ABSTRACT
In the breeder’s perspective, plant and crop physiology were often seen as disciplines that served to explain change after the fact rather than to generate change. While crop physiology is acknowledged for having been able to explain yield modifications brought about by breeding (e.g., see chapter on “Wheat and Barley”), it was often blamed for not being effective enough in bringing about yield increases. For example, the contribution of the dwarfing genes to cereal yield improvement was well explained by an increase in harvest index and by faster and timely assimilate partitioning with hardly any increase in photosynthesis and total biomass production. Crop physiology had little to do with the progress made in breeding by using these genes. In fact, plant breeders and physiologists did not even realize initially that height genes had any value in this respect besides an expected improvement in lodging resist-ance. However, the ensuing physiological studies of the function of these genes did have an impact on the continuing breeding efforts. Plant physiology research outlined the pros and cons of the dwarfing genes in terms of adap-tation to different environments, which helped breeders develop a strategy of deployment of these genes in different target environments. The ensuing studies of gibberellic acid responsiveness of the height genes led to the development of a phenotypic screening method for these genes at the seedling stage.
