The potential use of heterosis in Beta vulgaris L. II. Yield performance of pure lines and their hybrids

Summary The yield performance is described of pure lines obtained from doubled monoploids and their corresponding polycross and pair-cross hybrids. The total dry matter yields of fifteen pure lines averaged 60–90% of the yields of the progenitor and control varieties. Seven of the resultant polycross hybrids gave dry matter yields similar to or higher than the progenitor varieties, whilst the remaining hybrids were less productive than their parental lines. In pair-cross hybrids significant reciprocal differences were found in some cases. This was attributed to differences in self-fertility and the degree of self-fertilization in reciprocal crosses. Based on the frequency of offspring with white or coloured roots, self-fertilization frequencies ranging from 14% to 92% were found. It is estimated that in the event of complete cross-fertilization, the yields of certain pair-cross hybrids would have exceeded those of the control varieties by 9–29%.