52 
S. DEPARTMENT OF AGRICULTURE 
Table 11. — Yields of crosses between selfed lines of Delta Prolific corn as per- 
centages of comparable yields of the parent variety, obtained at Burdette, 
Ark., in 1925 and at Knoxville, Tenn., in 1923 
[Experiments at Burdette, Ark., were in cooperation with the Burdette Plantation (Inc.) and the Arkansas 
Agricultural Experiment Station. Data for Knoxville, Tenn., from Richey and Mayer (64, pp. 12, IS)] 
Acre yields of crosses compared with 
those of the parent variety (per 
cent) 
Pedigrees of parent lines J 
i 
T 
<* 
(M 
CO 
1 
V 
CO 
C<1 
i 
k i o o i o/Burdette 
111 
112 
5-l-3-2-l-3J KnoxviUe 
— i— 
k_i o q o o/Burdette 
137 
70 
o-l-2-3-2-2| Knoxvme 
in o i i i a /Burdette... . __ 
127 
134 
120 
121 
108 
137 
10-3-l-l-l-4| Knoxvme 
m o i i o o /Burdette . . - 
133 
129 
127 
120 
118 
117 
10-3-l-l-2-2| Knosvme 
m o i o i -/Burdette. .. 
10-3-l-2-l-D| Knoxvme __ _ _ 
140 
114 
114 
io-3-i-2-2-3j Knoxville - ::::::::::: 
154 
1 The pedigrees shown are for the lines used in the crosses at Knoxville, Tenn.; those for the lines used 
in the crosses at Burdette, Ark., would be the same with further numbers added. 
With a single exception, for which no reason is known, the results 
are in fair agreement and indicate that increased yields ranging 
from 20 to 30 per cent could be obtained by using any one of several 
crosses. These crosses were all at a disadvantage because of the 
poor seed value due to the seed being produced on the weak plants 
of the selfed lines. In fact, none of the single crosses could be 
recommended for practical use because of danger of a poor stand 
should conditions be unfavorable for germination. This disadvan- 
tage is overcome by double crossing. So far the only data avail- 
able on the yields of double crosses involving the selfed lines of 
Delta Prolific come from duplicate plats of a random mixture of 
double crosses included in the comparison at Burdette, Ark., in 1925. 
The two plats of the double crosses yielded 41.6 and 44.5 per cent 
more than the respective adjacent plats of Delta Prolific. Too much 
confidence should not be placed in the exact size of these increases 
obtained in a single experiment. At the same time they are of an 
order that is consistent with expectation based on the more extensive 
comparisons of the component single crosses. 
The results of the Iowa corn-yield test conducted by the Iowa 
Corn and Small-Grain Growers' Association in cooperation with 
the Iowa Agricultural Experiment Station and the Bureau of Plant 
Industry of the United States Department of Agriculture provide 
further interesting evidence on the productiveness of crosses be- 
tween selfed lines of corn. Any farmer in Iowa may enter his corn 
in this test upon payment of a small fee, and farmers outside of 
Iowa have the same privilege, though the fee is somewhat larger. 
The State is divided into four sections from north to south with 
an eastern, central, and western district in each section for the pur- 
poses of this test. Each variety entered is compared carefully for 
productiveness in one or more districts at the option of the farmer 
