Abstract
The Caesalpinia echinata Lam. species, belongs to the Fabaceae family, popularly known as Pau Brazil, is a large tree, native to Brazil, that can be found from Ceará to Rio de Janeiro, with a relevant national historic and economic value. The objective of this study was to evaluate the effects of water stress at different temperatures on germination and seed vigor. The experiment was carried out at the Laboratório de Análise de Sementes of the Centro de Ciências Agrárias of the Universidade Federal da Paraíba, Areia-Paraíba. The water stress was formulated with solutions of polyethylene glycol 6000 (PEG 6000) in different osmotic potentials of 0.0 (control), -0.2; -0.4; -0.6 MPa at constant temperatures of 25, 30 and 35 °C, in a completely randomized design. The percentage of germination, first counting of germination, germination speed index, length and dry matter of seedlings were evaluated to determine the effects of the treatments. Decreases of the osmotic potential negatively influenced the germination and vigor of C. echinata seeds at the three evaluated temperatures (25 ºC, 30 ºC, 35 °C).
Highlights
The Caesalpinia echinata Lam. species belongs to the Fabaceae family, popularly known as Pau Brazil, pau-rosado or pau-de-pernanbuco, is native to Brazil and can be found from Ceará to Rio de Janeiro in the Atlantic Rainforest (Lorenzi, 2016; Rocha & Barbedo, 2008)
The test was performed on germinators Biological Oxygen Demand (BOD) type at constant temperatures of 25, 30 and 35 °C with photoperiod of 8/16 hours of light and dark, respectively, using fluorescent lamps day-light type (4 × 20 W), using 100 seeds divided into four replicates of 25, treated with the fungicide Captan® in the dose of 240 g for 100 kg of seeds
At the temperature of 25 °C, the maximum germination (93%) was obtained in the osmotic potential of 0.0, with a decrease following the more negative water potentials. At this temperature, seed germination was higher in all osmotic potentials when compared to temperatures of 30 and 35 °C
Summary
The Caesalpinia echinata Lam. species belongs to the Fabaceae family, popularly known as Pau Brazil, pau-rosado or pau-de-pernanbuco, is native to Brazil and can be found from Ceará to Rio de Janeiro in the Atlantic Rainforest (Lorenzi, 2016; Rocha & Barbedo, 2008). C. echinata is currently on the list of endangered species due to centuries of exploitation. The wood of this species is very resistant and heavy and was extensively explored for civil and naval construction, and for production of musical instruments. Knowledge of ideal conditions for seed germination of each species is essential, since factors such as temperature, light, and salinity can affect the germination process. The main factor that influences the germination is the water, which must be in adequate quantity, because when in excess or scarcity, can result in negative effects on the germination (Brasil, 2009; Carvalho & Nakagawa, 2012)
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