May 15, 1925 
Inheritance of Botanical Characters in Barley 
919 
generations were grown in the United 
States Department of Agriculture 
greenhouse at Arlington Experiment 
Farm, Rosslyn, Va., in the winter 
of 1921-22 and also in the plant 
breeding nursery at University Farm 
in 1922. Second generations were 
grown at University Farm in 1922 and 
1923. Progeny from the 1922 F 2 
generation plants were tested for 
breeding behavior in 1923. 
EXPERIMENTAL RESULTS 
In the presentation of the experi¬ 
mental results the data will be consid¬ 
ered only for those characters for which 
the results seemingly warrant rather 
definite conclusions. 
CYTOLOGICAL STUDY 
So far as the writer is aware, no other 
work has been done in America on the 
chromosome numbers in barley species. 
The reports of Nakao and Ufcfisch are 
incomplete, not all cultivated species 
being included. 
The photomicrographs included here 
are from transverse sections of the 
root tips of barley. The killing fluid 
used is a modification of BouhTs (used 
first by Allen ( 1 ) and recently used suc¬ 
cessfully by Sax 4 ) on wheat material 
at the Maine Agricultural Experiment 
Station. The sections were cut 5 u 
thick and stained with Haidenhain’s 
iron alum haematoxvlin. 
Since crosses of varieties of the four 
cultivated species show no sterility and 
the chromosome number of some 
species was shown to be 14 in the 
somatic cells, one naturally would ex¬ 
pect to find the same number in all cul¬ 
tivated species. A variety of each of 
the species Hordeum vulgare, H. inter¬ 
medium, II . distichon, and H. dejiciens 
is included in the cytological study. 
The chromosome number is the same 
for all varieties studied—that is, 14 in 
the somatic cells. This fact leads one 
to conclude that seven linkage groups 
will be found. On the basis of chro¬ 
mosome numbers, all varieties of these 
four species belong in one group (pis. 1 
and 2 ). 
As the writer is interested mainly in 
chromosome number from the stand¬ 
point of linkage groups, and since the 
photomicrographs show the number 
clearly, no drawings were made. One 
peculiarity of structure seems worth 
noting, however (pi. 1 , A and B), and 
that is a more or less definite area near 
the end of a chromosome which does 
not take the stain. That the piece 
beyond the hyaline area is a part of the 
chromosome back of it is indicated by 
the fact that the small piece is always 
at the end and in line with the main 
part of the chromosome. When the 
chromosomes are long and thin (as iu 
pi. 1 , C), usually two chromosomes 
of the group have this disjointed ap¬ 
pearance. 
INHERITANCE OF DIFFERENTIAL CHAR¬ 
ACTER PAIRS 
Fertility of lateral florets.— 
In the cross H. dejiciens steudeliiX 
Manchuria the Fi plants which were 
grown in the greenhouse could not be 
distinguished from the dejiciens parent. 
Under field conditions, however, many 
Fi plants show slight development of 
the glumes and palets in the laterals, 
and in some seasons the Fi may be 
quite accurately distinguished from the 
homozygous deficiens. In the F 2 gen¬ 
eration, grown in 1922, the plants 
could be grouped quite easily into the 
three types, dejiciens, intermediate, and 
6 -rowed, and approximated closelv a 
1:2:1 ratio (Table I). 
Table I .—Classijication oj F 2 plants for 
the characters, dejiciens and vulgare in 
the cross Hordeum dejiciens steudeliiX 
Manchuria ( vulgare); 1922 
Class 
Vul- 
gare 
Inter¬ 
mediate 
De¬ 
ficiens 
Total 
84 
191 
80 
355 observed. 
89 
178 
89 
| 
356 calculated on 1 : 2 : 1 
basis. 
X 2 =2.14. P=0.3476. 
All plants classed as 6 -rowed in F 2 
bred true for this character in F 3 
(Table II). All of the dejiciens plants 
tested bred true, while all of the plants 
classed as intermediate segregated with 
one exception. 
The heterozygotes and deficiens 
could not always be distinguished in 
the F 2 generation which was grown in 
1923, but when these two groups are 
considered together the resuts show a 
good fit for a 3 : 1 ratio of deficiens and 
intermediates to 6 -rowed (see Table 
III). These results show conclusively 
that the characters 6 -rowed and de- 
4 Sax kindly furnished the writer wi th the details of his method of using Bouin’s killing fluid. 
