Superação de dormência de sementes de Piptadenia moniliformis Benth
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Data
2010-06-01
Título da Revista
ISSN da Revista
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Editor
Associação Brasileira de Tecnologia de Sementes (ABRATES)
Resumo
O angico-de-bezerro (Piptadenia moniliformis Benth.) é uma espécie arbórea melífera, de crescimento rápido, característica da caatinga do nordeste brasileiro, onde é muito abundante e com dispersão contígua e irregular. Seus ramos finos, junto com as folhas, servem como alimento para animais. Como suas sementes apresentam dormência por impermeabilidade do tegumento à água, objetivou-se neste trabalho avaliar a eficiência de tratamentos pré-germinativos para superar a dormência de suas sementes visando maximizar e uniformizar o processo de germinação. Foram estudados 28 tratamentos pré-germinativos: imersão em água a 70, 80, 90 ºC e fervente por 1, 2, 3, 4 e 5 minutos e imersão em ácido sulfúrico concentrado por 1, 5, 10, 15, 20, 25 e 30 minutos, além da testemunha. A semeadura foi realizada sobre papel em temperatura alternada de 20-30 ºC, utilizando-se quatro repetições de 25 sementes. Foram avaliadas as porcentagens de germinação das sementes considerando a protrusão da raiz primária, de plântulas normais e de sementes duras e o índice de velocidade de germinação. O delineamento experimental utilizado foi o inteiramente casualizado e as médias comparadas pelo teste de Scott-Knott a 5% de probabilidade. Os tratamentos de imersão em água, independentemente da temperatura e do período de imersão, aumentaram a porcentagem de germinação das sementes, comparativamente ao tratamento controle, mas foram menos eficientes que os tratamentos em ácido sulfúrico nos maiores períodos de imersão. Desta forma, a imersão por 20, 25 e 30 minutos em ácido sulfúrico é recomendada para a superação da dormência de sementes de Piptadenia moniliformis Benth.
The rapidly-growing honey-tree species Piptadenia moniliformis Benth. is typical of the Brazilian northeastern caatinga (scrubland), where it is found abundantly, contiguously and irregularly dispersed. The thin branches and leaves of this tree are used as animal fodder. The seeds of P. moniliformis present dormancy due to the seed-coat being impermeable to water. We evaluated the efficiency of pre-germinating treatments to overcome P. moniliformis dormancy and maximize and uniformize germination. A total of 28 pre-germination treatments were investigated: immersion in water at 70 ºC, 80 ºC or 90 ºC; boiling for 1, 2, 3, 4 or 5 minutes; immersion in concentrated sulfuric acid for 1, 5, 10, 15, 20, 25 or 30 minutes; and no treatment (control). After treatment, seeds were sown on paper and incubated at alternating temperatures of 20 ºC-30 ºC. Four replicates of 25 seeds were used for each treatment. The factors evaluated were: percentage of seeds with primary root protrusion; percentage of normal seedlings; percentage of hard seeds and the speed of germination index. The experimental design was completely randomized and the means were compared using the Scott-Knott test at a probability of 5%. Immersion in water, independent of the temperature and immersion period, increased germination as compared to control seeds but was less efficient than the longer periods of immersion in sulfuric acid. Thus, the immersion in sulfuric acid for 20, 25 and 30 minutes is recommended for the overcoming of Piptadenia moniliformis Benth. seeds.
The rapidly-growing honey-tree species Piptadenia moniliformis Benth. is typical of the Brazilian northeastern caatinga (scrubland), where it is found abundantly, contiguously and irregularly dispersed. The thin branches and leaves of this tree are used as animal fodder. The seeds of P. moniliformis present dormancy due to the seed-coat being impermeable to water. We evaluated the efficiency of pre-germinating treatments to overcome P. moniliformis dormancy and maximize and uniformize germination. A total of 28 pre-germination treatments were investigated: immersion in water at 70 ºC, 80 ºC or 90 ºC; boiling for 1, 2, 3, 4 or 5 minutes; immersion in concentrated sulfuric acid for 1, 5, 10, 15, 20, 25 or 30 minutes; and no treatment (control). After treatment, seeds were sown on paper and incubated at alternating temperatures of 20 ºC-30 ºC. Four replicates of 25 seeds were used for each treatment. The factors evaluated were: percentage of seeds with primary root protrusion; percentage of normal seedlings; percentage of hard seeds and the speed of germination index. The experimental design was completely randomized and the means were compared using the Scott-Knott test at a probability of 5%. Immersion in water, independent of the temperature and immersion period, increased germination as compared to control seeds but was less efficient than the longer periods of immersion in sulfuric acid. Thus, the immersion in sulfuric acid for 20, 25 and 30 minutes is recommended for the overcoming of Piptadenia moniliformis Benth. seeds.
Descrição
Palavras-chave
coat dormancy, Forest seed, Germination, Sementes florestais, dormência tegumentar, Germinação
Como citar
Revista Brasileira de Sementes. Associação Brasileira de Tecnologia de Sementes, v. 32, n. 2, p. 49-58, 2010.