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The seeds of several species of the Leguminosae family have a type of dormancy that makes sexual propagation difficult. The seeds of Deguelia spruceana (Benth.) A.M.G. Azevedo & R.A. Camargo, also known as timbó-pau in Brazil, may be highlighted. Viable methods to accelerate the germinative process of seeds of native species are required to be used in the process of the reposition of native vegetation and the recovery of degraded areas. The most analyzed seeds are those of agricultural interest, placing secondary the native species, such as D. spruceana. Current research evaluates six methods for overcoming dormancy in seeds of D. spruceana. Treatments included file, alcohol and acid in different conditions and at different times. After scarification, seeds were conditioned to germinate in plastic recipients with washed sand as substrate and deposited in agricultural greenhouse. Percentage of seed germination, index of germination speed, stalk diameter, root length, plant height and fresh and dry mass of plant were evaluated. There was a significant effect of treatments applied for all variables, except for the stalk's diameter. Regardless of method, emergency percentage was less than 22%. For sexual propagation of species D. spruceana, dormancy may be overcome by chemical scarification by immersion in sulphuric acid for 5 minutes. [ABSTRACT FROM AUTHOR]

In the Anonaceae family, the seeds present a rudimentary embryo, of slow development which inhibits or slows germination. The objective of this study was to evaluate the efficiency of different methods of overcoming seed dormancy Annona cf. montana, in order to accelerate and standardize germination. They were two experiments, with chemical and physical treatments. The experimental design was a completely randomized design, with 5 replicates, 20 seeds each. The germination evaluation was performed at 30 °C for 40 days. At the end, the percentage of germination, average germination time, average germination speed, speed index and germination uniformity coefficient were evaluated. With the results obtained, it was observed that the percentage of germination was improved in 0.1 and 0.2% of KNO3, in 0.2 and 0.5% of GA3 or with osmoconditioning in polyethylene glycol for 8 days. [ABSTRACT FROM AUTHOR]

Dormancy is characterized as the inability of seed germination even under favorable conditions. It is an evolution strategy in several species. Warm-bath treatments were tested at different times with Flamboyant seeds and treatments with sulfuric acid at different times in white capulin seeds were tested so that the break of dormancy of species Flamboyant (Delonix regia) and white capulin (Trema micrantha) could be investigated. After treatment, seeds were placed in a gerbox and taken to a BOD-type refrigerated buffer at 25°C and 12-h photoperiod. Experiment was evaluated every eight days. Best results for the flamboyant were reported for permanence time between 10 and 20 min in the warm bath. In the case of the white capulin, best results occurred at 40-min exposure time in sulfuric acid. The two techniques for the overcoming of dormancy proved to be efficient and complemented data in the literature, and revealed more efficient strategies for germination, overcoming of dormancy and management of the species under analysis. [ABSTRACT FROM AUTHOR]

O objetivo foi avaliar o efeito de diferentes concentrações de ácido sulfúrico na desinfestação, oxidação e germinação in vitro de sementes de Pterogyne nitens. O experimento foi conduzido no laboratório de Cultura de Tecidos Vegetais do IFMG. O delineamento foi inteiramente ao acaso, com quatro repetições de 12 sementes, sendo estudado o efeito de cinco concentrações de ácido sulfúrico. A avaliação do número de sementes germinadas, oxidadas e desinfestadas foi feita três vezes por semana, por 20 dias. Os dados foram submetidos à análise de variância. As maiores porcentagens de desinfestação 27,08 e 16,67% foi observado nas sementes tratadas com 25 e 100% do ácido. Os tratamentos com 75 e 100% de ácido sulfúrico não se diferenciaram e apresentaram maiores porcentagens de germinação (93,75 e 83,33%, respectivamente) e oxidação (89,58 e 83,33 %, respectivamente). A concentração de 100% de ácido sulfúrico apresentou os melhores resultados para a desinfestação e germinação.

Senna silvestris é um vegetal de hábito arbóreo nativo do Brasil, com potencial para arborização urbana, cujas sementes são dormentes. Considerando a necessidade de melhor conhecimento das espécies florestais nativas, e mais especificamente dos processos de superação de dormência, este estudo teve por objetivo verificar o comportamento de sementes de Senna silvestris submetidas a diferentes tempos de exposição (0, 0,5, 3,0 e 5,0 minutos) ao ácido sulfúrico concentrado (98%) com quatro repetições de 25 sementes em delineamento inteiramente casualizado. As variáveis avaliadas foram porcentagem, tempo médio, índice de velocidade e velocidade média de emergência das plântulas. Foi realizada análise de variância, comparação entre médias e correlação. A imersão das sementes em ácido sulfúrico entre 0,5 e 5 minutos proporcionou os maiores valores de emergência, sendo estatisticamente iguais entre si e diferentes da testemunha (0 minuto). Houve correlação positiva moderada entre porcentagem e índice de velocidade de emergência com os diferentes tempos de exposição das sementes ao ácido. Recomenda-se a escarificação química com ácido sulfúrico entre 0,5 e 5 minutos para a superação de dormência de sementes de Senna silvestris.

The objective of this study was to evaluate different treatments used for Hymenaea courbaril seed dormancy overcoming. The research was carried out in a laboratory at the College of Agronomy "Dr Francisco Maeda", in Ituverava, SP, Brazil, where they were tested the pre-germination treatments: seeds immersion in sulfuric acid (H2SO4) for twenty minutes, mechanical scarification seeds using sandpaper; exposition of seeds the Atta ssp. and intact seeds (control). The experimental design was completely randomized. We evaluated the moisture content, biometric aspects of the seeds (length and width); percentage of germination, the germination speed index and seedling dry mass. The moisture content, length and width of seeds were 4,9%, 22,6 mm and 14,6 mm, respectively. Based on the results obtained and the conditions that the experiment was conducted, it is recommended H. courbaril seeds immersion in sulfuric acid (H2SO4) for twenty minutes to dormancy overcoming of them and mechanical scarification seeds how second option. [ABSTRACT FROM AUTHOR]

O Zizyphus joazeiro Mart. apresenta redução sensível no número de indivíduos em seu ambiente natural devido, entre outras causas, à ocorrência de dormência exógena da unidade de dispersão (impermeabilidade à água). Avaliou-se o efeito do período de imersão (0, 30, 60, 90, 120 e 150 min) dessas unidades de dispersão, em ácido sulfúrico (98 %), na emergência e vigor das sementes (primeira contagem, índice de velocidade e tempo médio de emergência, altura e massa seca de plantas). O experimento foi realizado em casa de vegetação, utilizando-se o delineamento inteiramente ao acaso, com seis tratamentos e quatro repetições. O pré-condicionamento das unidades de dispersão de Zizyphus joazeiro Mart., em ácido sulfúrico concentrado, mostrou-se eficiente na superação da dormência dessa espécie, promovendo aumento na porcentagem e velocidade de emergência, primeira contagem de emergência, na altura e massa seca de plantas e redução no tempo médio para emergência. A eficiência do tratamento químico com ácido sulfúrico concentrado depende do período de imersão, sendo a faixa entre 74 e 115 min mais adequada para proporcionar maiores porcentagens de emergência e de vigor.Zizyphus joazeiro Mart. trees have been declining in number in their natural habitat due to, among other reasons, the occurrence of dormancy of dispersal units (water impermeability). The effect of the immersion time (0, 30, 60, 90, 120 and 150 minutes) of Zizyphus joazeiro Mart. dispersal units in concentrated sulfuric acid (95-98 %) was evaluated through the emergency and vigor (first count, speed index and mean emergence time, plant height and dry matter weight). The experiment was performed under greenhouse conditions, with a completely randomized experimental design, six treatments and four replications. The pre-conditioning of Zizyphus joazeiro Mart. dispersal units with immersion in concentrated sulfuric acid was efficient for breaking the seed dormancy and also for increasing the emergence percentage and speed, the emergence first count, plant height and dry matter weight and reduction in the mean emergence time. The efficiency of this chemical treatment, with concentrated sulfuric acid, was shown to be dependent on the immersion time, being the most suitable to provide larger emergency percentages and vigor between 74 and 115 minutes.

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Seed dormancy limits the seedling production and potential of use in Adenanthera pavonina L. The objective of this research was to evaluate the best dormancy breaking method in Adenanthera pavonina L. seeds. It was carried out at the Ceulji/Ulbra Laboratory of Botany, from April to June 2007, and six dormancy breaking treatments (T) were tested: T1 - Boil for 15 minutes and rest for 16 hours, in the same water; T2 - Boil for 10 minutes and rest for 16 hours, in the same water; T3 - Immersion in boiling water (95ºC) and rest for 24 hours, in the same water; T4 and T5 - Immersion in concentrated sulfuric acid (98%), for 5 and 10 minutes, respectively; and T6 - Control. The following items were evaluated: days until germination, germination speed index (GSI), and germination percentage (%GER). Variance analysis was used to evaluate the data and means were compared by using the Duncan’s test (5%). Treatments 1 and 2 caused seeds damage, preventing their germination. Treatments 4 and 5 showed no significant differences, but were more favorable to dormancy breaking, if compared to the other treatments. KEY-WORDS: Germination; chemical scarification; boiling; sulfuric acid. A dormência das sementes limita a produção de mudas e o potencial de uso de Adenanthera pavonina L. O presente trabalho objetivou determinar o melhor método para quebra de dormência, em sementes de A. pavonina. O experimento foi conduzido no Centro Universitário Luterano de Ji-Paraná (Ceulji/Ulbra), de abril a junho de 2007. Foram testados seis tratamentos (T): T1 - Fervura por 15 minutos e repouso por 16 horas, na mesma água; T2 - Fervura por 10 minutos e repouso por 16 horas, na mesma água; T3 - Imersão em água quente (95ºC) e repouso por 24 horas, na mesma água; T4 e T5 - Ácido sulfúrico concentrado (98%), durante 5 e 10 minutos, respectivamente; e T6 - Testemunha. Avaliou-se o índice de velocidade de germinação (IVG), percentagem de germinação (%G) e massa de matéria seca de plântulas. Os dados foram submetidos a análise de variância, sendo as médias comparadas pelo teste de Duncan, a 5% de significância. Sementes submetidas a fervura, por 10 e 5 minutos, foram deterioradas, o que impediu a germinação. A imersão das sementes em ácido sulfúrico, por 5 e 10 minutos, foi mais favorável à superação da dormência, em relação aos demais tratamentos. PALAVRAS-CHAVE: Germinação; escarificação química; fervura; ácido sulfúrico.