Glauciana da Mata Ataíde

Alterations in seed reserves of Dalbergia nigra ((Vell.) Fr All. ex Benth.) during hydration

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.

Germinação de sementes de Melanoxylon brauna schott em diferentes temperaturas

The objective of this study was to investigate the effect of temperature on the germination of Melanoxylonbrauna seeds and identify cardinal temperatures for germination, as well as to evaluate the efficiency of the electrical conductivity test to determine the cardinal temperatures. Therefore, three testswere performed. In the first test, the determination of imbibition curves was performed at each temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45oC), the seeds were weighed every two hours for a period of 12 hours and after every 12 hours until the root protrusion of 50% of the seeds, or 120 hours when there was no germination. In the second test, to identify the cardinal temperatures, seeds were kept under each temperature for a period of 10 days in DBO under constant light. In the third test, an electrical conductivity test was performed with the seeds incubated for 24, 48 and 72 hours of imbibition in each of the temperatures, and then were placed inerlenmeyer flasks with 75 mL of deionized water at 25oC for 24 hours for subsequent reading of the electrical conductivity. It is more judicious to recommend temperature ranges for germination than punctual temperatures. The cardinal temperatures (theoretical) for the characteristic germination rates are: 12.3oC - minimum - 30.0oC optimal (theoretical) and 42.7oC maximun. The temperature ranges considering all the variables investigated were: 12.1 to 12.6oC (minimum); 30.0-35.8oC (optimum) and 42.4-43.0oC (maximum). The specie has a wide range of germination with respect to temperature, and germination was observed in the temperature range from 12.0 to 42.0oC. The electrical conductivity test was efficient to evaluate the effect of temperature onseeds and according to this test the optimal temperature is 27.0oC.

ALTERAÇÕES FISIOLÓGICAS E BIOMÉTRICAS EM SEMENTES DE Melanoxylon brauna Schott DURANTE A GERMINAÇÃO EM DIFERENTES TEMPERATURAS

Objetivou-se neste trabalho estudar as alteracoes biometricas e a germinacao das sementes de Melanoxylon brauna em diferentes temperaturas. As sementes foram colocadas para germinar nas temperaturas constantes de 10, 25, 30 e 40 °C. Sementes da especie tambem foram expostas as temperaturas de 10 e 40 oC, por periodos de 24, 48, 72 e 96 h, e transferidas para a temperatura de 25 oC. Foram analisados a porcentagem de germinacao, o indice de velocidade de germinacao (IVG) e o tempo medio de germinacao. Durante a germinacao nas temperaturas constantes, avaliaram-se as alteracoes biometricas do comprimento e a massa de materia fresca dos eixos embrionarios. Nas temperaturas de 25 e 30 oC, foram verificados 93 e 98% de germinacao, respectivamente. Em 10 e 40 oC, a germinacao foi de 5%. O IVG foi significativamente maior a 30 oC. A embebicao das sementes a 10 e 40 oC, com posterior retorno a 25 oC, resultou em acrescimos na germinacao, em comparacao com as temperaturas constantes. O comprimento e a massa de materia fresca dos eixos embrionarios aumentaram continua e progressivamente durante a embebicao.

Atividades de α-galactosidase e poligalacturonase durante a hidratação de sementes de Dalbergia nigra ((Vell.) Fr. All. ex Benth.) sob diferentes temperaturas

Germination is a process that begins with seed water uptake, stimulating enzyme synthesis or activating enzymes already present. The objective of this study was to evaluate variations in monosaccharide reserves and the activities of the α-galactosidase and polygalacturonase enzymes during the hydration of two lots of Dalbergia nigra (Bahia Rosewood) seeds. Seeds from different origins constituted the two lots I and II, classified as high and low vigor, respectively. Both lots were placed in desiccators with a high relative humidity to hydrate and at 15 and 25 °C until levels of 10, 15, 20 and 25% moisture levels in seeds were reached. The seed cotyledons were analyzed for the quantity of monosaccharides and enzyme activity. The control had higher concentrations of xylose and rhamnose, which decreased during hydration until the 15% level was reached, after which concentrations increased again in both lots. Lot I, with a superior quality, showed higher glucose synthesis and degradation during seed hydration. Both enzymes were pre-existing since activity was already present in the seeds without imbibition. The polygalacturonase enzyme increased and the α-galactosidase enzyme remained relatively constant during seed hydration.

Volume de substrato e idade: influência no desempenho de mudas clonais de eucalipto após replantio

Rapid early growth of tree seedlings is critical for the forest plantation success. This study aimed to evaluate the influence of age and substrate volume on the clonal eucalypt seedlings performance after replanting. The experiment was conducted in randomized blocks with ten replications in a 2 x 4 factorial arrangement (clonal seedlings grown in tubes of 53 and 180 cm³ and four ages - 60, 75, 90 and 120 days) in a 3 x 3,33 m spacing. As an additional treatment, it was evaluated plants of a commercial plantation, settled 20 days before the experiment. Seedling replanting with higher substrate volume provided better initial growth in the field. However, at 12 months of age, replanting seedling growth was not influenced by age or by the amount of substrate used for seedling production.

INTERAÇÃO ÁRVORES E VENTOS: ASPECTOS ECOFISIOLÓGICOS E SILVICULTURAIS

In many parts of the world, significant damage to forests are seen due to the action of strong winds, as they occur on tops of trees and can irreparably damage whole forest settlements, breaking or uprooting trees. It has been a constant concern to both understand the phenomenon as the tolerance of genotypes grown in different environments subject to performance of these meteorological phenomena. Thus, this work was carried out as a bibliographic research on the effect of wind on forests, addressing ecophysiological and silvicultural aspects. The knowledge of anatomical, physical and mechanical properties of wood, as well as the environmental factors, allows a better understanding of the problem in order to facilitate the proposal of measures to minimize damages.

VEGETATIVE PROPAGATION OF Schizolobium amazonicum BY CUTTING

O objetivo do presente trabalho foi desenvolver uma metodologia para a propagacao vegetativa do parica (Schizolobium amazonicum) via estaquia, avaliando o efeito do AIB (0, 8000, 16000 e 32.000 mg.L-1) no enraizamento de estacas apicais e intermediarias. As bases das estacas foram imersas na solucao de AIB por 10 segundos e em seguida foram estaqueadas em tubetes de polietileno de 110 cm³, preenchidos com substrato orgânico (Bioplant(r)). A irrigacao das mudas foi feita por meio de um sistema de nebulizacao com uma vazao unitaria de 7 L.h-1. Apos 40 dias, avaliou-se: porcentagem de sobrevivencia, porcentagem de estacas enraizadas, porcentagem de raizes observadas na extremidade inferior do tubete, numero medio de raizes, comprimento da maior raiz, presenca de calos, vigor e massa seca de raizes. Os resultados para as caracteristicas avaliadas, com destaque para a sobrevivencia, demonstraram que as maiores medias foram obtidas em estacas intermediarias, independente da dose de AIB utilizada. A maior porcentagem de enraizamento, numero de raizes, comprimento e massa seca das raizes, em ambos os tipos de estacas foi obtido com a maior dose de AIB testada (32.000 mg.L-1). Com base nos resultados obtidos, conclui-se que a tecnica de estaquia associada a aplicacao de reguladores vegetais pode ser utilizada para a propagacao vegetativa de S. amazonicum.

SUPERAÇÃO DA DORMÊNCIA DAS SEMENTES DE Delonix regia (Bojer ex Hook.) Raf.

RESUMO – Delonix regia (flamboyant) e uma especie arborea amplamente utilizada no Brasil, de alto valor ornamental. Sua propagacao ocorre por meio de sementes, que apresentam dormencia pela impermeabilidade do tegumento a agua. Com o objetivo de determinar a melhor metodologia para a superacao da dormencia, as sementes da especie foram submetidas a diferentes tratamentos: 1) imersao em agua fervente por 1 min; 2) imersao em agua a 80 °C e a 90 °C por 1 e 3 min; 3) escarificacao manual com lixa; e 4) imersao em acido sulfurico concentrado por 15, 30, 45 e 60 min, alem da testemunha. Apos cada tratamento, as sementes foram colocadas para germinar em rolo de papel, na temperatura de 25 oC. Em uma segunda etapa, os tratamentos mais efetivos na quebra de dormencia das sementes foram aplicados e a germinacao, testada a temperatura de 30 °C. Em ambas as temperaturas, as contagens de germinacao (plântulas normais) foram realizadas diariamente. O tratamento das sementes de flamboyant em agua quente a 90 oC por 1 min foi o mais eficiente na promocao da germinacao, sendo pratico e dispensando o uso de tratamentos quimicos. O teste de germinacao realizado a temperatura de 30 °C nao forneceu resultados satisfatorios, com menores porcentagens de plântulas normais e IVG que os testes a 25 oC. Foram descritas como plântulas normais as que possuiam visiveis dois cotiledones semiabertos, hipocotilo alongado, raiz primaria bem desenvolvida e raizes adventicias curtas. Conclui-se que sementes de Delonix regia germinam melhor a 25 oC apos a imersao por 1 min em agua a 90 oC, sendo este indicado como tratamento para superacao da dormencia da especie. Palavras-chave: Flamboyant; Germinacao; Temperatura. OVERCOMING SEED DORMANCY OF Delonix regia (Bojer ex Hook.) Raf.

Cobertura retrátil no crescimento de mudas clonais de eucalipto

O sucesso na implantacao de povoamentos florestais depende, em grande parte, do desempenho das mudas em resposta as variacoes no ambiente do viveiro. Objetivou-se, neste trabalho, avaliar o crescimento e a qualidade de mudas clonais de eucalipto em resposta a utilizacao de cobertura retratil nos canteiros de crescimento. O experimento foi conduzido no periodo de abril a julho de 2008, constituindo-se de um delineamento inteiramente casualizado em esquema fatorial 2 x 6, em dois ambientes (com cobertura retratil e sem cobertura retratil) e seis diferentes materiais geneticos. Foram avaliadas as caracteristicas altura da parte aerea, diâmetro do colo e pesos de materia seca de raizes, parte aerea e total das mudas. Os resultados indicaram que a utilizacao de cobertura retratil influenciou positivamente no crescimento de mudas clonais de eucalipto, as quais exibiram maiores medias de altura e incremento em biomassa de raizes e total para a maioria dos clones testados, o que contribuiu para o desenvolvimento das plantas, que apresentaram qualidade satisfatoria aos 55 dias.