Water absorption and physiological responses of hog plum tree diaspores to storage/Absorcao de agua e respostas fisiologicas de diasporos de cajazeira ao armazenamento

• Published in: Revista Brasileira de fruticultura Vol. 42; no. 3
• Main Authors: de Carvalho, Jose Edmar Urano, do Nascimento, Walnice Maria Oliveira
• Format: Journal Article
• Language: English
• Published: Sociedade Brasileira de Fruticultura 01-05-2020
• ISSN: 0100-2945
• DOI: 10.1590/0100-29452020573

Hog plum tree seeds (Spondias mombin L.) have a complex dormancy mechanism, which causes slow germination and great unevenness. At present, there are no efficient methods to promote seed germination. The objective of the study was to evaluate the effect of storage on overcoming seed dormancy of this Anacardiaceae. Diaspores of two hog plum trees were used, identified as Mother plant 1 and Mother plant 2, established in Tome-Acu city, PA. Initially, it was investigated whether the structures surrounding the seeds (internal mesocarp and endocarp) prevent water absorption. For this, the diaspores of the two mother plants were sown between blotting paper, with an adequate level of water and, periodically, in the total of 144 hours, the water content of the seeds was computed. The storage studies involved two experiments. In the first, diaspores from both mother plants with a water content of around 5.0% were stored in impermeable packages, for one year, under the following conditions: natural environment of Belem, PA (average temperature of 26.8 [degrees]C) and at temperatures of 6 [+ or -] 1 [degrees] C and minus 18 [+ or -] 2. The germinative response of the stored diaspores was compared with those of non-stored diaspores. Prior to storage, selection was made on the diaspores, discarding the small ones. In the second experiment, the germinative response of the diaspores of the two mother plants, stored for zero, one, two, three, four, five and six months, under natural environment conditions of Belem, PA, was evaluated. It was observed that the structures that cover the seeds do not offer restrictions to the water absorption, thus discarding the hypothesis of physical dormancy, without, however, excluding the possibility of mechanical dormancy. The storage of diaspores for one year, regardless of the storage condition, did not affect the germination power of the seeds. On the other hand, responses of great magnitude, in terms of reducing the time required for germination, were obtained when the diaspores were stored under natural conditions and at minus 18 [+ or -] 2 [degrees]C, indicating that dormancy is naturally overcome by storage . Overcoming dormancy was a little slower when the diaspores were stored at a temperature of 6[+ or -] 1 [degrees]C. It was found that the storage of diaspores in an environment with an average temperature of 26.8 [degrees]C for three months provides the overcoming dormancy of most of the seeds. The intensity of dormancy varied within and between mother plants. Index terms: Spondias mombin L., germination, dormancy. As sementes de cajazeira (Spondias mombin L.) apresentam complexo mecanismo de dormencia, que condiciona germinacao lenta e desuniforme. Presentemente, nao existem metodos eficientes para promover a geminacao das sementes. O objetivo do trabalho foi avaliar o efeito do armazenamento sobre a superacao da dormencia de sementes dessa Anacardiaceae. Foram utilizados diasporos de duas cajazeiras, identificadas como Planta matriz 1 e Plant matriz 2, estabelecidas no municipio de Tome-Acu-PA. Inicialmente, foi investigado se as estruturas que envolvem as sementes (mesocarpo interno e endocarpo) impedem a absorcao de agua. Para tanto, diasporos das duas plantas foram semeados entre papel mata-borrao, com nivel adequado de agua e, periodicamente, no total de 144 horas computou-se o teor de agua das sementes. Os estudos de armazenamento envolveram dois experimentos. No primeiro, diasporos de ambas as matrizes, com teor de agua em torno de 5,0%, foram armazenados em embalagens impermeaveis, durante um ano, nas seguintes condicoes: ambiente natural de Belem-PA (temperatura media de 26,8[degrees]C) e nas temperaturas de 6[+ or -]1[degrees]C e 18 [+ or -] 2[degrees]C negativos. A resposta germinativa dos diasporos armazenados foi comparada com as de diasporos nao armazenados. Antecedendo ao armazenamento, efetuou-se selecao nos diasporos descartando-se os de tamanho diminuto. No segundo experimento, considerou-se a resposta germinativa dos diasporos das duas plantas matrizes, armazenados nas condicoes de ambiente natural de Belem-PA, durante seis meses, e avaliados mensalmente. Observou-se que as estruturas que recobrem as sementes nao oferecem restricoes a absorcao de agua, descartando, portanto, a hipotese de dormencia fisica, sem, no entanto, excluir a possibilidade de dormencia mecanica. O armazenamento dos diasporos, durante um ano, independentemente da condicao de armazenamento, nao afetou o poder germinativo das sementes. Por outro lado, respostas de grande magnitude, em termos de reducao do tempo requerido para germinacao, foram obtidas quando os diasporos foram armazenados nas condicoes de ambiente natural e a 18 [+ or -] 2[degrees]C negativos, indicando que a dormencia e naturalmente superada pelo armazenamento. A superacao da dormencia foi mais lenta quando os diasporos foram armazenados a 6 [+ or -] 1[degrees]C. Constatou-se que o armazenamento dos diasporos nas condicoes de ambiente natural de Belem, durante tres meses, proporciona a superacao da dormencia da maior parte das sementes. A intensidade da dormencia variou dentro e entre plantas matrizes. Termos para indexacao: Spondias mombin L., germinacao, dormencia.