F. Keeble and C. Pellew, “The mode of inheritance of stature and time of flowering in peas (Pisum sativum),” Journal of Genetics 1, 1 (November 1910): 47-56.
Note: This paper demonstrated a mendelian basis for hybrid vigor. It was one of the bases for Donald F. Jones’s theory of hybrid vigor.
DOI: https://doi.org/10.1007/BF02981568
George H. Shull, “The composition of a field of maize,” Journal of Heredity os-4, 1 (1908): 296-301 and Report of the American Breeders’ Association, 4 (1908): 296-301.
Note: This paper showed that ordinary field-pollinated corn is typically very varied genetically. Pollinating corn plants with their own pollen (inbreeding) resulted in genetically monotonous and unhealthy plants. But when two such lines were combined, the offspring were often healthy and robust. Shull argued that corn-breeders should not try to assemble all their desired characteristics in one strain — rather, the better strategy was to look for the optimal combination of two inbred strains.
DOI: https://doi.org/10.1093/jhered/os-4.1.296
George H. Shull, “A pure line method in corn breeding,” Journal of Heredity os-5, 1 (1909): 51-58.
Note: In this paper, Shull described a way to put his discovery into practice in the field and combine two inbred strains of corn into a hybrid strain.
DOI: https://doi.org/10.1093/jhered/os-5.1.51
George H. Shull, “Duplicate genes for capsule-form in Bursa bursa-pastoris,” in Zeitschrift für induktive Abstammungs- und Vererbungslehre 12, 1 (1914): 97-149.
Note: In this paper, Shull coined the term ‘heterosis’ for hybrid vigor (p. 127). The context for his coinage of this term was a theory of hybrid vigor that many in the first decades of the twentieth century — including Shull himself — found persuasive at that time. The theory was that the very fact of having heterogenous genetic material itself had a stimulating effect on an organism, and that this played a role in hybrid vigor. That is, if there was a gene with two alleles, A and a, an organism with an Aa genotype would be more vigorous than one with an AA or aa genotype, regardless of what the gene actually did. What this stimulating effect involved was unclear, and the theory ultimately disappeared because scientists found other theories, like that of Jones, more productive of questions they could address. Shull originally described “heterosis” as this “stimulation” that he and others observed in hybridized plants. The theories behind heterosis changed — and continue to develop — but the term itself remains.
DOI: https://doi.org/10.1007/BF01837282
Donald F. Jones, “The effects of inbreeding and crossbreeding upon development,” Connecticut Agricultural Experiment Station Bulletin 207 (September, 1918).
Note: In this publication, Jones presented a theoretical basis for hybrid vigor, based on mendelian genetics and the concept of linkage. He cited the work of Shull, East, Hayes and others. He also (p. 60) briefly described the double cross method of growing hybrid corn.
Available through archive.org
Donald F. Jones and Paul Mangelsdorf, “Crossed corn,” Connecticut Agricultural Experiment Station Bulletin 273 (January, 1926).
Note: Jones and Mangelsdorf provided a practical explanation of hybrid corn in the context of agriculture and agricultural science.
Available through archive.org
W. Ralph Singleton, “Hybrid vigor and its utilization in sweet corn breeding,” The American Naturalist 75, 756 (1941): 48-60.
Note: This was the published form of the talk on the history of hybrid corn that Singleton gave at a genetics conference in Edinburgh in 1939. In the course of his research for the paper, Singleton began a long correspondence with Shull.
JSTOR, https://www.jstor.org/stable/2457253