Low temperature storage of caryopses of Triticum durum: Viability and longevity

Abstract

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 5 d, 240 d 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 45 d 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 (5 d after harvesting) maintained this condition for 23 years while caryopses which were placed in storage 240 d 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 50 d 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. (C) 2000 Annals of Botany Company.