Dormancy and enzymatic activity of rice seeds stored in different environments

The objective of this study was to evaluate dormancy and enzymatic activity of seeds of rice cultivars during storage in different environments.  After harvesting, the seeds of two rice cultivars ( BRS Ourominas, BRSMG and BRSMG Caravera) were dried in the sun, to reach moisture content at around 13%. Then, they were packed in paper and stored in four environments: 5±2 °C / 70±5% RH, 12±2 °C/70±5% RH, 18±2 °C/65±5% RH and natural condition. Germination and enzymatic activity were evaluated at the beginning and at 3, 6, 9 and 12 months of storage.  The experiment was conducted in split split plots in a completely randomized design with three replications. The dormancy of seeds stored in the natural environment was exceeded in a shorter time than the dormancy of seeds stored in cold. Only seeds from Ourominas cultivar, regardless the environment, maintained germination above the minimum required for commercialization until six months of storage. Catalase and ascorbate peroxidase activity increased during storage period and α-amilase activity were higher in the beginning and at 3 months of storage.