Hayes and Garber - Cucurbit Breeding

CHAPTER IX
SOME RESULTS OF SELECTION WITH SELF-
FERTILIZED CROPS
In its broadest sense, selection is really at the basis of all animal
or plant improvement by breeding. Evidence accumulated by
early plant breeders indicated to them that selection of the most
desirable plants for seed was highly profitable, irrespective of
whether the plants were naturally cross-fertilized or self-fertilized.
Darwin believed that the mean type of any population
could be changed by a plus or minus selection. It was left for
Johannsen (1903) to point out the true significance of selection
within a naturally self-fertilized crop.
Before discussing Johannsen 's pure-line concept and its relation
to the improvement of self-fertilized crops by selection, a
brief survey of early work on improvement of naturally selffertilized
cereals is desirable. .
EARLY INVESTIGATORS IN SELECTION OF SELF-FERTILIZED
CEREALS
John Le Couteur and Patrick Shirreff were first to use the progeny
test in making selections. The former did considerable
work with wheat. In the early part of the nineteenth century
he grew what he supposed to be a uniform variety. Professor
La Gasca, of the University of Madrid, upon inspecting Le Couteur
'& wheat in the field pointed out no less than 23 distinct
forms. This observation led the latter to make a collection of
150 varieties. Le Couteur simply took it for granted that the
progeny of any one individual would breed true. Patrick
Shirreff, another breeder of cereals, who lived in the middle of the
nineteenth century, worked along somewhat different lines. He
searched for the exceptional plant to start a new variety, and
discovered seven such varieties.
Frederic F. Hallett also followed rigid selection of individual
plants in his wheat breeding. Furthermore, he proceeded on the
theory that the selection of the best spike on the plant and the
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