Seed dormancy is a phenomenon observed in several tropical species. This condition causes low and non-uniform germination. The present study was designed to identify an efficient method of breaking seed dormancy in Stryphnodendron pulcherrimum. Seeds of four mother plants were subjected to the following treatments: immersion in sulfuric acid for 2, 4, 6, 8, 10 and 12 min and scarification on 150-grit sandpaper. Seeds were sown on substrate containing sand and sawdust (1:1). It was evaluate the days to onset seedlings emergence, seedlings emergence (SE), emergence speed index (ESI), germination (G), hard seeds (HS), dead seeds (DS), dormant seeds (DMS), abnormal seedlings (AS) and dry mass of aerial part (DMAP) and roots (DMR). The experimental design was completely randomized with four replications of 25 seeds for each treatment. Data were subjected to analysis of variance and means compared by Tukey's test (p < 0.05). Significant differences among treatments were observed for ESI, SE, G, HS, DMAP and DMR. Highest HS was observed in control treatment (85%). Highest G was observed in seeds scarified with sulfuric acid for 10 min (82%) and 12 min (74%). These treatments also showed highest ESI, DMAP and DMR, indicating that these scarification treatments were the most efficient in overcoming dormancy.
RESUMO:A demanda por sementes florestais nativas vem crescendo, devido a produção de mudas que visam recuperar áreas abandonadas, degradadas e de reflorestamento, tornando-se imprescindível conhecer o comportamento dessas sementes quanto a tolerância à dessecação e armazenamento, visando sua conservação. O objetivo do trabalho foi classificar as sementes de Manilkara huberi quanto à tolerância à dessecação e ao comportamento no armazenamento. Após o beneficiamento das sementes, foram determinados os teores de água das sementes recém-beneficiadas e submetidas ao processo de secagem, seguidos pelos testes de germinação. De acordo com os resultados, conclui-se que as sementes de M. huberi são classificadas como recalcitrantes, por não tolerarem o processo de secagem e o armazenamento em baixas temperaturas. A espécie M. huberi pertence ao grupo de espécies clímax. ABSTRACT:The demand for native forest seeds has been increasing due to the production of seedlings, used in the recovery of abandoned and degraded areas, as well as reforestation zones. To properly conserve these seeds, however, one needs to understand their tolerance to desiccation and storage. Thus, the objective of this work was to classify Manilkara huberi seeds regarding desiccation tolerance and storage behavior. After processing and water content determination of the newly harvested seeds, they were submitted to the drying process, followed by germination tests. According to the results, it is concluded that the seeds of M. huberi are classified as recalcitrant because they do not tolerate the drying process and the storage at low temperatures. The species M. huberi belongs to the group of climax species.Recebido em: 13/09/2018 Aceito em: 12/01/2019 1 Classificação fisiológica de sementes de maçaranduba quanto a tolerância à dessecação e ao armazenamento Physiological classification of maçaranduba seeds: tolerance to desiccation and storage
The objectives of this work were to characterize fruits and seeds and evaluate seed germination and seedling vigor from fifteen parent plants of Parkia gigantocarpa Ducke. The fresh weight, length, width, and thickness of fruits and seeds were determined. The germination was tested in a sand substrate, with four replications of 25 seeds per treatment (parent plants). The number of days for emergence, emergence percentage, emergence speed index, germination percentage, and seedling dry weight were evaluated. The fruits presented means for fresh weight, length, width, and thickness of 115.0 g; 621.3 mm; 60.8 mm, and 9.8 mm, respectively. The seeds presented means for fresh weight, length, width, and thickness of 1.1 g, 22.8 mm, 11.2 mm, and 7.0 mm, respectively. The emergence was fast and uniform, which occurred from the fifth to the sixth day after seeding, reaching 91% germination for the parent HB9, but not differing from the parents HB2, HB3, and HB6. The seedlings from the parents HB2, HB3, HB6, and HB9 were more vigorous due to their higher dry matter accumulation. The results found showed that, even belonging to the same species, P. gigantocarpa seeds from different parent plants present variability in biometric characteristics of fruits and seeds. The seed collected from different parent plants showed differences in germination capacity and seedling vigor.
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