July i, 1921 
Relation of Length of Kernel to Yield of Corn 429 
Determinations of yield were made in plots consisting of six to eight 
rows. They were planted in triplicate. The four inside rows only of 
each plot were harvested for yield. The corn was planted thick in 42-inch 
drill rows and thinned to a uniform stand of one stalk every 21 inches. 
No effort was made to control cross pollination between corn of the 
various types, and undoubtedly the usual amount of cross-fertilization 
took place. 
The yields which are given in Table I are for shelled corn well dried 
in a heated room where the temperature varied from 6o° to 8o° F. The 
probable error was determined by using the formula />. <’.—0.8453^ 
— - r =— - f in which n equals the number of replications. 
n-Jn — 1 
Tabus I.— Yields of smoothmedium-, and rough-dented types of commercial white 
corn, 1916 to 1919 1 
Type. 
1916 
1917 
1918 
1919 
Four-year 
average. 
Smooth. 
41. 7 i°- 79 
41. 2 ± .33 
42. 1 ± . 86 
41 . T ± 0 . 50 
43 - 9 ±i. 29 
45-3 ±1.09 
28. 1 ±0. 97 
23. o± .48 
20. 3 ± . 14 
35 - 2±0. 89 
31 - -35 
34. 2 ± .89 
36. 5±o. 78 
34.8± .61 
35 -S± -74 
Medium. 
Rough. 
1 Expressed in bushels per acre of shelled corn. 
It will be noted that the smooth-dented type produced the highest 
4-year average yield, and that the medium-dented type yielded the least. 
The data are not very consistent for the 4-year period. There was prac¬ 
tically no difference in the yields the first season. In 1917 the rough type 
produced about 2 bushels more than the medium and about 4 bushels 
more than the smooth type. This variation appeared to be due entirely 
to peculiar seasonal conditions at the time the corn was beginning to 
pollinate. Drought and hot winds prevailed during the last of July and 
first week in August and greatly damaged corn that flowered during 
that time. Rains occurred frequently after August 7, making condi¬ 
tions very favorable for corn for the remainder of the season. The smooth 
type of corn started pollinating two or three days earlier than the 
other types, and the earliest plants were injured to some extent. Many 
of the ears were poorly pollinated, especially at the butt. The ears of 
the medium and smooth type appeared to have been normally pollinated. 
Since the rough type of corn was slightly the latest of the three types to 
flower, it more nearly escaped the detrimental effect of the drought and 
for that reason produced a larger yield. 
In 1918 hot, dry weather prevailed throughout the fruiting period of 
the corn. Under these conditions the smooth type, because of its earlier 
maturity, had the advantage and produced about 5 bushels more than 
the medium type and about 8 bushels more than the rough type. The 
difference in the yields for that season are, no doubt, significant. 
