Cork-oak and stone-oak seed management aimed at implementing nursery production of seedlings

Cork-oak and stone-oak are important species for Mediterranean regions, where they play an important role in the economy of marginal areas. However, efficient reforestation is hampered by inadequate supplies of high quality seedlings. Oak seeds are recalcitrant and therefore cannot be desiccated. This hamper seed storage, as it would be necessary to sow acorns during the spring following harvest. The moisture content that seeds should not overcome to maintain high viability ranged from 35 to 37%. Below 15-18% moisture content acorns all died. Concerning seed storage, moisture content higher than 40% proved to be better than lower values, while temperature of 0°C was better than higher and lower temperatures. After 9 months of storage at 0°C, acorns with 42% moisture content were still fully viable. Although cork-oak and stone-oak seeds show a slight dormancy, stratification treatments proved not to be able to improve seed germination. Only in a few cases it was possible to speed up seed germination, but saved time is much less than treatment duration. Thermotherapy proved to be highly efficient in keeping under control insect infestation of seeds. Treatment in water at 45°C for 30 minutes killed all larvae present inside seeds while not decreasing seed germination performance.