SORGHUM SMUTS AND VABIETAL RESISTANCE 
43 
In experiments 1 to 3 (Table 11) 50 seedlings of each lot were 
originally used, while 25 were used in experiment 4. Red Amber 
sorgo, which is moderately susceptible to the covered kernel smut, 
was used as a check. 
An examination of Table 11 shows that very few plants grew to 
maturity. Further, only 3 infected plants were obtained, 2 of Red 
Amber sorgo and 1 of feterita, both in experiment 2. The head 
of feterita was only partially smutted, some normal kernels being 
produced. These were planted in 1917 and typical feterita plants 
were grown to maturity (PL X, fig. 1). There seemed, therefore, 
to be no question as to the identity of the plant originally infected. 
In 1919 another series of experiments involving the removal of 
the plumule sheath was conducted. The results are shown in 
Table 12. 
Table 12. — Effects of mutilation of germinating kernels of sorghums inoculated 
with covered kernel smut at Manhattan, Kans., in 1919 
Variety 
Serial No. 
Seed- 
lings 
Plants 
infected 
Infec- 
tion 
Standard White milo . . -.--_. . 
C.I. 352 
Number 
204 
68 
1 
9 
Number 

4 
1 
4 
Per cent 

Feterita.. .. . 
C.I. 182 
5.8 
Blackhull kafir 
CI. 207 
100.0 
Red Amber sorgo 
S. P.I. 17548 
44.4 
In these experiments, 20 check plants each of milo and feterita, 
25 of Blackhull kafir, and 22 of Red Amber sorgo were grown. No 
infection resulted in milo or feterita, while six (24 per cent) of the 
plants of Blackhull kafir were infected, and one plant (4.5 per cent) 
of the Red Amber sorgo showed infection. 
In the 1919 experiments the germinating seeds, following inocula- 
tion, were planted in sawdust instead of soil. This may have caused 
some injury to the germinating seeds and the spores on account of 
the slightly acid condition. The removal of the plumule sheaths 
from feterita, however, resulted in 5.8 per cent infection, although 
none of the milo plants became smutted. 
It seems evident that the removal of the plumule sheath in feterita 
increases the chances of infection and that perhaps this structure 
may act as a protecting factor against smut infection. 
The question arises in connection with the sorghum kernel-smut 
infection whether the rate of germination is a factor in resistant 
varieties. A preliminary study of the germination of some of the 
sorghums at various temperatures was conducted in the laboratory 
to discover whether milo, feterita, and some of the other smut- 
resistant sorghums germinated more rapidly than those varieties 
which are susceptible to smut. If this were the case, the freedom from 
smut in these varieties might be explained on the basis of escape. 
GERMINATION STUDIES ON VARIOUS SORGHUMS 
In 1922 a set of germination studies was made, using 100 seeds of 
self-pollinated material of each variety. Twenty seeds of each 
variety were placed in separate Petri dishes, which constituted a 
series for that variety. Upon the completion of one series a second 
