Did Mendelism Transform Plant Breeding? Genetic Theory and Breeding Practice, 1900–1945

Abstract

Geneticists and plant breeders have occasionally made far-reaching claims for the importance of Mendelian theory in “revolutionising” plant breeding after 1900. While it is quite difficult to establish just how much impact Mendelism made upon breeders’ actual practice over the period in question, the aim of this chapter is to use published sources in order to assess the extent to which the theory might in principle have altered breeding practice. My conclusions are three. First, that none of the bold and general claims made for Mendelism’s revolutionary impact, especially before the First World War, were justified and are thus best seen as rhetoric designed to attract recruits and resources to an emerging field. Second, even if one focuses upon more restricted claims derived from the theory, several of these do not stand up to scrutiny. Finally, however, I examine the theory’s role in explaining the breeding process, noting how some of its features—e.g., dominance/recessiveness, the organism as an aggregate of traits—may well have altered the breeders’ perceptions of possibility, enabling them to analyse the efficacy of existing methods and to make incremental improvements to some methods (rather than developing radically new ones).