Chemical analyses of flowers and leaves for nutritional diagnoses of coffee trees / Diagnóstico nutricional do cafeeiro por meio de análise floral e foliar

ABSTRACT: The chemical analysis of flowers has been studied for some crops. In coffee trees, the flower tissue analysis could anticipate the nutritional diagnosis. This study aimed to: (i) compare the mineral composition of coffee flowers and leaves; and to (ii) generate reference values for nutritional diagnosis of coffee trees, based on flower and leaf analysis. Nutrient content of flowers and leaves and coffee productivity were evaluated in 26 commercial farms located in Manhuaçu, MG, Brazil throughout three years. The critical nutrient content range in flowers are respectively: 2.78 - 3.17, 0.23 - 0.28, 2.80 - 3.12, 0.30 - 0.37, 0.24 - 0.30, 0.15 - 0.18 dag kg-1 of N, P, K, Ca, Mg, and S; and 17 - 21, 12 - 18, 52 - 80, 26 - 43, and 28 - 48 mg kg-1 of Zn, Cu, Mn, Fe, and B. For leaves, the critical nutrient ranges are respectively: 2.63 - 2.86, 0.13 - 0.14, 2.13 - 2.33, 1.04 - 1.22, 0.27 - 0.33, 0.15 - 0.18 dag kg-1 of N, P, K, Ca, Mg, and S; and 9 - 14, 15 - 23, 80 - 115, 99 - 148, and 31 - 37 mg kg-1 of Zn, Cu, Mn, Fe, and B. The nutritional diagnosis of coffee trees for N, P, Ca, Fe, Cu, and Mn can be anticipated using flower analysis.

RESUMO: A análise química de flores tem sido estudada em algumas culturas. Para o cafeeiro, a análise do tecido floral possibilitaria a antecipação do diagnóstico nutricional das lavouras. O estudo objetivou (i) comparar a composição mineral de flores e de folhas de cafeeiros (ii) e gerar normas para diagnose nutricional do cafeeiro com base na análise de tecidos de flores e folhas das plantas. Para isso, foram avaliados os teores de nutrientes em flores e folhas e a produtividade de café em 26 lavouras comerciais na região de Manhuaçu, MG, durante três anos. As faixas críticas de nutrientes determinadas em flores são: 2,78 - 3,17; 0,23 - 0,28; 2,80 - 3,12; 0,30 - 0,37; 0,24 - 0,30; 0,15 - 0,18 dag kg-1 de N, P, K, Ca, Mg e S, e 17 - 21; 12 - 18; 52 - 80; 26 - 43 e 28 - 48 mg kg-1 para Zn, Cu, Mn, Fe e B, respectivamente. As faixas críticas de nutrientes em folhas foram: 2,63 - 2,86; 0,13 - 0,14; 2,13 - 2,33; 1,04 - 1,22; 0,27 - 0,33; 0,15 - 0,18 dag kg-1 de N, P, K, Ca, Mg e S, e 9 - 14; 15 - 23; 80 - 115; 99 - 148 e 31 - 37 mg kg-1 para Zn, Cu, Mn, Fe e B, respectivamente. A diagnose nutricional do cafeeiro, quanto aos nutrientes N, P, Ca, Fe, Cu e Mn, pode ser antecipada por meio da análise de flores.

The analytical method of three phenoxyalkanoic acid herbicides in grape leaf by dichloropropyl esterification and gas chromatography / 中国法医学杂志

ObjectiveTo develop a analytical method of three phenoxyalkanoic acid herbicides,MCPA,2,4-D and dichlorprop,in grape leaf using dichloropropyl esterification and gas chromatography with electron-capture detection.MethodsSamples were pounded to pieces,added into internal standard 2,4-dichlorophenylacetic acid,acidified and extracted with ethyl ether.The extracts were cleaned up by liquid-liquid partition.The cleaned organic solutions were evaporated and the residues were dichloropropylated using sulfuric acid and 1,3-dichloropropan-2-ol.The formed esters were analysed by gas chromatography.ResultsThe detection limits of MCPA,2,4-D and dichlorprop in grape leaf were 20ng/g,20ng/g,and 30ng/g,respectively.The concentritions of herbicides in grape leaf were linear over the ranger 100~1000ng/ml.The average recoveries of MCPA,2,4-D and dichlorprop in spiked grape leaf at concentrition of 200ng/g were 98.8%,101.3% and 103.1% with the coefficients of variation 11.4%,11.0% and 9.3% respectively.ConclusionThis method is sensitive and accurate for determination of these three herbicides in poisoned grape leaf.