ASSOCIATIONS BETWEEN NUMBER OF KERNEL ROWS, 
PRODUCTIVENESS, AND DELETERIOUS CHARACTERS 
IN CORN 1 
By Curtis H. Kyle, Agronomist , and Hugo F. Stoneberg, Assistant Agronomist, 
O ffice of Cereal Investigations, Bureau of Plant Industry, United States Depart¬ 
ment of Agriculture 
INTRODUCTION 
Two different methods of selecting seed corn have been used for 
many years in the southern part of the United States. Under one 
of them, seed has been selected from plants bearing two or more 
ears; under the other, seed has been selected on the basis of the size 
of the ear. As a result, two classes of varieties, prolific and nonpro- 
lific, are now in common use. In general, the prolific varieties bear 
more than one ear on a plpnt, whereas the nonprolific varieties bear 
only one. The ears in the prolific varieties are smaller, and it would 
seem that the yields of the two might be equal, the differences in size 
and in number of ears offsetting each other. Experiments with 
comparable varieties have shown otherwise. Studies of the ears in 
prolific and nonprolific varieties showed that there were characteristic 
differences between them in the number of rows of kernels on the ear 
and in the size and angularity of the kernels. 
The effect of differences in these characters upon yield has been 
investigated, using groups of ears within both prolific and nonprolific 
varieties and within a number of F x varietal crosses. The relation of 
the number of rows of kernels to smut resistance, to freedom from 
abnormalities, and to general vigor and productiveness also has been 
studied in self-fertilized lines. It is the object of this paper to present 
the data from these experiments and to discuss their application to 
corn improvement. 
EXPERIMENTAL METHODS 
The soil and climatic conditions where the experiments were made 
usually gave yields of 30 to 50 bushels of corn per acre with a good 
local variety. . The different varieties or selections compared required 
practically the same time to mature, which was well within the 
seasonal nmits. 
From 20 to 50 ears were used to represent each variety or selection. 
Seed ears were selected in the studies on number of rows, etc., that 
differed in the character being studied but that were as nearly alike 
in other respects as the material permitted. All of the seed used was 
examined closely, and defective or irregular kernels were eliminated 
before planting. 
Specially constructed hand planters were used with which an exact 
number of kernels could be planted at a given place and covered 
uniformly. The hills were spaced 3 feet apart in the row, center to 
center, by means of a metal spacing cable. The number of plapts 
per acre was adjusted in accordance with soil productiveness by 
regulating the space between the rows. 
1 Received for publication Sept. 17, 1924; issued September, 1925. 
J ournal of Agricultural Research, 
Washington, D. C. 
(83) 
Vol. XXXI, No. 1 
July 1, 1925 
Key No. G-495 
