INITIAL GROWTH OF SEEDLINGS OF Eucalyptus dunnii Maiden AS INFLUENCED BY THE ADDITION OF NATURAL POLYMER AND FARMING SUBSTRATES

ABSTRACT This study aimed to test different concentrations of natural polymer combined with different substrates in order to maximize the production and quality of Eucalyptus dunnii Maiden as well as the influence of the physical and chemical properties of the substrates. Experiments were conducted in a greenhouse in a randomized design with a 4 x 4 factorial arrangement for different substrates (factor "A") and water-retaining polymer concentrations (factor "B"). The physical and chemical properties of the substrates were also analyzed in each treatment. The seedlings height (H), neck diameter (D), shoot dry matter (SDM), root dry matter (RDM), total dry matter (TDM), H/D ratio and Dickson quality index (DQI) were measured after 90 days of sowing. Both the physical and chemical properties of the substrates have improved by the addition of hydrogel, especially those regarding to porosity, water availability and water holding capacity. In general, the water-retaining polymer concentrations of 2 and 4 g L-1 provided a better seedling growth. Seedlings largest neck diameter was observed at a hydrogel concentration of 6 g L-1. The use of hydrogel has resulted in higher height and neck diameter values when carbonized rice hulls were used as substrate. Therefore, hydrogel concentrations of 2 and 4 g L-1 may increase the quality of Eucalyptus dunnii seedlings and reduce their nursery time