Estudou-se a absorção e o acúmulo de macronutrientes pela estévia, em condições de cultivo comercial no campo. Foram avaliados dois índices nutricionais: Taxa de Absorção Relativa do Nutriente e Taxa de Acumulação Líquida Organogênica do Nutriente. Foram realizadas 7 coletas a cada 15 dias a partir do transplante. Pouco antes ou no início do florescimento, a produção de 1 tonelada de folhas secas exigiu, em kg: N-64,6; P-7,6; K-56,1; Ca-15,8; Mg-3,6 e S-3,6. Para a produção de sementes, correspondente a 1 tonelada de folhas secas, a extração de macronutrientes, em kg, foi: N-130; P-18,8; K-131,5; Ca-43,7; Mg-8,3 e S-9,7.
Uptake and accumulation of macronutrients by stevia were studied under field conditions. Two nutritional indices were evaluated: Nutritional Relative Absorption Rate and Nutritional Organogenic Net Accumulation Rate. Seven samplings with fortnight intervals were made beginning after transplanting. Shortly before or at flowering the production of 1 ton of dry leaves demands, in kg: N-64.6; P-7.6; K- 56.1; Ca -15.8; Mg-3.6 and S-3.6. For seed production corresponding to 1 ton of dry leaves, the extraction of macronutrients in kg, is: N-130; P-18.8; K-131.5; Ca-43.7; Mg-8.3 and S-9.7
Remobilization and re-utilization of 15N and 85Rb labelled nitrogen and potassium reserves for new growth and fruit formation was studied under greenhouse conditions using both normal and deficient young coffee plants. It was found that K reserves are used in higher proportion than is stored N by fruits and other organs. The export of N by organs of residence in the normal plants obeyed the following proportions of the total: leaves 47%-58%, branches and flower buds 21%-27%, roots 21%-32%. The corresponding figures in the case of deficient plants were: leaves 49%-65%, branches and flower buds 21%-27%, roots 14%-25%. Re-utilization of K took place in the following proportions in the normal plants: leaves 54%-64%, branches and flower buds 20%-21%, roots 30%-41%. In K deficient plants the figures were: leaves 62%-79%, branches and flower buds 1.2%-4.4%, roots 20%-33%. In tissues formed after the initiation of flowering buds, the demand for N is met by reserves as follows: normal plants: fruits 20.6%-24.8%, leaves 15.6%-19.4%, twigs 19%-20.5%; deficient plants: fruits 43.5%-48.5%, leaves 48.1%-51.9%, twigs 46%-53%. The K needs for new tissues are met in the order: normal plants: fruits 40%-45.8%, leaves 27%-37.6%, twigs 26%-33.1%; deficient plants: fruits 65.7%-81.5%, leaves 52.6%-68.4%, twigs 62%-86.1%. Fruits represent the main sink for both N and K. Re-utilization of both elements is higher in the case of deficient plants.
Foi conduzido em casa de vegetação um experimento com o objetivo de avaliar o efeito de fontes de enxofre, na presença ou não de aditivos (uréia e glicose), sobre a absorção do demento pelas folhas de feijoeiro. Os tratamentos: soluções de ácido sulfúrico e de sulfates de amonio, potássio, magnésio, manganês e zinco marcadas com 35S, contendo ou não os aditivos, foram aplicados ao primeiro trifólio das plantas para avaliar a absorção e translocação de enxofre. Os resultados permitiram concluir que 33% do S adicionado foi absorvido, e desse total 27% foi translocado, não havendo influência dos aditivos sobre esses processos. O ácido sulfúrico e o sulfato de amonio destacaram-se como os melhores fornecedores de enxofre, via foliar, para o feijoeiro.
Estudou-se a absorção e o acúmulo de micronutrientes pela estévia, em condições de cultivo comercial no campo. Foram avaliados dois índices nutricionais: Taxa de Absorção Relativa do Nutriente e Taxa de Acumulação Líquida Organogênica do Nutriente. Foram realizadas 7 coletas a cada 15 dias a partir do transplante. Pouco antes ou no início do florescimento, a produção de 1 tonelada de folhas secas exigiu, em g: B-89; Cu-26; Fe-638; Mn-207; Zn-13. Para a produção de sementes, correspondente a 1 tonelada de folhas secas, a extração de micronutrientes, em g, foi: B-226; Cu-76; Fe-2550; Mn-457; Zn-33.
Uptake and accumulation of micronutrients by stevia were studied under field conditions. Two nutritional indices were evaluated: Nutritional Relative Absorption Rate and Nutritional Organogenic Net Accumulation Rate. Seven samplings with fortnight intervals were made beginning after transplanting. Shortly before or at flowering the production of 1 ton of dry leaves demands, in g: B-89; Cu-26; Fe-638; Mn-207; Zn-13. For seed production corresponding to 1 ton of dry leaves, the extraction of micronutrients, in g, is: : B-226; Cu-76; Fe-2550; Mn-457; Zn-33
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