Overview of Heterosis and Heterotic Groups in Agronomic Crops
- Albrecht E. Melchinger and
- Ramesh K. Gumber
Heterotic groups and patterns are of fundamental importance in hybrid breeding. We start with definitions of these tenns. Theoretical and experimental arguments are given demonstrating the superiority of inter-group compared with intra-group crosses under two aspects: (i) a higher mean heterosis and hybrid perfonnance and (ii) a reduced specific combining ability (SCA) variance and lower ratio of SCA to general combining ability (GCA) variance, which implies that identification of superior hybrids can be based mainlyon testing for GCA. We review the degree of heterosis, history and current status of hybrid breeding, and development of heterotic groups in five major crops with different pollination systems: allogamous—maize (Zea mays L.) and rye (Secale cereale L.); partially allogamous—faba bean (Vicia faba L.) and oilseed rape (Brassica napus L.); autogamous— rice (Oryza sativa L.). Fundamental principles and systematic approaches for identification of heterotic groups and patterns and enlarging their genetic base are suggested with special consideration of the use of molecular markers for grouping of gennplasm. Adapted populations, isolated either by time and/or space are most suitable candidates for promising heterotic patterns. The potential of heterotic groups in clone and population breeding also is discussed.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 1998. . Copyright © 1998 by the Crop Science Society of America, Inc., 5585 Guilford Rd., Madison, WI 53711 USA