Tese (Doutorado) - Universidade Federal de Viçosa, Departamento de Fitotecnia, Programa de Pós-Graduação em Fitotecnia, 2018.

Abstract: Tithonia diversifolia (Hemsl.) A. Gray and Cratylia argentea (Desvaux) O. Kuntze are classified as multipurpose shrubs that are adapted to tropical environments and have a high regrowth capacity. They are species with promising use in the rural properties, considering their adaptations in restrictive environments and their versatilities in relation to the use especially because they stand out as green fertilizers and forages with high protein content. T. diversifolia is easily multiplied by asexual propagation, however, information on the sexual propagation in the species is scarce. C. argentea, although native, is a species conserved and evaluated in few active germplasm banks in Brazil, none of which is present in the Amazon. In this context and in order to contribute to the conservation and dissemination of the species, two studies were carried out. In the first one the objective was to evaluate the physiological quality of T. diversifolia seeds as a function of harvesting time, time and storage conditions. In the second, the objective was to carry out the prospecting of accessions of C. argentea in Brazil and to implant an active germplasm bank in the Amazon. In the work of T. diversifolia achenes were collected on different days after the anthesis (4, 16, 18, 20, 22, 24, 28, 32, 36 and 40 days) of the inflorescence. After the harvest, the following variables were evaluated: seed dry matter mass, germination percentage, germination speed index, germination speed and percentage of full achenes. Additionally, these variables were analyzed as a function of two storage conditions (refrigerated and non-refrigerated environment) and two storage times (6 and 12 months). Already for the work of C. argentea were collected excursions in 6 units of federation of Brazil to identify individuals of the species, description of the environment of the individuals insertion and seed collection. The seeds collected were used to produce seedlings that were used for implantation of an active germplasm bank in the Amazon. The ideal harvest period of T. diversifolia seeds comprised the period between 28 and 36 days after anthesis, where seeds with germination percentages higher than 75% and percentage of achenes full of 100% were obtained. The chilled environment provided the highest percentages of seed germination, in addition, the germination speed and the rate of germination decreased and ncreased over the storage time, respectively. The seeds presented a high percentage of germination after 12 months of storage in both refrigerated and non -refrigerated conditions. For C. argenetea, 32 accessions were obtained in the states of Acre, Ceará, Goiás, Maranhão, Pará and Tocantins. The species was identified in the Amazon, Cerrado and Atlantic Forest biomes in a range of 102 to 762 meters of altitude. At the Federal University of Acre, in Cruzeiro do Sul (Acre - Brazil) and the Amazon biome, an active germplasm bank was implanted with 140 plants of all the accesses collected.

Orientadora Denise Cunha Fernandes dos Santos Dias