The CGN forages collection consists at present of 966 accessions of 13 different species: 11 grass species with 703 accessions and two clover species with 263 accessions.
The grass species were received from the former Foundation of Agricultural Plant Breeding (SvP), private breeding firms from The Netherlands (van Soest and Boukema, 1995) and from the collections of Plant Variety Research Most of the clover accessions were collected by CGN in the Netherlands from 1985 to 1986 (van Soest and Dijkstra, 1986; van Soest and Dijkstra, 1998). The accessions of T. repens were collected in all provinces of the Netherlands. Exploration missions were organised to Uzbekistan (1997, 1999) and Kyrgizstan (1999). During these missions around 60 forage accessions were collected (van Soest, 1998).
The CGN grasses collection consists predominantly of economical important forage grasses cultivated in N.W. Europe. The Lolium collection, including accessions of perennial and Italian ryegrass, forms with 394 accessions the most important collection. This collection includes besides modern cultivars also old cultivars and ecotypes collected in old Dutch pastures.
A study on Lolium perenne carried out by van Treuren et al (2005) aiming at the analysis of variation present in populations occurring in old Dutch grasslands with grasslands, in nature reserves and in cultivars using AFLP markers and morphological traits indicated that basically the same range of genetic variation is covered by the three groups, although the reference varieties analysed harboured lesser variation. Therefore it was concluded by van Treuren et al (2005) that no specific conservation measures are currently needed to maintain genetic diversity of perennial ryegrass occurring in old Dutch grasslands (the same conclusion could be drawn for white clover as this species was also analysed in this study).
Next to the large Lolium collection there are also a number of smaller collections. The Phleum collection includes two species and consists of 105 accessions, the Festuca collection consists of 71 cultivars of F. rubra, in the Dactylus glomerata collection 42 accessions are present and the Poa pratensis collection is based upon 78 old and modern Dutch cultivars. Furthermore there is a small Agrostis cappilaris collection which consists of 11 Dutch cultivars. The Poa collection will be further enlarged as accessions collected from old Dutch grasslands will be added to this collection (van Treuren, 2008).
The CGN clover collection consists of 165 white clover (T. repens) and 98 red clover (T. pratensis) accessions. The red clovers were mainly obtained during collecting missions in the Netherlands carried out in 1985 and 1986 (van Soest and Dijkstra, 1986; van Soest and Dijkstra, 1998). The collecting sites in all provinces of the Netherlands are presented in Figure 2. Besides the collected ecotypes (139 accessions), the collection consists of 26 accessions of landraces, cultivars and tetraploid breeding lines. Under the group of old landraces there are four old Dutch landraces: Fries-Groninger-, Roosendaalse- and Gendringse red clover and Rode Maasklaver.
In 1997 and 1998 collecting trips were organised to all provinces in the Netherlands and some 50 accessions of white clover were collected in old Dutch grasslands. Currently the white clover collection consists of 68 ecotypes and landraces and 28 cultivars amongst which 21 old cultivars from the period between 1924 and 1990.
Next to the clover material from European origin there are around 50 accessions from Central Asian origin (Uzbekistan, Kyrgizstan) collected during 1998 and 1999.
Previously all forage crops were regenerated in specially isolated plots in rye fields. Since 1999 Triticale has been used as isolating crop. Only material of Poa pratensis is not regenerated in isolation plots. The distance between the plots is approximately 50 m. Material that needs vernalisation is kept in unheated greenhouses during the winter. After sowing the seeds in the summer, some 50 plants are planted in April of the following year in the isolation plots. To prevent lodging, some grass species are staked. Harvest of the seeds is carried out in July/August.
Soest, L. J. M. van, K. I. Baimatov & V. F. Chapurin, 1998. Multicrop collecting mission to Uzbekistan. Plant Genetic Resources Newsletter 116: 32-35.
Soest, L. J. M. van en I. W. Boukema (eds), 1995. Diversiteit in de Nederlandse Genenbank [Diversity in the genebank of The Netherlands] CPRO/CGN, Wageningen, The Netherlands. 126 p.
Soest, L. J. M. van & H. Dijkstra, 1986. Red clover collecting in The Netherlands. Internal report CGN/SVP. Wageningen, The Netherlands, 3 p.
Soest, L. J. M. van and H. Dijkstra, 1998. Current status of CGN forages collection. In: Maggioni, L. et al. 1998. Report of a working group on Forages. Sixth meeting, 6-8 March 1997, Beitostølen, Norway. IPGRI, Italy: 78-80.
Treuren, R. van, 2008. AFLP fingerprinting of Kentucky bluegrass (Poa pratensis L.) from undisturbed Dutch grasslands: implications for conservation. Plant Genetic Resources Newsletter, 153: 1-8.
Treuren, R. van, N. Bas, P. Goossens, H. Jansen & L.J.M. van Soest, 2005. Genetic diversity in perennial ryegrass and white clover among old Dutch grasslands as compared to cultivars and nature reserves. Molecular Ecology, 14: 39-52.