Optimal temperature for seed germination of brazilian tree species

O objetivo neste trabalho foi avaliar os aspectos ecológicos e aplicados da temperatura na germinação de sementes de espécies arbóreas brasileiras. Foram analisadas informações, obtidas por meio de dados secundários, sobre o efeito da temperatura na germinação de 272 espécies arbóreas nativas e estabelecidas as relações da temperatura ótima com o bioma de ocorrência e com o grupo sucessional da espécie. As temperaturas de 25 °C e 30 °C foram as mais favoráveis para a germinação, havendo relação entre a temperatura ótima e o bioma de ocorrência da espécie, mas não entre essa temperatura e o grupo sucessional. Com base nos resultados, é possível indicar que o teste de germinação com sementes de espécies arbóreas brasileiras seja conduzido mediante o uso de temperatura constante de 25 °C para as espécies dos biomas Cerrado e Mata Atlântica e de 30 °C para as espécies do bioma Amazônia, salvo nos casos de espécies para as quais há requerimentos específicos de temperaturas alternadas para a superação da dormência das sementes.The objective of this study was to evaluate the ecological and applied aspects of temperature for seed germination of Brazilian tree species. The information obtained from secondary data for temperature effects on the seed germination of 272 Brazilian tree species was analyzed and the relationships between optimal temperature and the biome where the species occur and the species succession group were developed. Temperatures of 25 °C and 30 °C were the most favorable for seed germination and the optimal germination temperature was related to the biome where the species occur but not to its succession group. Based on these results, a temperature of 25 °C may be recommended for germination tests of Brazilian tree species which grow in the Cerrado and Atlantic Forest biomes, and 30 °C for those species from the Amazon biome, except for species which have specific requirements of alternating temperatures for overcoming seed dormancy

Chemical scarification to overcome dormancy on Colubrina glandulosa Perk. (Rhamnaceae) seeds

Este trabalho objetivou avaliar diferentes períodos de imersão de sementes de saguaraji-vermelho (Colubrina glandulosa) em ácido sulfúrico, para a superação da dormência. O experimento foi dividido em duas etapas. Na primeira, sementes de cinco lotes provenientes de diferentes localidades (dois recém-coletados e os demais armazenados por um, dois e três anos) foram escarificadas quimicamente com ácido sulfúrico concentrado por 30, 60, 90, 120 e 150 min. Na segunda etapa, as sementes dos lotes recém-coletados foram imersas em ácido por 20, 30, 40, 50 e 60 min. As sementes escarificadas com ácido e as não escarificadas foram avaliadas diariamente quanto à germinação (rolo de papel, 25 ºC, no escuro e quatro repetições de 25 sementes por tratamento) - com os dados, foram calculadas sua porcentagem e velocidade. Na primeira fase, as médias dos tratamentos foram comparadas pelo teste de Tukey (P<0,05) e na segunda, por equações de regressão. Os resultados indicaram que a porcentagem de dormência variou entre as sementes dos lotes (taxas mais altas das sementes recém-colhidas), e a escarificação com ácido por 30 a 90 min foi favorável à superação da dormência. Houve prejuízo na germinação com a escarificação das sementes por 120 min e 150 min. Na segunda fase, valores máximos de porcentagem e velocidade de germinação foram obtidos após 60 min de imersão. Diante desses resultados, o armazenamento por um ano e a imersão das sementes em ácido sulfúrico por 30 a 90 min podem ser utilizados, com eficiência, para a superação da dormência de sementes de saguaraji-vermelho.This work aimed to evaluate different immersion periods of Colubrina glandulosa seeds in sulfuric acid for overcoming dormancy. The experiment was divided into two phases. In the first, five seed lots harvested in different localities (two recently harvested and the others in 2004, 2005 and 2006), were chemically scarified in concentrated sulfuric acid for 30, 60, 90, 120 and 150 minutes. In the second phase seeds from recently harvested lots were immersed in acid for 20, 30, 40, 50 and 60 minutes. Germination of scarified in acid and non scarified seeds was evaluated daily (paper roll, 25ºC, darkness and four replicates of 25 seeds per treatment) and, with the data, germination percentage and speed were calculated. In the first phase means were compared by the Tukey test (P<0.05) and in the second the treatments were compared by regressive equations. Results showed that dormancy percentage varied among seed lots (higher intensity for recently harvested seeds) and that scarification in acid for a period between 30 and 90 minutes was favorable for overcoming dormancy. Germination was negatively affected when seeds were scarified for 120 or 150 minutes. In the second phase the maximum values of germination percentage and speed were obtained after immersion for 60 minutes. Based on such results, seed storage for 1 year and immersion in sulfuric acid for a period between 30 and 90 minutes can be efficiently used to overcome C. glandulosa seed dormancy

Desiccation tolerance of cambuci seeds

This work aimed to evaluate the interference of seed desiccation on the occurrence of root protrusion and the formation of normal cambuci seedlings. Seeds were obtained from mature fruits collected from adult plants and submitted to oven drying with forced air circulation at 30±2°C in order to obtain different water contents. The seeds were then submitted to the germination test in a completely randomized design at 25°C and 12 hours photoperiod, and were weekly evaluated for a period of 90 days, regarding the number of seeds with root protrusion, the number of dead seeds and normal seedlings. At the end the germination speed index (GSI) the mean germination time (MGT) and the average speed of germination (ASG) were calculated. Any of these variables were significantly affected until the water content decreased to 14.9%, whereas at 9.1% and 6.6% water contents, there was a significant reduction of root protrusion and GSI, and a higher percentage of dead seeds. Cambuci seeds tolerate desiccation down to 15% water content without losing viability.This work aimed to evaluate the interference of seed desiccation on the occurrence of root protrusion and the formation of normal cambuci seedlings. Seeds were obtained from mature fruits collected from adult plants and submitted to oven drying with forced air circulation at 30±2°C in order to obtain different water contents. The seeds were then submitted to the germination test in a completely randomized design at 25°C and 12 hours photoperiod, and were weekly evaluated for a period of 90 days, regarding the number of seeds with root protrusion, the number of dead seeds and normal seedlings. At the end the germination speed index (GSI) the mean germination time (MGT) and the average speed of germination (ASG) were calculated. Any of these variables were significantly affected until the water content decreased to 14.9%, whereas at 9.1% and 6.6% water contents, there was a significant reduction of root protrusion and GSI, and a higher percentage of dead seeds. Cambuci seeds tolerate desiccation down to 15% water content without losing viability

Estudos de propagação em Smilax fluminensis Steud. (Smilacaceae)

Smilax L. species, popularly known in Brazil as salsaparrilha, have been used in folk medicine as tonic against rheumatism and as anti-syphilitic since the sixteenth century; however, until today, their roots have been explored in an extractive way. The aim of this study was to analyze the propagation of Smilax fluminensis aiming to meet the demand and to propose procedures for its sustainable management. It was analyzed the percentage of seed germination, rooting of aerial and subterranean stem cuttings and plant resprouting capacity after removal of the shoots. The monitoring lasted one year. Seeds were subjected to temperatures: 25&deg;C, 30&deg;C, 20-30&deg;C and 20-35&deg;C under a daily photoperiod of eight hours and in the absence of light. For rooting the stem cuttings, aerial and subterranean stems about 20cm long with two nodal regions were subjected to treatment with distilled water (control) and indolbutyric acid (IBA) at 100ppm. The best germination percentages obtained for S. fluminensis were 80% at 20-30&deg;C under light and 85% at 30&deg;C in the dark. Only subterranean stem cuttings showed significant difference concerning fresh and dry matter of roots with higher values in treatments with hormone compared to the control.As espécies do gênero Smilax L., conhecidas popularmente como salsaparrilha, são empregadas na medicina popular como fortificante contra o reumatismo e antissifilítico desde o século XVI, porém até hoje as suas raízes são exploradas de maneira extrativista. O objetivo deste estudo foi analisar a propagação de Smilax fluminensis visando a auxiliar no atendimento da demanda e apontar propostas para o seu manejo sustentável. Foram analisados a porcentagem de germinação de sementes, o enraizamento de estacas de ramos aéreos e subterrâneos e o acompanhamento ao longo de um ano da capacidade de rebrotamento das plantas após a retirada dos ramos aéreos. As sementes foram submetidas às temperaturas: 25, 30, 20-30 e 20-35&deg;C, sob fotoperíodo diário de oito horas e na ausência de luz. Para o enraizamento de estacas, foram utilizados ramos aéreos e subterrâneos com aproximadamente 20cm com duas regiões nodais submetidas ao tratamento com água destilada (controle) e com ácido indolbutírico (AIB) a 100ppm. As melhores porcentagens de germinação obtidas para S. fluminensis, 80% em 20-30&deg;C no claro e 85% a 30&deg;C no escuro. Apenas as estacas de ramos subterrâneos enraizaram, houve diferença significativa em relação à massa fresca e seca de raízes com valores maiores nos tratamentos com hormônio em relação ao controle

Seed germination of Brazilian Aldama species (Asteraceae)

Brazilian samples from the Aldama genus (Asteraceae) could not propagate vegetatively despite their thickened underground system; thus, this study on sexual propagation is critical given the lack of data on reproductive strategies for such species. The aim for this research was to assess the optimal temperature for Aldama arenaria, A. filifolia, A. linearifolia, A. robustaand A. trichophylla seed germination. Seed germination was evaluated at the constant temperatures 20, 25 and 30 °C and the alternating temperatures 15-35, 20-30 and 20-35 °C with an 8-h daily photoperiod, using fluorescent-lamp. The ungerminated seeds were evaluated for embryo viability. The A. filifolia seed health was also evaluated. The optimal temperatures for germination are 20 and 25 °C for Aldama arenaria, A. filifolia, A. robusta and A. trichophylla seeds and 20 °C for A. linearifoliaseeds. The alternating temperature 15-35 °C is not recommended for germinating seeds from these species. The six fungi taxa studied herein did not affect A. filifolia seed germination