Estratégia de propagação sexuada e assexuada de Tanaecium bilabiatum coletado em pastagens do Amazonas

Abstract

Tanaecium bilabiatum (Sprague) L.G. Lohmann popularly known as “gibata” or “chibata” is the most important toxic plant for herbivores in the floodplain regions of the Amazon Basin and the second in importance in the entire region. The objective of this work was to study the characterization of the sexual and asexual propagation of T. bilabiatum occurring in the Amazon pastures, through morphological and histochemical studies of the reserves, to understand the dynamics of its population and continuity of the species. Phenological observations and collection of botanical and propagative material were carried out in three floodplain pastures in the Municipality of Parintins – AM, with samples of underground propagules being collected, removing the root system of three different plants and ripe fruits at different times, collected close to the dehiscence. Seed biometrics were obtained from a random sample, free from stunting, impurities, injuries and insect attack; for each of the variables analyzed, the means, standard deviation and range of variation were calculated. The seeds were sown to evaluate and describe the germination process and seedling development. The characteristics of fruits, seeds and seedling development were observed and photographed in greater detail, with the aid of a magnifying glass and stereoscope; The terms and characters analyzed in this work were the most used in morphological characterization studies. From the root systems of adult plants, portions of 8.0 cm in length, with diameters of 20, 10 and 5 mm were sectioned; the portions (cuttings) were sown in floodplain soil substrate; in a completely randomized experimental design (DIC), with three treatments related to diameters, 10 replications, with one cutting per replication, totaling 36 experimental units. The variables observed were the percentage of emergence and the average time of emergence; The Chi-Square Test (χ2) was also applied to verify the association between shoot emergence and root emission. Histochemical studies of sexual and asexual propagules were carried out with material fixed in neutral buffered formalin and preserved in 70% alcohol. Histochemical tests were performed using cross-sections of the propagules included in historesin. Tanaecium bilabiatum enters the reproductive phase when the water rises. Seed dispersal is autochoric/hydrochoric and ends with the descent of water. From viable seeds, polyembryonic seeds can develop, and the main reserve substances observed were starch and proteins. The cuttings can form stem and root shoots in all tested diameters and have starch as a reserve substance. The underground propagules of T. bilabiatum do not present morphological and anatomical characteristics of rhizomes or xylopodia, they are characteristic of roots and can be considered germinal roots. It was observed that young plants originating from seeds and underground cuttings have distinct morphological characteristics.