20 BULLETIN 1396, U. S. DEPARTMENT OF AGRICULTURE 
The experiment in eliminating inferior strains by selfing was 
planned to test the practicability of increasing the yield without 
necessitating the making of first-generation crosses each year. The | 
results indicate that for such a demonstration it will be necessary to 
start with a much larger foundation stock or with two stocks main- 
tained separately. The time and labor involved are excessive and 
would appear necessary only as a concession to the reluctance of seed- | 
corn producers to utilize first-generation crosses. 
SUMMARY 
A series of experiments is reported that compares the “‘ear-to-row”’ | 
breeding method with a method of close breeding in which inferior | 
strains were eliminated through selfing and the surviving strains 
recombined. 
Sacaton June corn, a variety derived from Mexican June corn and 
adapted to the irrigated regions of the Southwest, was chosen for the 
experiments, which were made at Sacaton, Ariz. 
Twenty ears were selected as the foundation stock. The experi- 
ments were started in 1918 with two identical ear-to-row plantings 
from these ears. 
In the crossed experiment, crosses were made between the highest | 
yielding rows and hatwdan the highest yielding plants regardless of 
row. In the selfed experiment, plants in each row were selfed, and 
selections for the following season were made from the highest yield- 
ing rows and the highest yielding individual plants. 
Following three years of selfing, crosses were made between the 
selfed strains with the idea of reestablishing the vigor of the stock, 
the undesirable lines having been eliminated. 
Numerous abnormalities were observed in the course of the experi- 
ments. Few of these appeared to be definitely associated with 
decreased yield, but in the selfed experiment there was a close nega- 
tive correlation between yield of the strain and the number of abnor- 
malities observed. There is thus reason for believing that the 
elimination of the numerous minor abnormalities common in most 
varieties of maize will increase the yield. 
The selection of selfed lines was effective in establishing high-yield- 
ing strains. Some of the selfed strains gave yields above the aver- 
age of the crossed experiment in 1923 and 1924. There was a signifi- 
cant parent-offspring correlation, high-yielding progenies producing 
high-yielding progenies the following season. In the selfed experi- 
ment, selections from high-yielding progenies greatly outyielded selec- 
tions from individual high-yielding plants chosen without regard to 
progeny performance. 
In the crossed experiment, there was no significant difference in 
the yields of selections from high-yielding progenies and individual 
high-yielding plants. 
n 1923 a comparison of the results of the two breeding methods 
was made by planting alternate rows to a mixed sample of hand- 
pollinated seed from the crossed experiment and a mixture of F, prog- 
enies from crosses between selfed progenies. The crossed experiment. 
outyielded the selfed experiment by about 25 per cent. The differ-— 
ence is undoubtedly significant, being seven times the probable error. - 
In 1924 a more comprehensive yield test was made, involving the- 
continuously crossbred seed from the crossed experiment, crosses _ 
i 
