Processing - cleaning and testing the seeds
1. Assessment of likely seed storage characteristics
2. Seed cleaning
3. Visual check on the quality of the collection
Careful visual studies of seeds in a collection reveal their morphology* and give a guide to their quality. A visual check cannot tell us that a seed might be capable of germination. However, it can give us an indication that the seed will not germinate. Following seed cleaning, we look for empty or incompletely-formed seeds and those that have been damaged by insects. Empty seeds and seeds where insects have damaged key parts of the seed embryo are ‘incompetent’ and will not germinate.
A longitudinal section through a seed of Ipomoea pauciflora
The checks are carried out on a small sub-sample of the main collection either by X-ray analysis or by means of a cut-test. If either method reveals a high proportion of ‘incompetent’ seeds then it may be possible to reduce the proportion by re-cleaning. If not, by recording the percentage of ‘incompetent’ seeds helps guide decisions following germination testing. For instance, if there are 50% incompetent seeds in a seed collection yet 50% germinate, we record germination as 100%, i.e. all of the competent seeds germinated. This makes sense when monitoring seed viability and when trying to understand seed physiology. It would make less sense in the commercial world where germination needs to reflect the status of the entire collection purchased.
*Morphology is the study of form and shape. In the case of seeds and fruit we look internally and externally. See a selection of images in this gallery.
