For the first time, two Swiss bred cultivars of white clover appear on the seed market: Apis and Bombus. The pedigree of Apis traces back exclusively to ecotypes from Swiss natural grassland, collected in 1989; Bombus originates from plants of the variety Ladino which had resisted to competition by tall growing grasses in plot trials. By selecting a restricted number of cyanogenic individuals, the potential release of hydrocyanic acid was limited to the level tolerated for variety recommendation in Switzerland. This was necessary for Apis because the best ecotype populations were particularly rich in cyanogenic plants. For Bombus, we had to counteract the accumulation of cyanogenic plants which accompanied the selection of the most promising individuals. Both varieties belong to the group of large-leaved varieties. However, the leaves of Bombus are still markedly larger than those of Apis. As compared to the check variety Milo, they yield markedly more dry matter, particularly due to a more rapid departure of vegetation in spring and less winter damage caused by Sclerotinia. By utilizing the new varieties, it is possible to obtain the desired proportion of white clover in the sward with greater security.
Apis and Bombus, the first Swiss cultivars of white clover