592 
Journal of Agricultural Research 
Vol. XXIII, No. 8 
the stand in every comparison and the average yield per plant in every 
one except group 2. In this group there was evidence of resistance, 
which probably accounts for the different response of the plants in this 
group to the inoculation. 
RELATION OF EARLY VIGOR AND YIELD AS INFLUENCED BY SEED 
INFECTION 
STUDIES OF INDIVIDUAL PLANTS 
General observations, growth records, and yield data on the experi¬ 
mental plots planted with apparently disease-free and diseased seed 
impressed the authors with the fact that the recorded differences in stand 
did not accurately represent the actual differences between the various 
plots of com in their early stages of growth. The classification of the 
plants as vigorous, semivigorous, or weak was an attempt to record more 
accurately tie comparative condition of the plots at that time. Although 
this classification may be subject to personal error at times, it has been 
used advantageously in expressing significant differences in early vigor. 
When this classification was first used a number of plants were selected 
for study about whose classification as vigorous, semivigorous, or weak, 
there was no doubt (PI. 1 and 5). The plants were harvested individually 
and the dry-shelled weight of each ear determined. These data are pre¬ 
sented in Table VI, where one may note the strong correlation existing 
between early vigor and yield, both in average production and in absence 
of barren stalks. Occasionally, however, plants classified as vigorous in 
the juvenile stage either may be barren or produce nubbins only; but 
this is the exception rather than the rule. At least one important dis¬ 
ease of com that does not affect early vigor appreciably appears to cause 
a certain amount of barrenness and nubbin production. This phase of 
the com, root and stalk rot problem will be discussed in another paper. 
Table VI .—Relation of early vigor to yield and barrenness in plants of Reid Yellow 
Dent, classified as vigorous, semivigorous, or weak, 35 days after planting, at Blooming¬ 
ton, III., in igi8 
Points considered. 
Vigorous. 
Semi- 
vigorous. 
Weak. 
Total number of plants. 
601 
3*3 
249.4 
6.5 
259 
3-2 
’ I 39 * 9 
32.8 
250 
9.8 
100. 5 
50.0 
Percentage of plants dying.. 
Average yield per plant (in grams). 
Percentage of barren plants. 
Table VII gives data on an experiment conducted with disease-free 
and diseased seed of Funk Ninety-Day com. The plot was divided and 
one-half was planted with each kind of seed. A glance at the percentage 
of vigorous and weak plants grown from relatively disease-free seed as 
compared with the plants grown from diseased seed shows that the per¬ 
centage of vigorous plants drops from 64.3 in the disease-free half to 
29.1 in the diseased half, while the percentage of weak plants rises from 
8.8 to 19.1. Early vigor and average yield of grain per plant, as well 
as absence of barren stalks, are directly correlated. 
