ABSTRACT
Studies on the germination and establishment of plants are key pieces to understanding the reproductive success of plants. This work aimed to describe in vitro germination and reserve mobilization in the bromeliad Vriesea friburgensis through morphological, histochemical, and biochemical analysis. The conditions used in this study for the in vitro germination are adequate. From the third day of in vitro inoculation, a uniform germination of 98% was obtained, exhibiting a high physiological quality of the seeds and a high potential to produce seedlings (94%). There is early reserve mobilization, which began in the imbibition phase. The accumulated reserves in the endosperm cytoplasm are degraded by hydrolytic enzymes provided by the aleurone layer. It is possible that compounds in the cell walls of the endosperm contribute to a lesser extent in mobilization. Additionally, it was observed that starch accumulation in the cotyledon increases when the seedling has formed. Results from this study provide insights for future studies on ecology, seed technology, and conservation in this species. This study contributes to the limited knowledge of the dynamics of reserves during germination and seedling establishment in Bromeliaceae. To the best of our knowledge, this is the first study with this approach in the genus Vriesea.
Subject(s)
Bromeliaceae , Germination , Germination/physiology , Seedlings/physiology , Seeds/physiology , Cotyledon/metabolismABSTRACT
Ananas ananassoides (Baker) L.B.Sm. is a wild pineapple, commonly found in the savannas. This study aimed to describe the morpho-anatomy and histochemistry of its seed. The observations were made in the longitudinal and transverse sections, using an optical microscope. The cell arrangement in the seed coat, ripples in the integument, the ratio of embryo size and endosperm amount, and the number of strata in the aleurone layer are anatomical characteristics that may contribute to distinguishing this species. The starch in the endosperm, lipids and proteins in the embryo, constitute the seed's main nutritional reserves. The homogeneous embryo and phenolic compounds present in the seed coat and in the aleurone layer possibly contribute to the dormancy in this species. This study presents information relevant to the taxonomy and physiology of A. ananassoides, which represents contributions to the global knowledge of this species with a high potential as ornamental.
Subject(s)
Ananas , Endosperm/metabolism , Grassland , Seeds/chemistryABSTRACT
RESUMO O gênero Aloe, originário principalmente da África, tem atualmente uma ampla distribuição no mundo. No entanto, são poucas as regiões que têm realizado estudos quanto ao sistema reprodutivo. O objetivo do presente trabalho foi analisar as características e o comportamento reprodutivo de Aloe saponaria em Florianópolis, Santa Catarina. Foram conduzidos estudos sobre sua morfologia e biologia floral, visitantes florais e sistema reprodutivo. Esta espécie apresentou uma inflorescência por planta, com um comprimento de 105 ± 0,1 cm e 267 ± 92,7 flores. A razão pólen/óvulo sugere que a espécie é xenogâmica. O volume e concentração de sólidos solúveis totais do néctar potencial foi 16,6 ± 6,3 μL e 22 ± 2,4 °Brix respectivamente. O néctar instantâneo não apresentou diferenças significativas nos períodos avaliados (9:00h e 15:00h) e o estigma permaneceu receptivo até o segundo dia após a antese. Foram coletados 110 insetos visitantes florais, dos quais 61,8% foram indivíduos de Trigona spinipes. Entretanto, nos testes de polinização não foi observada frutificação efetiva, indicando que a propagação vegetativa é o principal tipo de reprodução usado nessa população. Isto pode estar relacionado a um mecanismo de autoincompatibilidade esporofítica, a anormalidades cromossômicas durante a formação do pólen, as condições climáticas, e a escassa variabilidade genética no local de estudo.
ABSTRACT The Aloe genus, originating mainly from Africa, currently has a wide distribution in the world. However, in few regions studies about the reproductive system have been carried on. The aim e of this study was to analyze the characteristics and reproductive performance of the Aloesaponaria in Florianópolis, Santa Catarina. The morphology, floral biology, flower visitors and the reproductive system were determined. The plants presented an inflorescence per plant, with 105 ± 0,1 cm in length and 267 ± 92.7 flowers. The pollen/ovule ratio suggested that the species is xenogamic. The volume and concentration of total soluble solids in the potential nectar were 16.6 ± 6.3 μL and 22 ± 2.4°Brix, respectively. The instant nectar showed no significant differences between the evaluated periods (9:00h and 15:00h) and the stigma remained receptive until the second day the after anthesis. 110 insects were collected, from which 61.8% were from theTrigona spinipesspecies. However, in the pollination tests the fruit set was not observation, indicating that vegetative propagation is the main type of reproduction used by this population. This may be related to a mechanism of sporophytic self-incompatibility, to chromosomal abnormalities during the formation of pollen, to weather conditions, and to the low genetic variability at the study site.
