Ontogenia dos órgãos reprodutivos e da plântula de Syagrus inajai (Spruce) Becc. (Arecacae)

Abstract

Syagrus inajai is a palm that occurs in the Amazonian Biome, in different plant physiognomies, such lowland rain forest, slope and gallery forests, as well as in open areas such as clearings and roadsides. It produces large quantities of edible fruits. The purpose of this work is to carry out an ontogenic study of S. inajai from gynoecium to seedling, in terms of its its morphoanatomy. The observations and collection of botanical material were carried out in 2009 and 2010, in a green area of the Campus of the Universidade Federal do Amazonas - UFAM, Manaus, Amazonas, Brazil, which is situated in a region of baixio forest, at coordinates 3 0 05’ 45.84” S and 59 0 58’ 43.69 ”. Thirty individual specimens of S. inajai were collected for analysis. The aim of the first chapter is to characterize the morphoanatomy of the inflorescence of S. Inajai, enabling a better knowledge of the species studied and an understanding of the processes of formation of the fruit and seed. The inflorescences are branched to one order, pedunculate, and interfoliar, measuring 62-82 cm in length, with woody bracts with longitudinal grooves on the external surface, and flowers in triads. The number of flowers to each inflorescence varies from 5,904 to 17,316 for staminate flowers, and from 180 to 3,528 for pistillate flowers. Staminate flowers with six stamens and one vascular bundle each; three-lobed pistillodium, vascularized pistillodium. Its pistillate flowers have six staminodia joined to form a circle, syncarpic, tricarpellary, trilocular gynoecium, one ovule to each locule, synascidiate in the ovary, and plicated above. Tripartite stigma, apical and sessile, with epidermis composed of elongated papillary cells, pattern of epidermis that is maintained throughout the stylar canal. Bitegmented, anatrope, pachychalazal ovule. In the second chapter, the aim was to carry out a morphoanatomical study of the development, from gynoecium to the developed fruit, and to measure the approximate time to occurrence of the separate events in this process. From the seminal primordium, the ovules are anatropous. Hypostasis with cells containing phenolic content is prolonged during development, including the entire ovule, throughout the length of the pachychalazy. The ovary has two meristemic regions: a peripheral meristem region, adjacent to the outer epidermis, which gives origin to the fibrous mesocarp; and an internal meristemic region, which involves the internal seminal cavity and is responsible for the thickening of the endocarp, forming the endocarp sensu lato, of mixed origin. Sclerification of the endocarp initiates in the fruit at around 80 days, occurring centripetally. The endosperm is of the multicellular coenocytic type, with formation of the cell walls occurring centrifugally. The operculum is comprised of cells of the outer and inner integuments, and by sclerified cells of the obturator. The first cell division of xi the zygote occurs around 30 days after the start of development of the endosperm. The development time of the fruit is approximately 240 days. The third chapter gives a morphoanatomical characterization of the embryo of Syagrus inajai, in different phases of its development, seeking to contribute with information on the embryonic development of palms, and further our understanding of the germinative process of plants of the family Arecaceae.The development process of the embryo, until the moment of dispersion, takes approximately 220 days, and is divided into four stages: proembryo, globular embryo, lateral cordiform and torpedo. The embryo is small, linear, and derived from the terminal cell of the proembryo, arising from mitotic divisions in the apical cell. The embryonic axis is located in the proximal region, aligned parallel to the length of the embryo. The single cotyledon is formed by the ground meristem, procambium and protoderm. The procambium supplies the embryonic axis and the haustorium. The fourth chapter aims to describe the morphoanatomy of the germinative process of S. inajai and to determine its average duration, and also to identify the ergastric substances present in the embryo, haustorium and endosperm, and to perform centesimal analysis of the seed.The germination of S. inajai starts at around 101 days after seeding, with the formation of the germinative button. The morphological events that followed were: lengthening of the hyperphyll, intumescence of the cotyledonary sheath, emergence of the primary root and first cataphyll, emergence of the second cataphyll and eophyll. Lengthening of the embryo axis was observed after the emergence of the germinative button, during the process of lengthening of the hyperphyll. It was possible to see the primary root with the naked eye after the intumescence of the cotyledonary sheath, at which moment the two cataphylls and the eophyll were differentiated in the cotyledonary sheath. Starch was observed in the embryo before germination, but its quantity increased in the parenchyma cells after the formation of the germinative button. The seed presented 30% lipids in its concentration at the moment of dispersion. The time from opening of the peduncular bract to dispersion of the fruit is 240 days. The opening of the pistillate flower occurs 20 days after the opening of the peduncular bract; the fruit takes around 240 days to form, and the embryo 220 days.