Abstract
Acacia is an important forest species of rapid growth whose seeds have tegument dormancy. In this work it was intended to characterize water absorption pattern after seed dormancy break, and to determine the amount of water, container size and the need of breaking the tegument dormancy, as to perform electrical conductivity test in small and large seeds of Acacia mangium (Fabaceae). The seeds were collected from 10, 8 and 6 years old trees established in poor yielding-capacity soils on savannah areas of Roraima, Brazil; seeds were classified in six lots concerning to seed size and tree age. Germination tests (50 seeds and four replications per lot) were carried out on germitest® paper maintained on gerbox at 25 °C. Imbibition was verified by seed weighing at different times (0, 2, 5, 8, 12, 16, 24, 36, 48, 60, 72, 84, 96 and 120 hours). The electrical conductivity test consisted of three experiments, distinguished by the amount of water used and by the container size in which seeds were immersed. Seeds of A. mangium coming from 10 years old trees presented increased germination percent and germination speed than seeds of six-year old trees. Small seeds presented increased in electrical conductivity and water absorption until 120 hours when compared to large seeds. The immersion of seeds of A. mangium in 40 mL of distilled water into 180 mL plastic containers, after dormancy break, it is indicated for the determination of electrical conductivity test. The ratio of electrolytes by seed mass, after 24 hours of immersion in water, turns electrical conductivity test more accurate concerning A. mangium seeds.
Highlights
In the latest decades, the forest-covered area of the terrestrial globe has been devastated in consequence of the irrational logging (Rodrigues, Kohl, Pedrinho, Arias, & Favero, 2008)
Some authors have pointed out the importance of the development/or adjustment of these fast tests for the different forest species, since the efficiency of procedures in the evaluation of physiological potential will depend on them (Lopes, Silva, & Vieira, 2013; Araldi & Coelho, 2015). This way, the objective of this research was to evaluate the potential use of the best water absorption pattern, container size and the need of breaking the tegument dormancy, for the application of the electrical conductivity test in small and large seeds of Acacia mangium, coming from commercial plantings of different ages, established in low yielding capacity soils on savannah areas of Roraima
The average results concerning 1 000 seed mass obtained for the six lots are shown in table 1, where the average mass of small seeds was 7.54 g, for large seeds 9.37 g, while the lot of seeds coming from trees six years old presented less mass (7.96 g)
Summary
The forest-covered area of the terrestrial globe has been devastated in consequence of the irrational logging (Rodrigues, Kohl, Pedrinho, Arias, & Favero, 2008). In the electrical conductivity test, which allows vigor comparisons between different samples of seeds, the values obtained are due to the disorganization of cell membrane and the decrease of the respiratory and biosynthetic capacity (Coutinho, Silva-Mann, Vieira, Machado, & Machado, 2007). Due to those two processes, electrolytes are released in imbibition water, the intensity of the electric current of those electrolytes being measured even by total or individual method (Vieira & Krzyzanowski, 1999)
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