ABSTRACT
Heritable traits controlled by one or multiple pairs of alleles are designated qualitative (Mendelian), or quantitative (additive) respectively. More than 40 recognized qualitative traits are listed in Table 2.1 (Smith, 1987); among them are annuality, monogermity, Mendelian male sterility, self-fertility and some forms of resistance to rhizomania (Lasa and Romacrosa, 1992). Sugar yield, processing quality, germination potential, bolting resistance, and most disease resistances are qualitative traits. Improving quantitative traits requires complex breeding schemes, compared to those used for qualitative traits.
