Cold rice seeds live longer
IRRI’s Fiona Hay and colleagues have recently published research on the viability of rice (Oryza sativa) seeds stored under genebank conditions for up to 30 years. The study confirms that placing dry seeds at -20˚C extends their longevity.
They tested 183 types of rice out of more than 112,000 collections of rice seeds stored at the T.T. Chang Genetic Resource Center (see the International Rice Genebank) for their germination ability, equilibrium relative humidity (eRH), and moisture content. These include the safety duplicate samples sent to the National Center for Genetic Resource Preservation in Fort Collins, Colorado, USA in 1981. Their viability was compared to the same seed lots kept in the active collection (2-4˚C) and base collection (-10˚C until 1993, then -20˚C) at IRRI.
According to the research, germination of the seeds in the base collection was higher than those in active collection. Also, the mean eRH of the seeds stored in the base collection was significantly lower than those of the safety duplicate samples. This means that the samples acquired moisture which resulted in a faster rate of viability loss.
These findings could help promote further study on genebank management and its effectiveness in prolonging shelf life of rice seeds for long term use. Rice breeders depend on these collections to conserve genes of existing varieties and to further improve them.