8 
Journal o f Agricultural Research 
Vol. XXIX, No. 1 
In some cases the ratio of the fully 
awned to the intermediate and awnless 
in this generation was 1:2:1. 
Saunders {27) questioned the idea 
that the first generation between an 
awnless and an awned wheat always 
is awnless and maintained that the 
character of awns in the Fi varies with 
the wheats used. 
Howard and Howard {22) obtained 
single-factor results in some crosses, 
but in others between fully awned and 
absolutely awnless parents, where the 
Fi plants were nearly awnless, they 
were able to separate the F 2 progeny 
into five or six classes. When all 
the awned and awn-tipped classes were 
grouped as awned the ratio of awned 
to awnless was 15:1, indicating the 
presence of two factors. They con¬ 
cluded that for certain crosses two 
factors, B and T, must be present in a 
homozygous dominant condition in 
bearded wheats and that the com¬ 
pletely awnless plants should be repre¬ 
sented by the double recessive factors. 
These researches and later studies by 
others have proved that awnlessness at 
least is only partially dominant. 
In the present study, in which one 
parent was awned and the other awn¬ 
less and the Fj had apical awnlets from 
3 to 20 mm. long, the F 2 plants were 
distributed into five classes, described 
as ( 1 ) awnless, ( 2 ) apically-awnletted, 
(3) awnletted, (4) short-awned, and 
(5) awned. Spikes representing these 
classes are shown in Plate 1 , B. Class 1 , 
awnless, normally is entirely without 
awnlets in the apical part of the spike, 
although a few awnlets 1 to 2 mm. long 
may occur at the apex under abnormal 
conditions. Class 2 , apically-awn¬ 
letted, has awnlets 2 to 20 mm. long 
at the apex of the spike but rarely ex¬ 
tending to the central and basal por¬ 
tions. Class 3, awnletted, has awnlets 
from 3 to 40 mm. long, the shorter 
occurring at the base of the spike and 
the length increasing toward the apex. 
Class 4, short-awned, has short awns 
throughout, varying from 15 to 50 
mm. long but only about half the 
length of the normal awns. In Class 
5, awned, the awns vary from 30 to 
80 mm. in length. These five divisions 
of the material appear, after a careful 
study, to be rather definite. The data 
obtained are summarized in Table V. 
Sixty-eight Fi families were included 
in the study of these characters. 
The inheritance of the awn or its 
absence in the Kota-Hard Federation 
and reciprocal crosses is shown in 
Table V to be very similar. There is 
no important or consistent evidence of 
maternal influence. 
Attempting an interpretation of the 
F 2 results, it is simplest to group as 
awnless, the three classes ( 1 ) awnless, ( 2 ) 
apically-awnletted, and (3) awnletted; 
and as awned, the two classes (4) short- 
awned, and (5) awned. The total re¬ 
sults are then as follows: 
Awnless, 
classes 
1, 2, 3 
Awned, 
classes 
4, 5 
Obtained_ 
Expected on 3:1 ratio_! 
3, 362 
3, 338 
1,089 
1,113 
Deviation_ 
24 
24 
Probable error «_ 
19.5 
a Probable errors for numters of individuals 
given here and elsewhere in this paper were ob¬ 
tained from tables of probable errors of Mendelian 
ratios, prepared in the Department of Plant Breed¬ 
ing, Cornell University, Ithaca, N. Y., from the 
formula 0.6744898 ^jnpq in which n is the total num¬ 
ber of individuals and p and q the numbers corre¬ 
sponding to the ratios concerned. 
The deviation of only 24 ± 19.5 shows 
a very close fit. The presence of one 
principal genetic factor is thus indi¬ 
cated. It is obvious, however, that 
this is not a certain or complete expla¬ 
nation. 
The F 2 material, in general, con¬ 
tained many more awned or awnless 
plants than would be expected on a 
2 -factor hypothesis. Thus the ne¬ 
cessity for growing and examining the 
F 3 progeny to obtain further in¬ 
formation was very apparent. 
A further study on the inheritance 
of the awn was made on F 3 material 
grown at Mandan, N. Dak., and 
Davis, Calif., in 1923. As many as 
434 selections, which were mostly 
rust-resistant red wheats, were grown 
at Mandan. Of these 291 were from 
F 2 material grown there and 143 were 
from the F 2 material grown at St. 
Paul, Minn., in 1922. At Davis, 
there were grown 197 selections which 
were both red and white wheats from 
F 2 material grown there the previous 
year, although they included a few 
white-kerneled, rust-resistant selections 
from St. Paul. The data obtained 
from F 3 material are summarized in 
Table VI. 
