Since 1996, VDLUFA’s seed testing lab group IV has initiated and evaluated 15 method performance studies and 34 comparative ring tests. In total, 269 samples from different crop groups were sent to the participating laboratories. In addition to the German VDLUFA members, laboratories from Austria, Switzerland and Czech Republic systematically participated in these comparative ring tests. Within the framework of ISTA method development, ISTA stations from all over the world have also been involved.
Species, parameters to be tested and a ring test leader are determined during the annual fall meeting by the lab group members. The ring test leader carries the responsibility for sample preparation, sample shipment, statistical evaluation and interpretation of the results. The software for calculation of the results and graphic representation is to be found on web page of the seed lab group, internal part. The algorithm based on Tattersfield (1979) is published in Seed Science and Technology 7, (2), 247-257. The discussion of the results takes place during the annual spring meeting mostly in combination with a workshop.
The aim of the lab group is to organize two comparative ring tests per year at minimum. In addition to the methods relevant to ISTA, these tests also include current issues involved within the testing for the official seed certification and the official seed control.