This study aims to analyze the maturation and dispersal of Eugenia pyriformis Cambess. seeds produced in different years, and the influence of variation in thermal and hydric environment on seed physical and physiological characteristics at dispersal. Fruits at different developmental stages were harvested in the city of São Paulo between 2003 and 2010, as well as in the cities of Campinas and Lavras, in 2009 and 2010 and analyzed for size and color. The seeds were extracted from the fruits and their dry mass, water content, germination and vigor were assessed. Results showed that seed maturation is unsynchronized to the maturation of the fruit, taking 45 days on average (430 growing degree-days), longer in rainy times or lower temperatures. Seeds with higher physiological quality were produced in rainy years and when the temperature range was larger. We concluded therefore that hydric and thermal environmental variations during development influence the maturation of Eugenia pyriformis seeds and are able to determine the formation cycle and the final seed quality.

-Seeds of Eugenia pyriformis may produce several seedlings after cutting. Both the type of cutting and the size of the seed can determine the success in obtaining new seedlings. The size of the seeds is dependent on both the number of seeds per fruit and the conditions in which seeds develop, as well as the biometric characteristics of these seeds obtained from different regions and seasons. The seeds from each origin were evaluated in length, width, thickness, water content and dry mass, as well as the average number of seeds per fruit. From one of the regions, seeds were grouped according to the number of seeds per fruit and also according to their size, and then cut into two and four parts, and then analyzed for the fragments germination. The results demonstrated the high capacity of these seed fragments to produce new seedlings, but the capability reduces with the reduction in seed size. This size depends not only on the number of seeds per fruit, but also on the region and the period of the seed production.Index terms: germination, seed cutting, Myrtaceae, uvaia.O sucesso da germinação de sementes fracionadas de Eugenia pyriformis depende do seu tamanho e da sua origem RESUMO -Uma semente de uvaieira (Eugenia pyriformis) pode produzir várias plântulas quando fracionada. A posição do corte e o tamanho da semente influenciam o sucesso da obtenção de novas plântulas. O número de sementes por fruto e as condições nas quais as sementes se desenvolvem podem promover diferenças nesse tamanho. No presente trabalho foram analisados o grau de influência do número de sementes por fruto sobre a capacidade das sementes de uvaieira em germinar após fracionamento e os aspectos biométricos de sementes de uvaieira obtidas em diferentes regiões e épocas. As sementes de cada origem foram avaliadas quanto ao comprimento, largura, espessura, conteúdo de massa fresca e seca e teor de água. De uma das regiões, sementes foram agrupadas segundo a quantidade de sementes por fruto e também segundo seu tamanho e, a seguir, foram fracionadas em duas e quatro partes e analisadas quanto à capacidade germinativa dos fragmentos obtidos. Os resultados demonstraram a elevada capacidade dos fragmentos dessas sementes em formar novas plântulas, mas tal capacidade reduz concomitante à redução no tamanho da semente. Esse tamanho depende não apenas do número de sementes por fruto, mas também da região e da época de produção das sementes.Termos para indexação: germinação, fracionamento de semente, Myrtaceae, uvaia.