RESUMOCrescimento, produção e tamanho de grãos de café decorrentes de doses de N e K em solução nutritiva O suprimento adequado de nutrientes ao cafeeiro é essencial para obtenção de alta produtividade. O objetivo deste trabalho foi avaliar o efeito do nitrogênio, do potássio e da relação N:K no crescimento vegetativo e reprodutivo do cafeeiro. Para isto, plantas de café receberam solução nutritiva, contendo K nas concentrações de 1,08; 2,15; 3,23 e 5,38 mmol L -1 , combinadas com a dose de 6 mmol L -1 de N, obtendo-se as relações N:K (p/p):1,0:0,5; 1,0:1,0; 1,0:1,5; 1,0:2,5. O tratamento controle continha as doses de 3 e 1,61 mmol L -1 de N e K, respectivamente, resultando na relação N:K (p/ p) de 1,0:1,5. Avaliaram-se a altura, o diâmetro do caule, número de nós do oitavo ramo plagiotrópico (ramo índice), o número de pares de ramos plagiotrópicos e o número de nós do ramo ortotrópico a cada três semanas após o início do experimento. Realizaram-se também análises da composição química dos grãos beneficiados e folhas, no período entre a floração e expansão rápida dos frutos, produção de café cereja por planta e classificação dos grãos quanto ao tamanho. O N influenciou principalmente as características de crescimento vegetativo e o K influenciou principalmente as características de crescimento reprodutivo, avaliadas pela produção. A menor produção resultou em percentagens mais elevadas de grãos retidos nas peneiras com crivos maiores que 16/64 polegadas, enquanto a maior produção promoveu aumento na percentagem de grãos retidos nas peneiras com crivos menores que 16/64 polegadas.Palavras-chave: crescimento, produção, Coffea. Received: 29/12/2011; Accepted: 08/02/2013 Effect of N and K doses in nutritive solution on growth, production and coffee bean sizeAn adequate supply of nutrients is essential for obtaining high yields of coffee. The objective of this study was to evaluate the effect of N, K and the N:K ratio on vegetative and reproductive growth of coffee. For this purpose, coffee plants were grown in nutrient solution containing K in the concentrations of 1.08; 2.15; 3.23 and 5.38 mmol L -1 combined with a dose of 6 mmol L -1 N, resulting in the N:K ratios (w/w): 1:0.5; 1:1; 1:1.5 and 1:2.5. The control treatment consisted of the doses 3 and 1.61 mmol L -1 of N and K respectively, resulting in the N:K ratio (w/w) 1.0:1.5. The following variables were evaluated: height, stem diameter, number of nodes of the eighth plagiotrofic branch (index branch), pairs of plagiotrofic branches and number of nodes in the orthotropic branch every three weeks from the beginning of the experiment. Additionally, it was evaluated the chemical composition of processed beans and leaves between the flowering and the rapid expansion stage of the cherry beans, production of cherry beans per plant and classification of beans according to the size. N influenced mainly the characteristics of vegetative growth and K influenced mainly the reproductive growth evaluated by the production. The lowest production resulted in the hig...
This study aimed to optimize and validate an analytical method for extraction, detection, and quantification of haloxyfop-methyl, procymidone, and linuron pesticides in carrot samples using solid-liquid extraction methods and low temperature partition (SLE-LTP), accompanied by gas chromatography coupled to mass spectrometry (GC-MS). For SLE-LTP technical optimization, we utilized a complete factorial planning, which had as its variables, agitation time, freezing time, and the correct sample mass/extracting solution volume ratio. The organic extract obtained was analyzed by GC-MS. To test the performance of this procedure, the method was validated and applied to the monitoring of pesticide residues in 20 samples of carrot produced in Alto Paranaíba, Minas Gerais, Brazil. The proposed method showed linearity between 0.5 and 3.5 mg·kg −1 with correlation coefficients greater than 0.99. The quantification limits were 0.48 mg· kg −1 for haloxyfop-methyl, 0.69 mg·kg −1 for linuron, and 0.65 mg·kg −1 for procymidone, values below the maximum residue limit provided by international legislation of 1.0 mg· kg −1 for linuron and procymidone. The use of haloxyfopmethyl is not approved in the cultivation of carrot. The recovery percentages were between 90 and 110 %, with a coefficient of variation of less than 12 %. Ten percent of the carrot samples monitored showed residues of linuron and procymidone in concentrations exceeding those permitted by Brazilian law.
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