Alternative approaches and perspectives in breeding for higher yields

Abstract

This paper considers strategies for increasing commercial yields of crops by plant breeding, both directly by increasing yield potential, and indirectly by improving the expression of yield potential in practice. Before Donald's discussion of 'ideotype' approaches to yield improvement, little attention was given to crop improvement by considering morphological or physiological traits which could directly contribute to higher yields. Whilst his ideotype approach has generated considerable interest, there has been limited adoption of ideotypes in breeding programmes, and limited success in terms of yield improvement. This is discussed in relation to conceptual and practical difficulties in the implementation of ideotype breeding, including the difficulty of identifying yield-enhancing traits, and the lack of genetic diversity for such traits in some agricultural crops. Alternative strategies for yield improvement include using techniques such as heterosis in F1 hybrids, and the identification and manipulation of individual 'yield' genes (particularly using the recombinant DNA technology of restriction fragment length polymorphisms (RFLP). However, an emphasis on the 'defect elimination' approach to plant improvement will continue to be relevant, as many Australian farm crops yield well below their genetic potential. Substantial progress is likely to be made by addressing the control of air- and soil-borne pathogens (including take-all), mineral deficiencies and toxicities, appropriate phenology, and resistance to frost damage during heading in cereals. © 1991.