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 Göttingen in the years 1995-1997 neighbourhood effects between sugar beet varieties were examined. Harvest of single rows showed signifikant influence of competition on the yield performance of two varieties with different competitiveness. The root yield of a variety with high competitiveness neighboured by a variety with low competitiveness was 6% (1995) or 8% (1997) respectively higher than in pure stand. In contrast the low competitive variety showed higher yield in pure stand. There was only a week influence on juice quality. The neighbourhood effects seems to be connected with competition for light, because the varieties with high competitiveness had a big leaf apparatus and 10 cm higher stand height. An approach is outlined for limiting the effects of interference by drilling of six-row plots and discarding the outside rows where inter-cultivar competition can occur.