Qualidade fisiológica de sementes e tamanho de amostra de azevém submetido a manejos de pastejo animal

• Autor(a) principal: Müller, Caren Alessandra
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Manancial - Repositório Digital da UFSM
• dARK ID: ark:/26339/0013000007257
• Texto Completo: http://repositorio.ufsm.br/handle/1/23186
• topic: Dimensionamento amostral; L. multiflorum; Posicionamento na espiga; Sample sizing; Lolium multiflorum; Spike positioning; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA

Ryegrass (Lolium multiflorum Lam) is used worldwide as pasture for animal feed, is considered one of the best pastures to supply the forage shortage during the winter period in the Rio Grande do Sul. Seed production usually occurs in specific areas for this purpose and those submitted to animal grazing, which can result in low physiological quality. The objective of this study was to study the physical and physiological quality of ryegrass seeds from different positions on the ear, harvested with different degrees of physiological maturity and submitted or not to continuous stocking animal grazing for 90 days, as well as to determine the sample size, in a number of plants, for characters morphological and productive. Ryegrass ears were harvested at random, in two areas of 10 hectares each, at 13, 20, 27, 31 and 35 days after 50% of the plants were in anthesis (DAA), is divided into upper, middle and lower thirds, proportional to the size of the ear, in areas with and without animal grazing, considering for the analysis of variance, a factorial 5 x 3 x 2. The seeds were submitted to the germination pattern, length of the aerial part and root, dry mass of seedling and mass of a thousand seeds. Plants were also collected and measured to evaluate morphological and productive traits: plant height, fresh and dry plant mass, number of ears per plant, ear size, number of spikelets per ear and plants per square meter, to perform the dimensioning sample through an iterative process with 2000 resamples with replacement. There was an interaction between the factors for the evaluated characters, with a higher index of germination speed, vigor and mass of a thousand seeds for the middle third of the ear at 27 DAA. The highest averages for seed germination were obtained for the upper and middle thirds at 27 and 31 DAA, in the area without animal grazing. In the grazed area, the highest germination was obtained at 35 DAA, with a delay in maturation in relation to the non-grazed area. The sample size of 306 and 218 plants, for areas with and without animal grazing, respectively, are sufficient to evaluate ryegrass morphological and productive characters. Continuous animal grazing decreases the physiological quality of seeds and the mass of a thousand seeds, occurring physiological maturity between 27 and 31 DAA in the area without animal grazing and between 31 and 35 DAA in the area with animal grazing.