The significant progress in Brazilian agricultural production has been due its capacity to incorporate and use genetic resources. Embrapa Genetic Resources and Biotechnology is the institution responsible for the long-term conservation of the seed germplasm of many crops, stored at -20 °C. Appropriate storage is necessary for correct germplasm management, to ensure the quality of the material stored and minimize the deterioration process. The objectives of this study were to evaluate the effect of seed water content on the tolerance to storage at sub-zero temperatures of -20 °C and -196 ºC, to associate the tolerance level with physiological and biochemical aspects and to verify the effect of the pre-humidification of seeds on physiological quality after storage. Seed quality was evaluated by tests of electrical conductivity, first and final count of germination and determination of the peroxide index. Sunflower seeds can be dried to 3.2% of water content in silica gel or in a drying chamber and stored at -20 °C or -196 °C without loss of germination and vigor. Seed deterioration, evaluated by the peroxide index, was lower in seeds stored in NL. The humidification treatment was important for the evaluation of seedlings in the first count of germination test and the electrical conductivity test.
germination; vigor; conservation; liquid nitrogen; cold chamber
