Selection for sugar yield in sugar beet, Beta vulgaris, using different selection indices

In sugar beet breeding, sugar yield is mainly influenced by root yield and sugar content. Ln this short communication several indices to select for bo th traits simultaneously are compared in order to find the best one. The in dices are correlated with the base index of Williams (1962) from independen t experiments. The indices differ in the amount of information necessary fo r the calculation of their weights. Three different series of each eight si tes gave similar results. The optimum index, using all information from phe notypic and genotypic variances and covariances, did not perform best. Suga r content with its higher heritability must have a larger weight than root yield. Heritabilities as index weights performed best, but two other indice s using heritabilities and phenotypic but no genetic covariances also perfo rmed well.