram mensurados os caracteres altura de planta (H) e diametro do coleto (D), e calculada a relacao altura de planta/diametro do coleto (HD). Foram calculadas medidas de tendencia central e de variabilidade, verificadas a normalidade e a homogeneidade de variancias e calculado o tamanho de amostra. O tamanho de amostra para avaliar H, D e HD de mudas de nogueira-peca e dependente do tratamento para superacao de dormencia de sementes. Sessenta e tres plantas sao suficientes para a estimacao da media de H, do D e da HD de mudas de nogueira-peca, para erro de estimacao de 10% da media estimada, com grau de confianca de 95%. Palavras-chave: Carya illinoinensis, planejamento experimental, amostragem.