I. Nikolova, N. Georgieva

Abstract. During the period 2006-2009 in the experimental field of IFC-Pleven a field trial was conducted with 8 alfalfa varieties included in the Official variety list of Bulgaria (2005): Europe (France), Prista 2 (Obraztsov chiflik, Ruse), Prista 3 (Obraztsov chiflik, Ruse), Prista 4 (Obraztsov chiflik, Ruse), Obnova 10 (IFC, Pleven), Pleven 6 (IFC, Pleven), Dara (IFC, Pleven), Multifoliate (Obraztsov chiflik, Ruse). Most pronounced was the nodulation in varieties Europe, Obnova 10 and Multifoliate (average for the period 71.2, 66.8 and 65.1 pcs. of nodules/10 roots). Damaged nodules by larva of species of genus Sitona increased from spring to autumn regrowth in different years from 2.86% to 21.35%. As tolerant varieties to the damages of species of genus Sitona was manifested Obnova 10 and Multifoliate – the percentage of damaged nodules was average 6.83 and 7.93, the density of fretted fosses was 13.8 and 13.9 pcs. of fosses/10 roots, the percentage of damaged plants was 31.3 and 32.2%. The established varieties could be used as sources of germplasm which is tolerant to species of the genus Sitona.