Corn Investigations 
105 
were outstanding in yield, averaging 79.4 bushels per acre in 
1907, as compared with 64.4 bushels for the original corn. 
A number of well-developed progeny ears grown from each 
of these four strains were shelled together into one composite 
sample for planting an isolation increase plat. This composite 
sample of four strains has ever since been continued in the same 
manner by merely selecting a large number of well-developed 
ears to be shelled together in composite. Seed for the compara- 
tive yield test reported in Table 40 has been obtained each year 
in the same manner. 
(4) Natural crossing of high yielding ear-to-row strains. 
Hybridization of ear-to-row strains was commenced in 1909, 
using as a basis the same four “Class I” strains that have been 
used in the continuous ear-to-row breeding experiments. The 
first year, two rows of each strain were planted in the middle 
of a twelve-row plat of one of the other strains. These two 
rows were detasseled to supply the hybrid seed. In the follow- 
ing year, and thereafter, the seed stock was continued by inter- 
crossing the four hybrid combinations just as described for the 
individual strains the first year. The strains had lost their 
identity after the first few years and future crossing practically 
amounted to using seed from detasseled rows. The four hybrids 
have been mixed each year for the yield test reported in Table 40. 
RESULTS FROM THE VARIOUS METHODS OF EAR-TO-ROW BREEDING WITH 
HOGUE’S YELLOW DENT CORN 
The comparative yields from the various methods of ear-to- 
row breeding with Hogue’s Yellow Dent corn are given in Table 
40 for the seven-year period 1911-1917. All special selections 
are compared directly with each other and with the original 
Hogue’s Yellow Dent corn, which has been continued by merely 
selecting well- developed ears for seed each year. 
Continuous ear-to-row selection for a period of eight to 
fourteen years resulted in an average yield of 0.3 bushels per 
acre less than the original. Continuing a single strain in an 
isolation plat for a period of four to ten years resulted in an 
average yield of 5.9 bushels j)er acre less than the original. 
Mixing four high yielding ear-to-row strains and growing for a 
period of two to eight years in an isolation plat without further 
special selection resulted in an average yield of 1.4 bushels per 
acre greater than the original. Crossing ear-to-row strains for 
a period of two to eight years resulted in a yield of 0.9 bushel 
per acre more than the original. 
