The paper deals with the transformation of plant breeding from an agricultural practice into an applied academic science in the late 19th and early 20th centuries Germany. The aim is to contribute to the ongoing debate about the relationship between science and technology. After a brief discussion of this debate the first part of the paper examines how pioneers of plant breeding developed their breeding methods and commercially successful varieties. The focus here is on the role of scientific concepts and (...) theories in the agricultural innovation process. The second part turns towards the strategies by which agronomists tried to establish plant breeding as an academic discipline and themselves as the new experts for breeding research and varietal development. Again, the focus is on the interplay of scientific theory and agricultural practice. It is argued that in order to better understand the transformation of plant breeding into an applied academic science we have to take different levels into account, i.e. the levels of organizations, individuals and objects, at which science and technology interact. (shrink)

In addition to his experiments on selection in pure lines, Wilhelm Johannsen performed less well-known hybridisation experiments with beans. This article describes these experiments and discusses Johannsen’s motivations and interpretations, in the context of developments in early genetics. I will show that Johannsen first presented the hybridisation experiments as an additional control for his selection experiments. The latter were dedicated to investigating heredity with respect to debates concerning the significance of natural selection of continuous variation for evolution. In the course (...) of the establishment of a Mendelian research program after 1900, the study of heredity gained increasing independence from questions of evolution, and focused more on the modes and mechanisms of heredity. Further to their role as control experiments, Johannsen also saw his hybridisation experiments as contributing to the Mendelian program, by extending the scope of the principles of Mendelian inheritance to quantitative characters. Towards the end of the first decade of genetics, Johannsen revisited his experiments to illustrate the many–many relationship between genes and characters, at a time when that relationship appeared increasingly complex, and the unit-character concept, accordingly, became inadequate. For the philosophy of science, the example shows that experiments can have multiple roles in a research programme, and can be interpreted in the light of questions other than those that motivated the experiments in the first place. (shrink)