Efeito da auxina e do carvão ativado no desenvolvimento da planta de Eucalyptus

Abstract

The use of the Eucalyptus genre wood has a great importance for the forest-based industry, standing out as the main one used in reforestation in Brazil. Studies performed with the use of growth regulators along activated charcoal, stand out as an alternative that can provide improvements in the production and quality of the wood. The objective of this work was to evaluate the influence of foliar application of plant regulator AIA (3-indolyl acetic acid) and activated carbon on the development of Eucalyptus urophylla and E. grandis seedlings. The experiment was conducted in a greenhouse, the plants were cultivated in 12-liter vases in two different types of substrate: one containing three parts of Red Latosol (medium texture) and one part of bovine manure and the other with the same mixture plus the addition of activated charcoal. The regulator applications were performed in a 15 days interval, starting 30 days after the transplanting of the seedlings. The design was completely randomized, in a 3 x 2 factorial scheme, with six treatments and four replications, totalizing 24 experimental plots consisting of one plant per plot, being one experiment conducted for Eucalyptus urophylla and one for E. grandis. The treatments were performed by varying the dosage of hormonal regulator (zero, 5 and 10 milimolar - mM) with and without addition of activated carbon to the substrate. After the transplanting, height data were collected for a period of 15 weeks. After this period, measurements of dry mass of the root system and some anatomical properties (length, width and thickness of fibers) were done regarding 10%, 30% and 50% of total plant height. The results indicate that the plant regulator influenced the development of the analyzed plants, with the lowest dosages being the ones with the best results. The presence of activated charcoal in the soil may mask the effects of the regulator's action on the total height of the seedlings, however, there is a slight increase of dry root mass. The higher AIA dosage promoted the cell stretching and enlargement of the fibers, resulting in long and wide fibers. For the wall thickness, the lower dosage presented an exponential increase of tapering in the base-top direction. However, it is important that studies in longer periods of evaluation are performed, to obtain better results in the use of plant regulator and activated charcoal.