July i, 1921 
Relation of Length of Kernel to Yield of Corn 
437 
Table XIV. Percentage of grain to cob for the progeny of smooth, medium, and rough 
ears, 1916-1919 
Year and type. 
Percentage 
of grain to 
cob. 
Year and type. 
Percentage 
of grain to 
cob. 
1916: 
Smooth. 
77-9 
79-5 
80. 
1919: 
Smooth 
76.9 
Medium. 
Medium 
Rough. 
Ropgh 
79. O 
81.2 
1917: 
Smooth. 
80. 7 
Four-year average: 
Smooth 
Medium. 
81. 4 
Med ium 
70. 2 
Rough. 
82.3 
79 - 7 
81.0 
1918: 
Smooth. 
XXUUgll... 
Medium. 
77 - 5 
Rough. 
70. 9 
80. 0 
PRACTICAL APPLICATION 
Because of the popular opinion that smoothness of ears is an indication 
of deterioration, the results of this study are of practical interest. Smooth 
corn has several advantages over medium or rough. Every corn grower 
knows that the smooth type is much to be preferred at husking time- 
This type is not so subject to damage from molds and other fungi fol¬ 
lowing injury to the ears from the corn earworm. The latter factor is 
often an important one, since moldy corn is dangerous to feed. Rough 
ears, because of the length of kernel and circumference of the ears, do 
not dry out as rapidly as the smooth type, and for this reason they are 
more likely to be low in vitality as a result of freezing. Smooth kernels 
are less likely to rot when conditions for germination are unfavorable. 
It would seem, therefore, that the corn grower should not hesitate to 
select smooth ears. It may be well to select slightly rougher ears than 
are desired in the progeny, since there appears to be a decided tendency 
to vary toward the smooth type. It is also well to do this in order to 
avoid a hard, flinty type of kernel that would be unsatisfactory for feed¬ 
ing without grinding. 
CONCLUSIONS 
The popular opinion that smoothness in corn is an indication of 
deterioration and reduced yielding capacity appears to be erroneous. 
In the experiments reported the smooth type yielded as well as the 
medium and rough types on the average and indicated that under adverse 
conditions it will yield better. 
Continuous selection of smooth and rather short kernels for four gen¬ 
erations increased the average length of the ears, decreased the circum¬ 
ference, slightly decreased the weight, decreased the number of rows 
per ear, and decreased the length of the kernel and the percentage of 
shelled grain. 
On the other hand, continuous selection of rough and rather long 
kernels decreased the average length of the ear and increased the cir¬ 
cumference but had no significant effect on the weight of ears, the num¬ 
ber of rows per ear, the length of the kernel, or the percentage of grain. 
