July 1, 1924 
Inheritance in Kota-Hard Federation Grosses 
13 
inheritance of awns in this cross. 
Complete homozygosity for awned or 
awnless strains apparently is due to 
multiple factors. 
Effect of awns on yield. —The 
physiological effect of the awn on yield 
is a point of considerable economic 
importance. Grantham (17) found that 
awned wheats outyielded awnless on 
the average of many varieties. Hayes 
(19) has summarized the important 
papers on this subject, and after a study 
of awnless, tip-awned, and bearded 
strains from Marquis-Preston crosses 
states: 
The awn of wheat is, therefore, an important 
organ, and the present tendency to breed only 
awnless wheat should not be adopted in entirety 
without further experimental studies. 
Most of the physiological studies 
have been with barley, the most recent 
being that of Harlan and Anthony (18) 
who found that the elimination of the 
awns resulted not only in lower yields, 
but in increased tendency toward shat¬ 
tering as well. Perlitius (26) worked 
with wheat as well as barley. He 
made transpiration studies with both 
Schmid (28) had previously shown, 
after careful experiments, that awnless 
varieties have higher gluten content 
than awned. He also stated that— 
the physiological service of the awn supplies a not 
unimportant work for the normal building of the 
fruit. The amount of its importance stands in 
direct relation to the size of the awn. 
In the present study the mean yields 
of F 2 plants of each awn class and their 
probable errors have been obtained 
from two sources. The data are given 
in Table VII. 
The F 2 data, especially those from 
Mandan, N. Dak., show that there is 
a direct relation between the awn 
length and the yield. The data from 
St. Paul are not as consistent as those 
from Mandan, although the difference 
between the extreme and the parent 
classes is greater. The difference be¬ 
tween the awnless and awned classes 
at St. Paul is 15 per cent, or 0.56 ±0.23 
grams. This difference is 2.43 times 
its probable error and represents odds 
of about 9:1. At Mandan the differ¬ 
ence between the same classes is 11 per 
Table VII.— Mean yield and its probable error of five awn classes of F 2 plants of 
Kota-Hard Federation crosses grown at St. Paul, Minn., and Mandan, N . Dak. 
in 1922 
Locality and class 
Number 
of plants 
j 
i 
Yield in 
grams, 
mean and 
probable 
error 
ST. PAUL, MINN. 
Awnless__ _... _ ... _ 
Apically-awnletted_ _ 
Awnletted__ ..._.. -- . . _ _ 
1 45 
! 171 
200 
68 
78 
3. 70±0.17 
3.67± . 11 
4.15± . 12 
3. 85± . 18 
4. 26± . 15 
Short-awned_ _ _ _ 
Awned_ _ ... _ 
Total and average_ . _ . _ 
562 
3. 95± . 06 
MANDAN, N. DAK. 
Awnless_ _ _. . 
63 
389 
387 
148 
156 
3.91± . 15 
4. 11± . 08 
4.13± . 06 
4. 16± . 09 
4. 35± . 10 
Apically-awnletted_ ____ 
Awnletted_ ...... . .. . 
Short-awned_ 
Awned__ 
Total and average_ . ... 
1.143 
4. 06± . 03 
winter and spring wheats, using (1) 
awned, (2) awns removed, and (3) awn¬ 
less lots. He concluded: 
The awns of the spike are important for trans¬ 
piration. This transpiration is nearly half that of 
the total transpiration of the head when awned 
heads of wheat and heads with awns removed are 
compared. 
He also stated: 
The awn has an important influence on the 
volume and weight of the kernel [and] a marked 
effect on kernel quality which exhibited itself 
chiefly in an increase in starch content in awned 
sorts. 
cent or 0.44 ±0.18 grams. This differ¬ 
ence is 2.44 times its probable error, 
also indicating odds of about 9:1. 
While these differences can not be 
definitely said to be significant, the 
awns apparently are of some impor¬ 
tance under droughty as well as humid 
conditions. 
In 1923 nine hundred F 3 plants 
grown at Mandan, N. Dak., were 
threshed and the yields of the five awn 
classes averaged. These data are given 
in Table VIII. 
