86 Journal of Agricultural Research - voi. xxxi, no. i 
Table II. — Relative 'percentage yields of prolific and nonprolific varieties on four 
farms near Thomasville , Ga ., in 1915 
Variety 
Perfect 
hills 
Rela¬ 
tive 
yield 
Ears 
per 
plant 
Length 
of total 
ears per 
bearing 
plant 
(A) 
Average 
diameter 
of ears 
(B) 
Yield 
index 
(AXB 2 ) 
Barren 
plants 
Kernel 
rows 
per ear 
Prolific varieties: 
Garrick- ___ 
495 
Per cent 
146 
1.32 
Inches 
7.9 
Inches 
1.9 
28.5 
Per cent 
4.8 
11.61 
Wannamaker_ 
476 
142 
1.20 
7.9 
1.9 
28.5 
5.5 
12.41 
Weekley__ 
482 
130 
1.25 
7.2 
1.8 
23.3 
6.2 
12.84 
Whaley_ 
408 
126 
1.29 
7.4 
1.8 
24.0 
6.1 
12.64 
Whatley_ 
467 
124 
1.59 
6.3 
1.8 
20.4 
5.1 
13.38 
Round_ 
472 
103 
1.34 
7.3 
1.6 
18.7 
8.9 
11.44 
Littlecob____ 
308 
86 
1.29 
7.8 
1.5 
17.6 
7.1 
10.18 
Total or average.-_ 
3,108 
«124 
1.33 
7.4 
1.8 
23.0 
o 6.2 
12.07 
Nonprolific varieties: 
Loveless_ 
462 
110 
.86 
8.4 
1.9 
30.3 
9.7 
13.62 
Watson____ 
448 
107 
.98 
7.8 
1.9 
28.2 
14.1 
13.60 
Stone___ 
327 
98 
.88 
8.0 
1.9 
28.9 
14.7 
13.96 
Cochran__ 
464 
87 
.91 
7.5 
1.8 
24.3 
16.8 
13.68 
Gwaltney_ 
395 
87 
.90 
7.2 
2.0 
28.8 
14.7 
12.64 
Laguna. _ _ 
390 
69 
.91 
7.3 
2.1 
32.2 
15.5 
14.69 
Total or average ___ 
2,486 
“93 
.91 
7.7 
1.9 
28.8 
«14.1 
13.70 
“Computed directly from basic data. 
The data in column 7 of Table II were obtained by multiplying 
the average length of total ears per bearing plant by the square of 
the average diameter of the ears. This gives an index of the volume 
of ear produced per bearing plant and consequently an index to the 
yield of the bearing plants. On the basis of the yield index the pro¬ 
lific varieties made their higher yield with a production per bearing 
plant that actually was less than that of the nonprolific varieties. 
Assuming that selection aims to produce the largest individual 
plant yields, the breeders of the nonprolific varieties had evidently 
done more effective work than the breeders of the prolific varieties, 
if only the bearing plants are considered. For some reason, however, 
the returns were smaller. This was due to the fact that the non¬ 
prolific varieties had a disproportionate number of plants without 
t rain. Each of the nonprolific varieties had a larger percentage of 
arren plants than any one of the prolific varieties, the average per¬ 
centage of barren plants being 14.1 per cent for the nonprolific 
group and 6.2 per cent for the prolific group. 
COMPARISONS WITHIN VARIETIES 
In general, the ears in the nonprolific varieties in the preceding 
experiments had more kernel rows and more angular, tighter-fitting 
kernels than the ears in the prolific varieties. In order to study the 
relation of such differences to yield, a series of experiments was 
begun in 1914. In all of these experiments, groups of ears were se¬ 
lected that differed in one or more characters of the ears or kernels. 
The relative productiveness of these groups was then determined. 
Many experiments have been conducted on the relation between 
yield and the different characters of seed ears. The results of these 
were summarized by Richey 3 in 1922 as follows: 
3 Richey, F. D. the experimental basis for the present status of corn breeding. Jour. Amer. 
Soc. Agron. 14:4. 1922. 
