Amostragem para diagnose do estado nutricional de mangueiras

Abstract

RESUMO -Dentre todas as etapas que permeiam um laudo foliar, ainda a amostragem continua sendo a mais sujeita a erros. O presente trabalho teve como objetivo determinar o tamanho de amostras foliares e a variação do erro amostral para coleta de folhas de pomares de mangueiras. O experimento contou com delineamento inteiramente casualizado, com seis repetições e quatro tratamentos, que constaram da coleta de uma folha, em cada uma das quatro posições cardeais, em 5; 10; 20 e 40 plantas. Com base nos resultados dos teores de nutrientes, foram calculados as médias, variâncias, erros-padrão das médias, o intervalo de confiança para a média e a porcentagem de erro em relação à média, através da semi-amplitude do intervalo de confiança expresso em porcentagem da média. Concluiu-se que, para as determinações químicas dos macronutrientes, 10 plantas de mangueira seriam suficientes, coletando-se uma folha nos quatro pontos cardeais da planta. Já para os micronutrientes, seriam necessárias, no mínimo, 20 plantas e, se considerarmos o Fe, seria necessário amostrar, pelo menos, 30 plantas. Termos de indexação: diagnose foliar, Mangifera indica, nutrição mineral SIZE OF SAMPLES FOR NUTRITIONAL STATUS ASSESSMENT OF MANGO TREESABSTRACT -Of all the processes used in foliar evaluation, sampling is currently still the most subject to error. To corroborate this, the present study aimed to determine the size of foliar samples and error variation of samples collected from mango tree leaves. The study used a completely randomized design with six repetitions and four different treatments which consisted of a leaf from each of the cardinal points from 5, 10, 20 and 40 different trees. Mean variation, mean standard error, mean confidence interval and error percentage compared to mean values were calculated based on level of nutrients. Results were calculated by using the semi-amplitude of the interval of confidence expressed as mean percentages. Obtained results led to the conclusion that the chemical evaluation of macro-nutrients from 10 mango plants would be sufficient for assessment. However, for assessment of micro-nutrients, the sampling of 20 plants would be necessary, and, when considering Fe, a total of 30 plants should be used.

Heavy metals in soils and plants in mango orchards in Petrolina, Pernambuco, Brazil

“…Only in the areas after 7 and 19 years of cultivation, the Mn contents were within the range considered adequate (Quaggio, 1996), while in all other orchards the values were clearly higher than the adequate level. Similar results of Mn excess in the mango leaves were also reported by Assis et al (2004), Rozane et al (2007), Pinto et al (2009), andGalli et al (2009). The high levels may be explained by the high Mn concentration in the soil and by spraying with Mn-based chemical products to control pests and diseases.…”

Changes in soil fertility and mineral nutrition of mango orchards in São Francisco Valley, Brazil

“…Low values of Mg in the leaves of mango trees were also found by Assis et al (2004), Rozane et al (2007) and Galli et al (2009). This element is part of the chlorophyll molecule and is an activator of various enzymes, in addition to being essential for the absorption of P. However, its absorption is inhibited by high concentrations of K in the plant (Magalhães & Borges, 2000), which could have occurred in the plants in this study, since large amounts of K were found in the leaves.…”

Nutrient Contents in ‘Tommy Atkins’ Mango Leaves at Flowering and Fruiting Stages

“…Values higher than those of reference were found by ROZANE et al (2007) when evaluating the size of sample in mango leaf. According to COSTA et al (2011), nitrogen may suffer temporary changes due to the fertilization.…”