Exploring CGIAR’s viability monitoring data
CGIAR Centers have viability records dating back more than thirty years. If you do not work in a CGIAR Center, it is still instructive to look at how these genebanks have managed to maintain the viability of seeds in their collections, and to learn from their records about how different species behave in storage.
Activity 2
Allow 15 minutes for this activity.
Figure 12 (below) shows the viability monitoring data for rice, Oryza sativa in long-term storage (LTS) and medium-term storage (MTS) in two different CGIAR Centers: Africa Rice and IRRI. Take a look at the data: what does it tell you?
Use the note-writing box below to explain what these data tell you about viability of this type of rice in Africa Rice and IRRI.
When you are ready, press 'reveal' to see our comments.
Discussion
IRRI is a long-established Center, which has been keeping records for decades, whereas Africa Rice is newer. This explains why there are more data for IRRI than Africa Rice. Germination rates following medium-term and long-term storage vary, with a few falling below the Genebank Standards’ recommended threshold, but many are above p85. Overall, the data from IRRI shows that high viability has been maintained for many seed lots, over a period of decades, in both medium-term and long-term storage. The results compare well with other studies in the literature.
Not all species and genera are as easy to store as Oryza sativa. Some crops (e.g.: banana) cannot be stored because seeds are not the primary propagation method. Other crops (e.g.: avocado) produce recalcitrant seeds. In future, cryopreservation could offer an interesting conservation opportunity for crops like these. However, even among crops that do produce seeds that can be stored in seed genebanks, there are some whose seeds are more difficult to store than others.
Look at Figure 13, which shows a CGIAR Center’s monitoring data for peanut, Arachis hypogaea in long-term storage (LTS) and medium-term storage (MTS):
Use the note-writing box below to explain what these data tell you about viability of Arachis hypogaea.
When you are ready, press 'reveal' to see our comments:
Discussion
The data for medium-term storage show a lot more variation in viability for this particular type of groundnut than you see in other crops. The results of germination tests vary a lot. Paradoxically, this effect is less obvious in long-term storage of Arachis hypogaea. This shows we cannot be complacent about some crops, even in international genebanks – there is still a lot for us all to learn!
Despite differences between crop species, the CGIAR viability data gives reasons for optimism about the effectiveness of genebank operations:
- Genebank conditions maintain viability well (enough) for most crop species.
- Given predicted and achieved longevity of seeds of the various crop species, regeneration is primarily due to low seed number, often at harvest, rather than loss of viability.
- We need to optimize the quantity of seeds produced and placed into storage to represent an accession, and to base decisions about how many seeds to store on expected demand - if there is any demand.
- For some species, which are relatively short-lived, we may be approaching ‘steady state’ operations; however, for many species, genebanks are still too ‘young’ to be certain of what longevities can be achieved.
- It is important to continue monitoring older seed lots, maintaining previous viability testing intervals, or even shortening them, to get a better understanding of longevity in genebank storage.
Viability testing