A SYSTEM FOR BREEDING CORN 
OR GREGARIOUS ANIMALS 
A. N. HuME 
South Dakota State College and Experiment Station 
URING the past three years, the 
|e writer has attempted to con- 
duct a corn breeding system 
that should accomplish the three 
following requirements : 
(1) Insure continuous  ear-to-row 
selection for high yield by using ears 
or remnants from tested rows. 
(2) Insure direct cross-pollenation 
between high yielding strains, thus 
avoiding the usual ill effects of 
in-breeding; with the use of a single 
ear in each quarter of the plot for all 
sire rows and detasseling all even- 
numbered rows. 
(3) Annual introductions of strains 
from outside sources, through the even- 
numbered detasseled rows of the breed- 
ing plot. 
The first of these attempted require- 
ments is based upon the assumption 
that some sort of selection is bound to 
be the basis of progress in corn-breed- 
ing. The second is intended to recog- 
nize the principle that it is usually 
desirable to secure the crossing of 
strains that have previously been inbred 
or at least closely bred. (Hybridiza- 
tion Methods in Corn Breeding. Shull 
—American Breeders Magazine, April- 
June, 1910.) The third feature namely, 
the introduction of outside strains, 
conforms to the idea that “selection 
is a sieve,” or at least it may be. There 
can hardly be a practical reason why a 
corn breeder should start with a given 
number of mother ears, say ninety-six, 
and assume that all determinants of 
high yield are included within the 
number originally selected. 
Furthermore, the plan of introduc- 
ing ears from outside the breeding plot 
into the even-numbered  detasseled 
rows gives opportunity for testing the 
yielding power of such introductions 
before permitting them to mature pol- 
len, and consequently makes it possible 
to discard them entirely if they are 
found unworthy, without contaminat- 
ing the other “blood lines” of the 
breeding plot. This idea conforms to 
the earlier suggestion of Williams of 
Ohio. The plan, or combination of 
plans employed here is described con- 
cretely in the South Dakota Experi- 
ment Station Bulletin No. 186. 
The writer would suggest that this 
idea of making introductions into corn 
breeding plots through the “dam lines” 
ought to be extended. The chief rea- 
son for adhering to the plan of dividing 
the breeding plot into four squares of 
twenty-four rows each (adapted from 
Illinois Experiment Station Bulletin No. 
100) is to secure a greater number of 
relatively short rows and a relatively 
large number of introductions into these 
“dam rows,” and also to enable one 
to plant all “sire-rows” in each quarter 
with a single ear. 
It is arbitrary enough to make four 
quarters of a corn-breeding plot with 
all odd-numbered rows in each quarter 
planted from a single high-yielding ear, 
and with all the twelve even-numbered 
rows detasseled, with three new intro- 
ductions among the twelve each year. 
It works out conveniently. 
The essentials of the plan of this 
corn breeding plot might be adopted by 
poultry breeders, who have a sufficient 
number of birds to divide into four 
pens, each with its quota of hens and 
one male bird. The rule would be, 
that all birds in all four pens should 
be leg-banded and the hens faithfully 
trap-nested and their egg records kept. 
At the beginning of any given sea- 
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