Nutritional considerations in attempts to change the chemical composition of crops.

Plant breeding and nutrition 3 protein wheat and barley and in the possibilities of manipulating amino acid composition have encouraged breeders to proceed more positively with biochemical problems. In many ways this resurgence has been due to the wide publicity given to the potential of the opaque-z gene in maize, and the high-lysine story has stimulated expectancies which I consider are rather rash in some cases. These developments have provided, we hope, a new dimension to crop breeding, and have brought together biochemists, nutritionists, geneticists and plant breeders in intimate association. New genes or genotypic associations are being feverishly sought after : world collections are being ransacked, and recourse to the exploitation of the newly available cytogenetic and breeding techniques has already started. We shall hear more of these matters in the papers to follow.