CORN BREEDING 
53 
entering it. Entries for the three districts of a section are known 
as " section entries," and the average productiveness of these entries 
on the three farms in the section is reported separately. The yields 
of the 10 leading section entries in the south-central section in 1924 
and 1925, as published in the Annual Keports of the Iowa Yield 
Test (i, 66), are given in Table 12. 
Table 12. — Yields of the 10 leading entries in the south-central section of the 
Iowa corn-yield test in 1924 and 1925 
[Adapted from Iowa investigators {1,66)) 
1924 
1925 
Kank 
Designation 
Acre 
yield 
(bushels) 
Rank 
Designation 
Acre 
yield 
(bushels) 
1 
Fi Hybrids J 
51.33 
45.11 
41.18 
40.30 
40.21 
39.10 
38.80 
38.34 
38.16 
38.00 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
Hybrid B > . 
77.13 
2 
Ioleaming 2 
77.05 
3 
Hybrid C » 
73.81 
4 
Learning X White Pearl » 
Bloody ButcberXWhite Pearl L 
Black's Reid 
Hybrid \ K. 
70.94 
5 
Reid... 
69.81 
6 
Black's Reid 
69.57 
7 
69.07 
8 
3 
68.33 
9 
3 
68.07 
10 
Reid 
3 
67.60 
1 Crosses between selfed lines. 
2 Cross between two strains of Learning. 
3 Information is not reported, as entries ranked below the top third. 
The first five ranking entries in 1924 and the first four ranking 
entries in 1925 were crosses. One cross in each year was between 
open-fertilized strains, and the others were between selfed lines. 
With the exception of the entry ranking first in 1924, which was 
entered by the Bureau of Plant Industry, all of the crosses were 
entered by private individuals. Of most interest, however, are the 
outstanding yields of the best crosses above those of the best com- 
mercial varieties, the superiority being 31.3 per cent in 1924 and 10.5 
per cent in 1925. 
Summarizing the preceding data, it may be said that (1) in all of 
the experiments some cross or crosses have been significantly higher 
yielding than the best commercial varieties available for the sections 
where the comparisons have been made; (2) the increases obtained 
from the .more productive crosses have been large, many of them 
being 30 per cent or more; (3) when the same crosses have been 
compared over a series of years, the results from season to season 
have been consistent enough to show that the larger yields from the 
crosses could be expected to follow with reasonable assurance; and 
(4) consistency also is shown by the performance of several crosses 
of similar parental constitution. 
PLACE OF SELECTION WITHIN SELFED LINES 
The methods of reproduction and inheritance in corn which were 
considered in the first part of this bulletin show clearly that con- 
trolled pollination is the only basis for definite corn breeding. They 
also suggest a period of self-fertilization as the desirable initial step 
in such a program, in order that lines breeding true for various 
