Self-seeding of subterranean clover in degraded birdsfoot trefoil seed production stands.

In connection with the dilution of seed production birdsfoot trefoil stands the possibility of under-sowing them with selfseeding crops was studied. The trial was carried out on the experimental field of Institute of Forage Crops, Pleven, Bulgaria with birdsfoot trefoil (Lotus corniculatus L.) Targovishte 1 variety. In autumn after the fourth year of use of the stands (for seed production direction) an under-sowing with three subterranean clover subspecies was done as follows: Trifolium subterraneum ssp. brachycalicinum (Antas variety), Trifolium subterraneum ssp. yaninicum (Trikkala variety) and Trifolium subterraneum ssp. subterraneum (Denmark variety). The capacity of self-sowing of subterranean clover in birdsfoot trefoil stands was assessed. It was found that subterranean clover effectively used the autumn-winter soil moisture, formed a sufficient number of seeds for self-seeding and germinated plants occupied the sites of the dropped birdsfoot trefoil plants. Trifolium subterraneum ssp. brachycalicinum showed the best self-seeding ability. Thus, after under-sowing with subterranean clover, degraded seed production birdsfoot trefoil stands could be used for forage.