Low Temperature Storage of Caryopses of Triticum durum: Viability and Longevity

Germination of Triticum durum Desf. ‘Cappelli’ caryopses stored in hermetically-sealed containers at 10°C or −20°C was analysed. Caryopses were maintained in laboratory conditions (20±4°C) prior to controlled storage, which began 5d, 240d and 7 years after harvesting. In addition, after 9 years of storage, one 10°C stored batch of caryopses and two −20°C stored batches were returned to laboratory conditions. Germination over time and seed longevity were investigated. Results showed that: (1) under laboratory conditions, caryopses in relative (primary) dormancy at the beginning of storage had lost dormancy after 45d and germination ability was lost by the end of year 7. (2) When stored at 10°C, relative dormancy in caryopses was lost within 1 year, but 100% germination ability was retained after 23 years of storage. (3) When stored at −20°C, caryopses that were dormant at the beginning of storage (5d after harvesting) maintained this condition for 23 years while caryopses which were placed in storage 240d after harvesting, when relative dormancy had already been broken, maintained 100% germination ability. Caryopses returned to laboratory conditions after 9 years of storage at 10°C or −20°C showed the same trend as caryopses maintained exclusively in laboratory conditions since the time of harvesting. Caryopses removed from −20°C overcame relative dormancy in 50d and maintained germination ability for roughly 7 years, while those removed from 10°C lost the ability to germinate by the end of the fifth year.