NODULATION AND ROOT ESTABLISHMENT OF TWO CLOVER SPECIES GROWN IN PASTURE MIXTURE WITH WHEATGRASS
A field trial was conducted during 2007-2010 at the Institute of Forage Crops, Pleven, Bulgaria to study the nodulation of subterranean clover (Trifolium subterraneum L.) and white clover (Trifolium repens L.) in some pasture mixtures using wheatgrass (Agropyron cristatum L.) as grass component. The treatments tested were: Subterranean clover (100%), White clover (100%), Subterranean clover + Wheatgrass (50%:50%), White clover + Wheatgrass (50%:50%), Subterranean clover + White clover (50%:50%), Subterranean clover + White clover + Wheatgrass (25%:25%:50%). It was found that subterranean clover in a mixture with wheatgrass formed 11.9% more nodules and by 11.0% higher root dry mass than in pure sward. White clover nodulated better in pure sward as compared to mixture and subterranean clover showed better nodulation than the white clover. The results obtained in the present study also indicated that wheatgrass in a mixture with white clover inhibited the root dry mass production by 22.2%. In the triple mixture (wheatgrass, subterranean clover and white clover) no significant differences were observed in characteristics of nodulation and dry mass production.