The study aimed to verify the physiological quality of seeds of Myrciaria dubia, stored for 300 days in different conditions and packaging, using tests of electrical conductivity and seedling vigour. The seeds were classified into three weight classes (small, medium and large). Small seeds were considered those with a weight of less than 0.84 g, medium seeds with a weight between 0.86 g and 1.20 g, and large seeds, a weight of greater than 1.22 g. The seeds were stored in glass containers and plastic pots topped up with water, in the laboratory at a room temperature of 23 to 25°C and relative humidity of 60-70%, and in a cold chamber at a temperature of 14-16°C and relative humidity of 50-60%. For each storage period (0, 30, 60, 120, 180, 240 and 300 days), a sample of 110 seeds was used for analyses, including imbibition curve, seed dry weight, electrical conductivity, seedling emergence and emergence speed index. The responses of the seeds in both the laboratory and cold-chamber, and stored in plastic pots topped up with water, are indicated for maintaining physiological quality and seedling vigour up to 300 days.