596 
Journal of Agricultural Research 
Vol. XXIII, No. S 
A glance at Table XI shows that seed selected from diseased mother 
plants produces plants deficient in early vigor and lacking in the ability 
to produce high grain yields. This is especially pronounced when the 
seed is planted in infested soil. 
Seed ears from badly diseased plants usually are lacking in luster, and 
physical examination of the kernels on such ears frequently shows them 
to be more or less starchy ( 21 ). Specific gravity determinations on these 
kernels also reveal a tendency toward decreased density. Table XII 
gives further data regarding the comparative field performance of starchy 
and slightly starchy seed, as compared with the harder, more homy seed. 
The field stands and seed infections were comparable in all cases. Ordi¬ 
narily, however, as Trost and Hoffer (38) have reported, ears with starchy 
kernels are very often infected with one or more of the com rot pathogenes. 
Table XII. —Influence of endosperm composition (physical determination) on early vigor 
and yield. Data show reduced vigor and reduced yield in plats planted with starchy and 
slightly starchy seed as compared with similar plots grown from horny seed at Blooming¬ 
ton, III . 
Year. 
Condition of seed. 
• 
Total 
number 
of plants. 
Reduction 
in vigor¬ 
ous plants. 
Increase 
in weak 
plants. 
Reduction 
in acre 
yield. 
Reduction 
in acre 
yield. 
Per cent. 
Per cent. 
Bushels. 
Per cent. 
1918 
Starchy. 
1,273 
14*3 
2*7 
i 3 *S 
19.7 
1918 
Slightly starchy. 
9 , 243 
7*7 
3 * 0 
9.9 
14 * S 
1919 
Starchy (individual plants). 
170 
14.0 
4. 0 
8.1 
1920 
Slightly starchy. 
926 
21. 7 
1.0 
4.8 
9.0 
RELATION OP EARI,Y VIGOR TO SIZE OP EARS PRODUCED 
As might be expected from the data presented up to this point, early 
vigor and size of ears are strongly correlated. Plants vigorous and 
apparently healthy in their early stages of growth are much more likely 
to produce good-sized and well-matured ears than plants stunted dining 
this same period. This fact is brought out clearly in Table XIII. 
Table XIII. —Relation of early vigor to the size of ears on 1,715 individual corn plants 
» grown at Bloomington, III. in igi8 
Variety and condition of seed. 
Percentage of plants classified in their 
early stages of growth as vigorous, 
semivigorous, and weak which pro¬ 
duced good-sized, well-matured ears. 
Vigorous. 
Semivigor¬ 
ous. 
Weak. 
Reid Yellow Dent.*. 
67-5 
18. 9 
15 -1 
Funk Ninety-Day (relatively disease-free). 
92. 0 
53*4 
0 
Funk Ninety-Day (diseased seed). 
83.6 
54 * I 
2.0 
RELATION OP EARLY VIGOR TO SHRINKAGE OP GRAIN 
It has been found, as East and Hayes (it) and Grantham (14) have 
reported, and as many other investigators have observed, that weak 
plants are from 7 to 10 days later in tasseling and silking than vigorous 
