Alterações nas reservas de sementes de Dalbergia nigra ((Vell.) Fr. All. ex Benth.) durante a hidratação

Seed imbibitions is the first stage of the germination process and is characterized by the hydration of tissues and cells and the activation and/or induction of the enzymes responsible for mobilizing reserves for respiration and the construction of new cell structures. The objective of this study was to investigate the alterations in reserve substances during slow hydration of Bahia Rosewood (Dalbergia nigra) seeds in water. Seeds from two different lots (Lot I and II) were placed in saturated desiccators (95-99% RH) to hydrate at 15 and 25 °C until water contents of 10, 15, 20 and 25% were reached. At each level of hydration, changes in lipid reserves, soluble carbohydrates, starch and soluble proteins were evaluated. The mobilization of reserves was similarly assessed in both lots, with no differences being observed between the two hydration temperatures. Lipid contents showed little variation during hydration, while the contents of soluble carbohydrates and starch decreased after the 15% water content level. Soluble proteins showed a gradual tendency to decrease between the control (dry seeds) up to 25% water content

Luz, substrato e temperatura na germinação de sementes de cedro-vermelho Light, substrate and temperature in the germination of seeds of Cedrela odorata

O objetivo deste estudo foi avaliar o tipo de substrato, a temperatura e os regimes de luz mais adequados à germinação de sementes de Cedrela odorata L. O delineamento experimental adotado, em todos os ensaios, foi o inteiramente casualizado com quatro repetições de 25 sementes cada. As temperaturas constantes de 25 e 30ºC, a temperatura alternada de 20-30ºC e os substratos pó de coco e areia são as melhores condições para a germinação das sementes de C. odorata. A germinação das sementes da espécie estudada não se mostrou sensível aos diferentes regimes de luz aplicados.<br>This work aimed to evaluate the kind of substrate, and temperature and light conditions more suitable for seed germination of Cedrela odorata L. The experimental design adopted in all experiments was the completely randomized design with four repetitions of twenty-five seeds each. The constant temperatures (25 and 30ºC), the alternated temperature (20-30ºC), and the coconut fiber and sand substrates are the better conditions for seed germination of C. odorata. Seed germination of the studied specie showed no sensitiveness to the different levels of light applied

Substrato, temperatura de germinação e desenvolvimento pós-seminal de sementes de Dalbergia nigra Germination substrate, temperature and post-seminal development of Dalbergia nigra seeds

O objetivo deste trabalho foi definir o tipo de substrato e a temperatura mais adequada à germinação de sementes de Dalbergia nigra (Vell.) Fr. All. Ex Benth (jacarandá-da-bahia), e conhecer a morfologia de seu desenvolvimento pós-seminal e caracterizar as plântulas normais, o tipo de germinação e os padrões de anormalidade. As sementes foram semeadas nos substratos sobre papel, rolo de papel e sobre vermiculita, nas temperaturas constantes de 20, 25, 30 e 35&deg;C e alternadas de 20-30&deg;C e 20-35&deg;C. O delineamento estatístico empregado foi o inteiramente casualizado (6x3), com quatro repetições de 50 sementes. Foram analisados os seguintes parâmetros: porcentagem de germinação normal (plântulas normais) e velocidade de emergência de plântulas. Os melhores resultados foram verificados nas temperaturas de 25&deg;C e 20-30&deg;C, nos substratos sobre vermiculita e rolo de papel. Plântulas normais foram caracterizadas como faneroepígeas em relação ao tipo de germinação.<br>The objective of this work was to define the germination substrate of Dalbergia nigra (Vell.) Fr. All. Ex Benth (jacarandá-da-bahia), to evaluate the most appropriate temperature for its seeds germination, and to study its post-seminal morphology, showing normal and abnormal seedlings patterns. Seeds were sowed on filter paper, towel paper and vermiculite, using the constant temperatures of 20, 25, 30 and 35&deg;C as well as alternate temperatures of 20-30&deg;C and 20-35&deg;C. The statistical design was completely randomized (6x3) with 50 seeds sowed in four replications in which the following parameters were analyzed: normal germination (normal seedlings) percentage and speed emergence index. The best results were obtained for temperatures of 25&deg;C and 20-30&deg;C in vermiculite and towel paper substrates. Normal seedlings were classified as faneroepigeal germination type