NordGen's red clover collection carries properties important for the development of persistent forage legumes

2021.04.22

In the Arctic Clover project, wild populations and landraces from NordGen's collection of red clover have been compared with commercial varieties. A new scientific article shows that the genebank material carries important properties that can be used to produce better red clover varieties, not least when it comes to the winter survival of the fodder plant.

Commercial cultivation of crops such as cereals or vegetables requires soil with a good quality. The cold climate and the short growing season also contribute to large parts of the agricultural area in the Nordic countries instead being occupied by grasslands or natural pastures for animal husbandry. – Red clover is the most important forage legume in the Nordic countries, but today there are restrictions on how the fodder plant can be used, partly due to problems linked to its persistency. When sowing, red clover is combined with different grass species but the commercial clover varieties have a tendency to cope with the winters poorly and disappear from the grass after a while, says Anna Palmé, one of NordGen's plant experts and co-author of the article. This is one of the reasons why NordGen's working group for grass plants initiated the Arctic Clover project in 2014. Results from the now completed project were recently presented in an

48 wild varieties and landraces of red clover from NordGen's collection were selected since their geographical origin in the Nordic countries. The genebank material was evaluated and traits of the accessions were compared with six commercial red clover varieties from the processing companies Lantmännen, Graminor and Boreal.

Evaluation experiments in four countries

In 2015 and 2016, evaluation field trials were conducted at four locations in Norway, Sweden, Finland and Iceland. In Norway, a controlled cultivation experiment was also carried out in greenhouses where so-called LT50 tests were made to study at what temperature 50 percent of the plants died. The experiments showed, among other things, that a majority of the accessions from NordGen performed better than the commercial varieties in terms of winter survival and tolerance to cold. Therefore, landraces and the wild varieties can constitute an important genetic resource in future breeding work. – There is important variation in the genebank which is very interesting for breeding purposes, for example when it comes to winter survival. But there is also variation in terms of yield and flowering, important for the seed production, says Palmé. An increased use of red clover as feed in the Nordic countries can provide several environmental benefits. Grass does not fix nitrogen, but legumes such as red clover can. - Growing more red clover is also a step in the right direction to reduce dependence on imported protein feed. A combination of, for example, locally grown peas, broad beans and red clover can help reduce soy imports, says Palmé.

Valuable information for plant breeders

Linda Öhlund works with forage plant breeding at Swedish Lantmännen and is also a co-author of the article. – The information from this type of study is very valuable to us in plant breeding. Red clover as a species is usually strongly adapted to its cultivation site and in this study we succeeded in jointly evaluating a significant number of accessions of red clover from NordGen in several places around the Nordic countries. Through the study, we were able to identify several accessions that had interesting properties that we would like to use for further processing activities, says Öhlund.

Continued research

She is also involved in several further studies concerning red clover, which is funded by SLU Grogrund. In the project "Resistance breeding for healthy crops", work is being done on several species. The work with red clover will be led by Christina Dixelius at SLU Ultuna. Here, the red clover's most important diseases, root rot and clover rot, will be studied in detail. Another project is entitled "Genomic selection in red clover (Trifolium pratense L)" and is led by Mulatu Gelata Dida at SLU Alnarp. - In that project, we will evaluate the cultivation value and other characteristics for a large number of varieties, breeding lines and semi-wild and other populations from NordGen. The evaluation is conducted, among other things, in field trials around the country, says Öhlund.

FACTS

Grasslands that are sown regularly cover 48 percent of the agricultural area in Norway. In Sweden the corresponding percentage is 40 and in Finland 28. In Iceland, most of the agricultural land is grassland but mostly natural pasture. The project's field trials on red clover were carried out in Jokioinen (Finland), Korpa (Iceland), Løken (Norway) and Lännäs (Sweden). In NordGen's collection, there are a total of about 500 accessions of red clover.