DENSITY AND REDUCTION OF THE STAND AT ALFALFA VARIETIES (MEDICAGO SATIVA L.)

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/m(2). 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).