Dormência, vigor e estabelecimento inicial de braquiária e alfafinha

• Autor(a) principal: Trombetta, Carlos Guilherme
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFPel - Guaiaca
• Texto Completo: http://repositorio.ufpel.edu.br/handle/ri/1420
• topic: Qualidade fisiológica; Brachiaria brizantha; Medicago polymorpha L.; Physiological quality; Brachiaria brizantha; Medicago polymorpha L.; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::PRODUCAO E BENEFICIAMENTO DE SEMENTES

The Brazilian agriculture, in order to achieve high levels of mass production on pastures, requires a prior planning in its installation, which is very important, because only then it will be possible to obtain fields without invasive plants and seeds, showing high force, appropriate germination and establishment in shortest possible time for the vegetative canopy. Among the problems faced for the appropriate installation of a pasture are the low quality of seed in purity and germination, as well as the presence of invasive weeds and the low force associate of seeds. On this base, the main objective of this research is to evaluate the physiological quality of the seeds of genus Brachiaria and Medicago, as well as the reply to the different managements proposed in order to overcome the dormancy. Three studies were performed: the first evaluated the physical and physiological quality, and vegetative growth in five different lots of Brachiaria brizantha cv. BRS Piatã, evaluating the reply to the stimulus of overcoming the dormancy and different tests of the evaluation of force, with the objective of evaluating the consistent observations to purity and germination expressed in different lots. The results disclosed that most of the lots show the minimum purity and they are in agreement to the laws, however expressing low crop value. The association with high temperature and cold stress potentiated in some lots the germination, with significant increase for the association to potassium nitrate for germination and force in many observations. The second study consisted on the study of seeds of Medicago spontaneously naturalized in the state of Rio Grande do Sul, to which proceeded the consistent evaluations of physiological quality of seeds, with the objective to analyze different methods of overcoming dormancy in seeds with coloring and time of contrasting storage and to infer the influence on physiological attributes related to seed force of alfalfa. The treatments used differed from the witness expressing that the species is responsive to treatments used, with the highest averages found to germination in treatments that use manual sandpaper, with the dark coloring showing higher germination than clear coloring in certain treatments. The third study consisted on the physiological quality and growth analysis in field conditions, for four commercial species of genus Brachiaria and one of genus Medicago in search of undertake analysis and identification of the materials with better performance in the establishment of vegetative canopy in conditions in the northern region of Rio Grande do Sul. The low perceptual of physiological quality of forage seeds found in this study shows the need to increase the research to identify genotypes with good force of germination index, to attend the growing demand of the farmer sector. The seeds of genus Brachiaria and Medicago can express high level of dormancy, harming the minimum quality standards required, save exceptions that reached above the minimum establishment standards, being the final consumer the responsible for requiring quality seeds.