Storing cork oak (Quercus suber) seeds under different temperatures and the effect of storage treatments on the germination and growth of stored seeds

The cork oak "Quercus suber L." is one of the most important forest trees in the world, especially in the Mediterranean Basin, due to its high environmental, socioeconomic, and landscape value throughout the year. In general, these trees face particular problems that affect their germination, growth, survival, and the other biotic and abiotic causes that affect natural regrowth.Thus, the most important of these problems is the annual irregularity in tree seed production. For this reason, The storage problems of this species are of concern to managers, who are using new alternative techniques to deal with the problem of the irregular annual production of oak seeds and to preserve them for as long as possible. The present work aimed to evaluate the effect of storing cork oak Quercus suber L. seeds at different temperatures and for different periods of up to 300 days on their vitality and ability to germinate. For this, the seeds were subjected to four storage parameters at four temperature levels: -0.5°C, -1°C, +4°C with thermotherapy, and +4°C without thermotherapy as a control from January 2019 to September 2019. Analysis of the obtained results showed that the treatments studied significantly affected the measured parameters. After 30 and 60 days, the results of the 4 treatments concluded that the fourth storage treatment (storage of seeds directly at +4°C) presented a good performance in terms of the length of the seedlings, which was high (52.45 cm), the production of seedlings with an average diameter of 5.28 mm, and the important germination percentage (88.57%), unlike the other treatments. After a storage period of 270 days, the fourth storage treatment, the control, stored at 4°C without thermotherapy, still showed the best growth and development. This treatment also achieved a higher germination percentage (17.14%), plant height (11.33cm), and average diameter (1.85 mm) than the other treatments.