Absorção e translocação de silício em mudas de eucalipto cultivadas em latossolo e cambissolo

Abstract

With the objective of studying the absorption and the translocation of Si by seedlings of Eucalyptus grandis W. Hill. Ex Maiden cultivated in samples of a dystrophic Red Latosol (Oxisol) and of a dystrophic Haplic Cambisol (Inceptisol), two experiments were carried out under greenhouse conditions. Each soil was submitted to three sequencial incubations for the application of the treatments: a) CaCO3+MgCO3 to maintain the pH around 6.0; b) basic fertilization with macro and micronutrients; c) six doses of Si (CaSiO3). The plants were grown in pots containing 2.7 dm3 of soil. The water-soluble Si in the soil and the Si content in the plant roots and shoot were evaluated at 60, 90, and 120 days after seedlings transplanting. Response surfaces for those variables were adjusted as a function of the Si doses and evaluation epoch. The indices of uptake and use efficiency of the Si by plants and the percentage of translocated Si were determined. In the initial growth phase (60 days), the seedlings absorbed very little amounts of Si. The translocation efficiency was highest at 60 days, being most of the element retained in the roots after that time. The amount of water-soluble Si in the soil was reduced with the time, but the uptake of the element by the Eucalyptus was not related to this fact. The obtained data evidenced the Eucalyptus is a non-accumulator plant, although responsive to Si.