Faixas de suficiência para teores foliares de nutrientes em algodão e em soja, definidas em função de índices DRIS

Abstract

Sufficiency range for nutrient concentration in cotton and soybean leaves, defined through DRIS indexesNutritional status diagnosis of cotton and soybean crops through critical level methods is based on sufficiency ranges established many years ago, with little advances since then. However, as nutrient contents in leaves are influenced by sample type and crop yield potential among other factors, it is important to establish regional reference values. The aim of this study was to establish optimum nutrient concentrations in cotton and soybean leaves by adjusting a regression model to nutrient concentration based on DRIS indexes. Database consisted of yield and nutrient content in leaf samples collected in commercial cotton and soybean crops and soybean experimental plots in A diagnose dos estados nutricionais do algodoeiro e da soja, pelo método de níveis críticos, tem-se embasado em faixas de suficiência estabelecidas há muitos anos, com pequenas adequações no período. Contudo, considerando-se que os teores foliares podem variar, dentre outros fatores, em função do tipo de amostra coletada e do potencial produtivo da cultura, torna-se importante a definição de valores de referência regionais. Este trabalho teve como objetivo estabelecer os teores adequados de nutrientes para algodoeiro e soja, por meio do ajuste de modelos de regressão para o teor foliar em função do índice de equilíbrio nutricional definido pelo Sistema Integrado de Diagnose e Recomendação (DRIS). Utilizou-se um banco de dados, constituído das produtividades e dos teores de nutrientes em amostras foliares de ambas as espécies, coletadas em talhões de lavouras comerciais e em parcelas experimentais, em Mato Grosso do Sul e Mato Grosso. Foram obtidas faixas de suficiência para as folhas índice de algodoeiro (quinta folha totalmente formada, a partir do ápice) e de soja (terceiro trifólio sem e com pecíolo), com amplitude menor do que aquela estabelecida na literatura para estas culturas. Especificamente, para a soja, confirmou-se a existência de diferenças nos valores de referência em função do tipo de folha índice amostrado. Amostras de folha índice sem pecíolo produzem teores significativamente maiores de N, P, B, Fe, Mn e Zn e menores de K, em relação aos das amostras com pecíolo. A desconsideração do modo de amostragem pode induzir a falsos diagnósticos de deficiências ou excessos nutricionais.Palavras-chave: análise foliar, sistema integrado de diagnose e recomendação, folha índice, Glycine max, Gossypium hirsutum.

Diagnosis of the Nutritional Status of Garlic Crops

“…The range similarity of the DRIS and CND methods and reduction in the amplitude of adequate contents in relation to official norms were also observed by Camacho et al (2012), Kurihara et al (2013), Santos et al (2013a) and Partelli et al (2014). Lower amplitude in the adequate ranges is highly desirable, because it increases distinction between balanced and unbalanced crops.…”

“…It was noted that even for those nutrients where the R 2 of the fitted models was low the linear fit was highly significant (p<0.01). Low R 2 were also observed by Kurihara et al (2013). Similarly, all authors fitted highly significant models for their relationships, and were successful in determining the sufficiency ranges.…”

“…The high yield fields were those with yield above 18,500 kg ha -1 and low yield was below this value. The limit yield (18,500 kg ha -1 ) was the average yield plus two-thirds of the standard deviation of the sampled fields, as proposed by Urano et al (2007) and Kurihara et al (2013).…”

Normal nutrient ranges and nutritional monitoring of 'Pêra' orange trees based on the CND method in different fruiting stages

“…In contrast, optimum nutrient contents corresponding to ±SD and ±⅔SD of the nutritional indices of the nutritionally balanced population, using DRIS and CND, have already been estimated for mango trees (Politi et al, 2013), cotton plants (Serra et al, 2010;Kurihara et al, 2013), coffee trees (Partelli et al, 2007), and guava plants (Souza et al, 2013), with higher amplitudes than those estimated by CI, but lower amplitudes than the sufficiency ranges (SR) proposed in traditional calibration tests (Quaggio et al, 2005).…”

“…The collection was rigorously standardized, since the leaf patterns differ according to the type of the leaf samples (Kurihara et al, 2013). The samplings were performed on the sides of the trees facing the four cardinal points, and always at medium plant height, as recommended by Quaggio et al (2005).…”