Crescimento e nutrição de clone de eucalipto em função da aplicação de c-ácidos húmicos

• Autor(a) principal: Pinheiro, Gabriela Lúcia
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFLA
• Texto Completo: http://repositorio.ufla.br/jspui/handle/1/2415
• topic: Substâncias húmicas; Ácidos húmicos; Ácido cítrico; Ácido oxálico; CNPQ_NÃO_INFORMADO

The humic substances regulate the plant growth since they provide greater accumulation/absorption of nutrients and stimulate the root growth. This study was carried out to evaluate the effects of humic acid doses on eucalyptus seedlings nutrition and growth. The experiment was conducted in nutrient solution under greenhouse conditions, at the Department of Soil Science/UFLA. The treatments consisted of two sources of humic acids (humic material and humic acid p.a.) and each source was added in four carbon doses, in the form of humic acid (0, 10, 30 and 150 mg L-1). Other treatments were applied using the source humic acid p.a. (HA p.a.) in doses of 0, 10, 30 and 150 mg L-1 C-humic acid, combined with 100 μmol L-1 citric acid (CA) and 100 μmol L-1 of oxalic acid (OA). It was analyzed the following variables: electric conductivity of nutrient solution, the stem diameter and height of plants, weight of dry matter of stem (SDM), leaves (LDM), shoot (SDM), root (RDM) and total (TDM), RDM:SDM ratio and the SDM:LDM ratio, accumulation of nutrients in the SDM and LDM. The application of increasing doses of C-humic acid resulted in a decrease in the biomass production and in the accumulation of nutrients. For the humic material (HM) doses, the reduction in the nutrient accumulation and in the biomass were less expressive, but occurred in superior doses of 30 mg L-1 C-humic acid. The addition CA and OA of increased the accumulation of the majority of the cationics nutrients, mainly Fe, in the SDM and LDM, and Zn, in the LDM. The nutrients accumulate preferentially in higher rates in the leaves, compared to the stem, except for K accumulation. The HM affected the root/shoot dry matter ratio, especially in higher doses of C-humic acid, since the root growth, proportionally, was higher than the shoot counterpart.