Seeds and debris are separated using differences in seed size, specific gravity and floating speed by passing the sample through a combination of different sieves (round or slit sieves) and air flow devices. Dried samples are threshed using a small winnowing machine (Clipper). Seed cleaningĪfter harvesting, the bagged and labelled samples are preliminary dried in an oasthouse and later in a climate chamber at 15☌ and 30% RH. If the germination percentage does not meet the criteria, the sample needs to be regenerated again. because of climatic constraints, acceptable levels of germination percentages may be lower. If material is difficult to regenerate, e.g. In general the germination percentage should be at least 80% for varieties and landraces and 60% for wild species if samples are to be included in the collection. The germination tests are executed by CGN. The tests are in compliance with the ISTA rules, which describe standard tests per crop. In the case of some wild species smaller seed samples are tested. Random samples of usually about 200 seeds are tested. Sample viability is determined in germination tests. Criteria for purity are: absence of dust particles and broken or empty seeds. The purity of the sample is checked visually and if necessary the sample is cleaned. The upper limit is usually the quantity of seeds that can be stored in the largest pre-fabricated sample bags (volume ±500 cm3).
A sample must contain a minimum amount of seeds, this differs per crop.
When seed samples enter the storage facilities, the seed quantity will first be determined. Sample quantity and quality and viability
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