425 DRYING RATE AFFECTS SEED VIABILITY OF M. OVATA * Author for correspondence José, A.C., da Silva, E.A.A., Davide, A.C., Melo, A.J.S. and Toorop, P.E. (2011), Seed Sci. & Technol., 39, 425-434 Effects of drying rate and storage time on Magnolia ovata Spreng. seed viability A.C. JOSÉ 1 , E.A.A. DA SILVA 1,2 , A.C. DAVIDE 1 , A.J.S. MELO 1 AND P.E. TOOROP 3 * 1 Departamento de Ciências Florestais, Universidade Federal de Lavras, Lavras, MG, Brazil. Cx Postal 3037, CEP 37200-000 2 Current address: Faculdade de Ciências Agronômicas, Departamento de Produção Vegetal, Universidade Estadual Paulista, Botucatu, SP, Brazil. Cx Postal 237, CEP 18603-970 3 Seed Conservation Department, Royal Botanic Gardens Kew, Wakehurst Place, Ardingly, West Sussex, RH17 6TN, United Kingdom (E-mail: p.toorop@kew.org) (Accepted November 2010) Summary Magnolia ovata seeds have been reported as desiccation sensitive. In order to test if the drying rate would affect the assessment of storage behaviour of these seeds, the effect of different drying rates and storage times on the viability was tested. Seeds were dried over activated silica gel (fast drying) or salt solutions for different periods (slow drying) and stored at -20°C. Partial drying transiently increased the final germination and the germination speed index, but further drying resulted in reduction of these parameters. Drying rate affected the final germination and vigour. Seeds that were slow-dried to 0.10 g H 2 O • g -1 dw retained high viability when compared with seeds desiccated to the same water content level by the fast drying method, although their vigour was reduced. Only slow-dried seeds could be stored at -20°C for 90 d without reduction of viability. These data suggested that the storage behaviour of seeds of M. ovata seeds should be classified as intermediate. Introduction Forest genetic resources are being threatened in various Brazilian ecosystems as a result of deforestation. The development of strategies for conservation and restoration of such degraded forests depends on the knowledge of plant propagation of the species that constitute these biomes, including seed germination and seedling growth. Many species produce seeds that can be stored for a long time and are available for use throughout the year. However, some plant species produce short-lived seeds, especially those originating from the tropics. Information about proper storage conditions and the potential storage time of seeds contributes to the success of plant conservation and in situ restoration. Seeds can be sorted in three groups according to desiccation tolerance and storage conditions. Those that are tolerant to a low water content (lower than 0.10 g H 2 O • g -1 dw) and storage at a low temperature (usually -20°C) are considered desiccation tolerant and