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

Marcio Carlos Navroski,Mariane De Oliveira Pereira,Maristela Machado Araujo,Lia Rejane Silveira Reiniger,Claudimar Sidnei Fior,Gilmar Schafer

doi:10.1590/0100-67622016000400006

Abstract

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.

Highlights

For meeting the constantly expanding demand for forest products it is necessary to establish new plantations, which, in order to be profitable, must have a high productivity rate and allow a relatively short cutting cycle associated with the products’ quality and sustainability
The seedlings height (H), neck diameter (D), shoot dry matter (SDM), root dry matter (RDM), total dry matter (TDM), height/neck diameter ratio (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
The opposite behavior was observed for the aeration space (AS), which has lowered as the concentration of hydrogel added to the substrate increased (Figure 1B)

Summary

Introduction

For meeting the constantly expanding demand for forest products it is necessary to establish new plantations, which, in order to be profitable, must have a high productivity rate and allow a relatively short cutting cycle associated with the products’ quality and sustainability. When considering the installation of forest stands, the quality of the seedling should be prioritized as it has direct impact on the productivity as well as on the quality of the final product (CALDEIRA et al, 2007). In addition to the substrate, fertilizing and watering are considered to be the main factors related to forest seedlings production costs. Water-retaining polymers have been marketed under the excuse that, when incorporated into the substrate, they allow a higher retention of water and fertilizers, which can be slowly released to plants due to absorption-release cycles. Their high cation exchange capacity (CEC) reduces the leaching of nutrients (TAYLOR; HALFACRE, 1986)

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Conclusion