Page compiled by: Bioversity International/ILRI, Addis Ababa, Ethiopia (Alexandra Jorge); ILRI, Addis Ababa, Ethiopia (Jean Hanson) including information extracted from: Rao NK, Hanson J, Dulloo ME, Ghosh K, Nowel D and Larinde M. 2006. Manual of seed handling in genebanks. Handbooks for Genebanks No. 8. Bioversity International, Rome, Italy. 147pp.
What is germplasm monitoring
Germplasm monitoring is the regular checking of the quality (the viability) and the quantity (the existing stocks in number or weight) of seeds or plant materials of germplasm accessions stored in a genebank.
Why should accessions be monitored
To avoid excessive deterioration of seed (or plant material) quality or quantity, genebank accessions should be monitored both for viability and seed (or plant material) quantity during storage. There are two main reasons to monitor the accessions:
- The viability of seeds (or the plant material) stored in a genebank decreases during storage. It is therefore important to monitor their viability to ensure that they do not lose their capacity to produce viable plants when needed.
- The removal of seeds or plant material for distribution and germination testing, results in a decrease of seeds or plant material over time. It is important to know how much material is in stock to avoid using all material before regeneration is completed.
- Germplasm accessions identified with low viability or inadequate quantity during the course of monitoring should be regenerated as soon as possible using the methods described in the general or crop sections on regeneration.
The monitoring interval for quality depends on the species, storage environment (seed moisture content and temperature), risk in the field genebank for plants in the field and seed viability or number of plants at the start of the storage period. For seed genebanks the FAO Genebank Standards (2013) recommend that:
- The initial seed viability test should be conducted after cleaning and drying the accession or at the latest within 12 months after receipt of the sample at the genebank.The initial seed viability test is conducted after cleaning and drying the accession or at the latest within 12 months after receipt of the sample at the genebank.The initial seed viability test is conducted after cleaning and drying the accession or at the latest within 12 months after receipt of the sample at the genebank.
- The initial germination value should exceed 85 percent for most seeds of cultivated crop species. For some specific accessions and wild and forest species which do not normally reach high levels of germination, a lower percentage could be accepted.
- Viability monitoring test intervals should be set at one-third of the time predicted for viability to fall to 85 percent or lower depending on the species or specific accessions] of initial viability but no longer than 40 years. If this deterioration period cannot be estimated and accessions are being held in long-term storage at -18C in hermetically closed containers, the interval should be ten years for species expected to be long lived and five years or less for species expected to be short-lived.
- The viability threshold for regeneration or other management decision such as recollection should be 85 percent or lower depending on the species or specific accessions of initial viability.
For field genebanks, monitoring for quality should also cover infection by pests and diseases, adaptation to the site and encroachment of other accessions between plots, as well as viability of the material. It is suggested that monitoring should be weekly to observe any problems as they arise and take action to reduce risks. Additional monitoring should be done daily after new planting, pruning or cutting back and after events that could increase the risk such as heavy rain.
Monitoring for quantity of seeds or propagules is best done on a continuous basis and always before material is distributed in response to requests.
Viability monitoring in seed genebanks
Viability is monitored by conducting a germination test on a fixed sample or by sequential germination.
Fixed sample size germination test
For the fixed sample size germination test, it is recommended to use a minimum of 200 seeds (as two replicates of 100 seeds or four replicates of 50 seeds) if sufficient seeds are available. If the quantity is limited, 50-100 seeds can be tested in two replications. For information on seed germination methods see the section on viability testing.
Sequential germination tests
The sequential germination test uses fewer seeds per replicate than the standard germination test. As the name suggests, the germination test is done sequentially on replicates and stopped as soon as the results allow a decision to be made on whether regeneration is necessary. Otherwise, the methods and conditions for germination are the same as described for the fixed sample size germination test (see the section on viability testing).
The number of seeds required for each replicate may vary, but it is recommended to use at least 40 seeds per replicate. The first replicate of seeds is tested and the number of seeds that germinate are counted. If the number of seeds germinated is 29 or less, the accession requires regeneration. If more seeds germinate the test is repeated with another replicate of 40 seeds and the results of the two tests added. If less than 64 seeds germinate, the accession requires regeneration and if more than 75 seeds germinate regeneration is not necessary. The test can be repeated until a decision on regeneration can be made but no more than ten times.
Monitoring is a crucial activity in genebank management as it helps to provide information on seed stocks that are becoming low, accessions that need viability testing and those that require regeneration. Without proper documentation of the data from preceding genebank activities, effective monitoring is difficult to carry out.
References and further reading
Engelmann F, Engels JMM. 2001. Technologies and strategies for ex situ conservation. In: Engels JMM, Ramanatha Rao V, Brown AHD, Jackson MT, editors. Managing plant genetic diversity. CABI, UK. 512p.
Engels JMM, Visser L, editors. 2003. A guide to effective management of germplasm collections. IPGRI Handbooks for Genebanks No. 6. IPGRI, Rome, Italy. Available in English (1.4 MB) and Spanish (1.5 MB).
FAO. 2013. Genebank standards for plant genetic resources for food and agriculture. Food and Agriculture Organization of the United Nations, Rome. Available in English, Spanish, French, Arabic, Russian and Chinese here.