CGN lamb’s lettuce collection

History

CGN adopted a new policy in 2010 to specialise in vegetable crops which resulted in the development of several new crop collections. These new collections also included lamb’s lettuce, due to its relatively poor representation of genetic resources in existing collections and the importance of the crop to the Netherlands. Nowadays, the collection is one of the biggest lamb’s lettuce collections in the world.

Composition

Collection development started in 2011 with the acquisition of important Dutch varieties of cultivated lamb’s lettuce (Valerianella locusta). Some degree of overlap exists between CGN and the German collection since a selection of important Dutch varieties was obtained from the German genebank in Gatersleben. Subsequently, the collection was extended with cultivars and landraces originating from other European countries, in particular Germany and France, as far as the material was not yet properly conserved and distributed by other national gene banks.

In 2013, CGN started with sampling natural populations of V. locusta in the Netherlands, followed by collecting specimens of related species occurring in the Netherlands, including V. carinata, V. dentata and V. rimosa.

In 2024, CGN organised a collecting expedition together with INHORT, the Research Institute of Horticulture in Skierniewice, Poland. This expedition resulted in the addition of over 50 wild accessions from West and South Poland to the lamb’s lettuce collection.

Maintenance

Lamb’s lettuce accessions are regenerated in case of insufficient germination or depleted seed stocks. Lamb’s lettuce is sown in November and plants are overwintered under frost proof greenhouse conditions. Due to the selfing nature of lamb’s lettuce, regeneration can be carried out without specific protective measures to avoid pollination between accessions. A few meters distance is maintained between accessions to minimise the risk of contamination. Seed harvesting takes place in May or June.

Characterisation

Lamb’s lettuce accessions are described using the minimum descriptor list for Valerianella developed by the ECPGR Working Group on Leafy Vegetables. The minimum descriptor list for Valerianella and other leafy vegetables can be found at the ECPGR Leafy Vegetables webpage. The characterisation is further expanded upon using descriptors originating from the testing guidelines of UPOV.

Phenotypic data for cultivars that were described by the Netherlands Inspection Service for Horticulture (Naktuinbouw) are made available as downloadable files on CGN’s website. In 2019, the entire collection was grown in a field trial and described for various morphological traits. These data and pictures of the accessions are also available from CGN’s website.