Seed anatomy and germination of Phoenix roebelenii O'Brien (Arecaceae)

Abstract

-The objective of this study was to investigate the morphology, anatomy and germination behaviour of Phoenix roebelenii seeds. Biometric data were obtained by measuring 100 seeds extracted from recently harvested fruits and air-dried for one day. Four replications of 50 seeds each were previously treated with Vitavax-Thiran and then put to germinate in Sphagnum sp. in plastic trays at room temperature. Morphological details of the seeds were documented with the help of a scanning electronic microscope and then drawings were made with the help of a clear camera coupled to a stereomicroscope. Permanent lamina containing embryo sections were prepared to study its anatomy. The mean dimensions of the seeds were: length of 10.32mm, width of 5.21mm and thickness of 3.91mm. The weight of one thousand seeds was of 151.1g and the mean number of units.kg -1 was 6,600. Germination started between 27 and 58 days after sowing. The seeds are of the albuminous type, the endosperm is hard and the embryo (which is not clearly differentiated) occupies a lateral and peripheral position. During seed germination, seedling protrusion begins with the opening of an operculum, through which the cotyledon petiole is emitted with the embryonic axis at its tip. The portion of the cotyledon petiole that remains inside the seeds acts as a haustorium for the absorption of nutrients from the endosperm. The plumule emerges through a rift in the posterior part of the cotyledon. Secondary roots are observed to grow from the anterior part of the primary root.Index terms: palm, pigmy date palm, pyrene, seedling. ANATOMIA E GERMINAÇÃO DE SEMENTES DE Phoenix roebelenii O'Brien (ARECACEAE)RESUMO -O objetivo desse trabalho foi estudar a morfologia, anatomia e o processo germinativo de sementes de Phoenix roebelenii. Para o levantamento dos dados biométricos foram utilizadas 100 sementes de frutos recém-colhidos, deixados secar ao ar por um dia. Para a germinação, quatro repetições de 50 sementes tratadas com Vitavax-Thiran foram semeadas em bandejas de plástico, contendo Sphagnum sp. como substrato e mantidas sob condições ambientais de laboratório. Detalhes da morfologia da semente foram documentados com o uso de microscopia eletrônica de varredura e esquematizados com auxílio de câmara clara, acoplada ao estereomicroscópio. Foram confeccionadas lâminas permanentes com cortes do embrião, para o estudo de sua anatomia. As dimensões médias das sementes foram: 10,32mm comprimento, 5,21mm largura e 3,91mm espessura. O peso de 1000 sementes foi de 151,1g e 1kg continha 6600 unidades. O início da germinação variou entre 27 e 58 dias. As sementes são albuminosas, com endosperma duro e o embrião é pouco diferenciado, lateral e periférico. A germinação inicia-se pela abertura de um opérculo, através do qual é emitido o pecíolo cotiledonar com o eixo embrionário na extremidade. O pecíolo funciona, internamente, como um haustório, digerindo gradativamente o endosperma. Na sua parte posterior, desenvolve-se a plúmula, que emerge através de uma fenda. Nota...

Germinação de embriões zigóticos e desenvolvimento in vitro de coquinho-azedo

“…Asif et al, (2001) concluíram que a luz não afetou a germinação de embriões de Musa acuminata, porém, o cultivo no escuro atrasou a emissão da parte aérea e favoreceu o enraizamento. A emissão de raízes deve ser considerada como variável chave para a avaliação da cultura de embriões de palmeiras (Melo, 2000), uma vez que, em várias espécies, ocorre a imaturidade do embrião, relacionada com a indiferenciação da radícula, como em Washingtonia filifera (Demason, 1988), Euterpe precatoria (Aguiar & Mendonça, 2002) e Phoenix roebelenii (Iossi et al, 2006). Melo et al (2001) não obtiveram enraizamento em plântulas de guarirobeira até os 110 dias de cultivo.…”

Carpological analysis ofPhoenix(Arecaceae): contributions to the taxonomy and evolutionary history of the genus

“…Date fruits are ellipsoidal to ovoid or almost cylindrical. Dimensions of dates are variable, ranging from 10 × 5 mm in P. roebelenii O'Brien (Iossi, Vitti & Rubens, ), to 75 × 35 mm in P. dactylifera ‘Medjool’.…”

Structural evaluations of zygotic embryos and seedlings of the macaw palm (Acrocomia aculeata, Arecaceae) during in vitro germination

“…The germination in many species is dependent on seed treatments that promote post-abscission embryonic development (Baskin and Baskin 1998;Hartmann et al 2002). Demason (1988a) observed that the root pole of the embryo of W. filifera was less developed that it was not possible to determine the inclination of the embryo axis; similar situations were reported for Euterpe precatoria (Aguiar and Mendonça 2003) and Phoenix roebelenii (Iossi et al 2006). Additionally, root system development in species such as C. nucifera (Lédo et al 2007) and S. oleracea (Melo et al 2001) is difficult even when the embryos are cultivated in vitro, and requires hormonal stimulation.…”

“…Henderson (2006) pointed out that there are many morphological patterns in palm embryos and seedlings, and that germination processes could only be accurately described through a detailed association of morphological and anatomical characteristics. In spite of the fact that there has been a certain amount of published research focusing on the structure and histochemistry of palm embryos (Demason and Thomson 1981;Demason 1988a;Panza et al 2004;Moura et al 2010), morphological characterization of the seedlings (Gentil and Ferreira 2005;Charlo et al 2006), and morphological and anatomical evaluations of the embryos and seedlings (Demason 1984(Demason , 1985Aguiar and Mendonça 2002;Henderson 2006;Iossi et al 2006) are still far from being complete (see Panza et al 2004).…”