The effect of storage temperature and duration on northern red oak acorn viability and vigour

Three separate collections of Ontario sources of northern red oak (Quercus rubra L.) acorns were made to determine the effects of long-term cold storage at +2°C, −1°C, and −2°C on their viability and vigour. We measured acorn moisture content, percent germination during storage, speed of germination and total germination values, root regrowth of seeds that germinated in storage, incidence of fungal contamination, and condition of ungerminated acorns. Viability and vigour peaked six to 12 months after acorns were placed in storage, but decreased with continued storage. After 18 months in storage, ≥60% of the acorns germinated in four of the five seedlots tested and, after 30 months in storage, ≥53% of the acorns germinated in three of the five seedlots tested. Acorn viability was only minimally affected by storage temperature; however, since temperatures above −2°C allowed acorns to germinate during storage, the preferred long-term storage temperature was −2°C. Our results suggest that, assuming proper storage conditions, most red oak seedlots will maintain relatively high germination levels when stored at −2°C for 18 months. Seedlots with particularly high initial germination and vigour may be successfully stored for up to 30 months.