Natalia GEORGIEVA, Ivelina NIKOLOVA
Abstract: With purpose to study the density and reduction of stand at 9 alfalfa varieties (Europe, Prista 2, Prista 3, Prista 4, Obnova 10, Pleven 6, Dara, Multifoliate and Dama)during 2006–2009 period in IFC–Pleven is carried out an experimental activity. The average density of stand at studied alfalfa varieties during the first year of development was 1313 plants/m2. The reduction during next three years was disproportionately and was the strongest pronounced during the second year–by 58.3% to the density of the stand in the previous year. During the third experimental year the reduction of alfalfa was still strong pronounced albeit with a lower value (51.1%) and during the fourth year it was 5 times less than that during the previous two years at average value of 10.6%. In the end of four–year experimental period the reduction at different varieties was in limits from 68.6% (Obnova10) to 85.7% (Dara) at average value for the species of 81.8%. It is established correlations with high negative value among the stand density and root mass weigh/plant (r=–0.811) and diameter of root collar (r=–0.692), and a correlation with medium negative value between the stand density and number of stems/plant (r=–0.488).
Key words: alfalfa, varieties, stands density, reduction