A precisão do tamanho ideal da amostra foliar determina a otimização de mão-de-obra, e diminui erros inerentes ao
laudo de diagnose do estado nutricional. Com este trabalho se objetivou determinar, em pomares de goiabeira submetidos
a dois regimes hÃdricos, o tamanho de amostras foliares e a variação do erro amostral para a diagnose do estado
nutricional dessa frutÃfera. O respectivo trabalho contou com o emprego de dois estudos, ambos sob um delineamento
experimental inteiramente casualizado, sendo: Estudo 1: Realizado em pomar sob regime não irrigado, com quatro tratamentos
e seis repetições, que constaram da coleta de folhas em 5, 10, 20 e 40 plantas. Estudo 2: Realizado em pomar
sob regime irrigado, com cinco tratamentos e dez repetições, que constaram da coleta de folhas em 10, 20, 30, 40 e 50
goiabeiras. Concluiu-se que em pomares não irrigados é necessário amostrar folhas em 40 plantas, a fim de manter o
erro amostral de macronutrientes entre 5 a 10%; já para os micronutrientes seriam necessárias, no mÃnimo, 40 plantas e,
se considerados o Fe e o Zn, a amostra deverá ser maior. Em pomares irrigados folhas provenientes de 10 plantas seriam
suficientes para manter o erro amostral entre 5 e 10%; considerando-se, porém, os micronutrientes, seriam necessários
amostrar 20 goiabeiras.
The ideal size precision of the foliar sample determines manual work optimization, and also diminishes inherent errors
in diagnosis reports of nutritional state. This work aimed to determine the size of the foliar samples and the sample error
variation in guava plantations submitted to two hydric cultivations for the nutritional state diagnosis of this fruit. The
work included two studies, both under an entirely randomized experimental design. Study 1 was carried out in an orchard
under unirrigated cultivation with four treatments and six repetitions that consisted of leaf collection in 5, 10, 20 and 40
plants. Study 2 was carried out in an orchard under irrigated cultivation with five treatments and 10 repetitions that
consisted of leaf collection in 10, 20, 30, 40 and 50 guava plants. It was concluded that in unirrigated orchards it is
necessary to sample leaves in 40 plants in order to keep the macronutrients sample error between 5 to 10%. For the
micronutrients, on the other hand, at least 40 plants were necessary and, if Fe and Zn were considered, the sample must
be even larger. In irrigated orchards, leaves deriving from 10 plants were enough to keep the sample error between 5 to
10%. However, considering the micronutrients, it was necessary to sample 20 guava plants.
