CGN forage crops collection

The accessions from the grasses originate from the collection of the former Foundation of Agricultural Plant Breeding (SvP), from Dutch private breeding firms and from the collections of Plant Variety Research (Van Soest and Boukema, 1995). Most of the clover accessions were collected by CGN in the Netherlands (Van Soest and Dijkstra 1986, 1998). During collecting missions in Uzbekistan and Kyrgyzstan some 30 clover accessions were collected (Van Soest 1998).

Composition

Grasses

The CGN grasses collection consists predominantly of economically important forage grasses that are cultivated in Northwest Europe. The Lolium collection, including accessions of perennial and Italian ryegrass, forms 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 was carried out, aiming to analyse the variation present in populations occurring in old Dutch grasslands, in nature reserves, and in cultivars (Van Treuren et al. 2005). This study indicated that basically the same range of genetic variation is covered by the groups. From this study it could be concluded 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 (Trifolium repens) which was also analysed in this study.

There are also a number of smaller collections. The Phleum collection includes accessions of two species and the Festuca collection holds accessions of three species. Then there are collections of Dactylus glomerata, Poa pratensis and Agrostis cappilaris. The Poa collection is based on old and modern Dutch cultivars and accessions that were collected in 2005 by CGN in old Dutch grasslands (Van Treuren 2008).

Clover

The CGN clover collection consists of white clover (Trifolium repens) and red clover (Trifolium pratense) accessions. The red clover accessions were mainly obtained during collecting missions in the Netherlands (Van Soest and Dijkstra 1986, 1998). Besides the collected ecotypes, the collection consists of accessions of landraces, cultivars and tetraploid breeding lines. In the group of old landraces there are four old Dutch landraces: Groninger, Roosendaalse and Gendringse clover and Rode Maasklaver. Also for white clover collecting was done in the Netherlands in old grasslands. During these missions in all Dutch provinces accessions of white clover were collected. The locations where material was collected are represented in the figure above. The white clover collection consists ecotypes, landraces and cultivars, amongst which a set of old cultivars from the period between 1924 and 1990. Next to the material from European origin there is a small number of accessions from Central Asian origin (Uzbekistan, Kyrgyzstan) in the collection, collected during missions.

Regeneration

For the regenerations of grass seed CGN works in cooperation with breeding companies. De companies do all the regenerations, as there are only a handful of accessions that need to be done per year. Grasses are biannual and concerning vernalisation and day-length the species differ from one another. Because of this there are different sowing moments. The grasses are sown and are grown in pots in the first year. After vernalisation, in the second year, the plants are placed in isolation fields (cross and wind pollinators) for seed production. The harvest of seeds is done in July/August. The apomictic species Poa pratensis can be regenerated without isolation.

Regeneration of clover is biannual and is done in isolation cages. During summer sowing is done and after germination the seedlings are repotted into small pots where the plants can develop. During winter the plants are vernalised in an unheated greenhouse. In April the plants are repotted in bigger containers where they can develop further and can start bolting. When bolting starts the plants are placed in an isolation cage, because clover is a cross pollinator. During flowering pollinating insects are introduced in the isolation. In July/August the dry seed heads can be harvested.