EFFECTS OF INTERFERENCE BETWEEN PLOTS ON PERFORMANCE IN SUGAR-BEET VARIETY TRIALS - REASONS, IMPORTANCE AND APPROACHES FOR LIMITING THE EFFECTS

In a field trial at Gotttingen in the years 1995-1997 neighbourhood ef fects between sugar beet varieties were examined. Harvest of single ro ws showed signifikant influence of competition on the yield performanc e of two varieties with different competitiveness. The root yield of a variety with high competitiveness neighboured by a variety with low c ompetitiveness was 6% (1995) or 8% (1997) respectively higher than in pure stand. In contrast the low competitive variety showed higher yiel d in pure stand. There was only a week influence on juice quality. The neighbourhood effects seems to be connected with competition for ligh t, because the varieties with high competitiveness had a big leaf appa ratus and 10 cm higher stand height. An approach is outlined for limit ing the effects of interference by drilling of six-row plots and disca rding the outside rows where inter-cultivar competition can occur.